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• We address a less studied topic: states' cultural response to disasters. • We propose a perspective based on the cultural sociology of the state and cultural theories of trauma, theodicy, and performance. • States' cultural response is " performance ": states project their definitions of situation of disasters and construct their positive self-images when interacting with the publics. • The efficacy of their performance depends on how effectively states' address the key components of the " nomos " or " meaning structure " about catastrophes and suffering and how this performance is influenced by their political structures. • Our theoretical perspective is illustrated in a comparative study of the 2008 Sichuan earthquake in China and the 2005 Hurricane Katrina in the US. • The findings also speak to an enduring debate over whether democratic or authoritarian regimes perform better in disaster responses. The sociology of disaster has paid scant attention to states' cultural response—states' effort to use meaningful narratives and symbolic actions to address issues about citizens' suffering and death to enhance their legitimacy and secure citizens' support. Our paper starts to address this gap by asking: How do states culturally respond to massive disasters? How effective are their responses? What can explain the efficacy of their cultural responses? We propose a perspective based on the cultural sociology of the state and cultural theories of trauma, theodicy, and performance. We illustrate this perspective in a comparative study of the 2008 Sichuan earthquake in China and the 2005 Hurricane Katrina in the United States. We argue that the efficacy of their cultural responses depended on whether and how effectively they addressed the key components of the meaning structure of disasters through compassionate reaction to citizens' suffering and death, convincing accounts of states' accountability, and cogent narratives about the long-term consequences of disasters on citizens. Both states struggled to address these issues at various points in their respective disasters, and their cultural responses were shaped by their political structures. The findings also speak to an enduring debate over whether democratic or authoritarian regimes perform better in disaster responses. We eschew the exclusive focus of the debate on administrative responses and its simplistic correlation between regime type and responses. [ABSTRACT FROM AUTHOR]

This paper develops an improved three-dimensional sphere discontinuous deformation analysis (SDDA) model and uses UAV-based photogrammetry to enable SDDA to numerically analyze potential long-runout debris flows in Zheduotang area along the Sichuan-Tibet railway. First, the original SDDA is improved by proposing a sphere-sphere bonding algorithm to bond spheres with tetrahedral layout to form four-sphere clusters to approximate non-sphere particles in debris flow. Second, the capacity of the improved SDDA is verified by comparing modelling results with four groups of laboratory tests of granular flow. Third, UAV-based photogrammetry is used to obtain the real morphology of the extremely complex terrain surface of Zheduotang area which is finally transferred into a large number of triangular faces as the fixed boundary faces of SDDA. Then, three potential debris flow scenarios on this terrain surface are numerically studied, and some suggestions for engineering disaster prevention are drawn. Model performance shows that, the improved SDDA is a feasible tool to simulate debris flows. With the help of UAV-based photogrammetry, it shows significantly helpful for geohazard prevention for infrastructures in mountainous areas like the Sichuan-Tibet railway. • An improved sphere discontinuous deformation analysis model is proposed. • The validation of the improved model in debris flow simulation is verified. • UAV-based photogrammetry to parameterize the extremely complex terrain surface of mountainous area is used. • Engineering-scale long-runout debris flow simulations are carried out. [ABSTRACT FROM AUTHOR]

Carbon emissions in air travel have attracted widespread attention with the fast development of the aviation sector. Currently, biofuel usage has the potential to curb these emissions due to the bottleneck of other aircraft emission reduction technologies. This paper studies carbon tax policy-induced air travel carbon emission reduction and biofuel usage in China considering the interactive relationship between an authority and multiple airlines by a bi-level model and an interactive solution approach. Then a case study based on airlines from southern China's Sichuan Province is conducted to explore useful insights, with scenario analyses being performed. The computational results indicate that the policy could be useful for air travel carbon emission reduction and biofuel usage improvement in China. These results and analyses provide insights to the authority for the tradeoffs between policy equity and carbon emissions reduction effectiveness, and airlines for profitability. • Carbon tax policy-induced air travel carbon emission reduction in China is studied. • A bi-level model considering interaction of an authority and airlines is developed. • Trade-off between the effectiveness and equity of the carbon tax policy is analyzed. • A case study based on airlines in China is provided to explore useful insights. • The policy plays a vital role in carbon emission reduction and biofuel usage. [ABSTRACT FROM AUTHOR]

• The influence of curing temperatures on the performances of FRCs were studied. • The curing temperatures and curing ages have positive effects on the compressive strength of concrete. • There is an optimum fiber content for the compressive strength of FRCs cured at low temperatures to resist loads. • The added fibers into concrete improves the ductility of concrete due to the fiber bridging effect. • The negative curing temperatures significantly inhibit the hydration reaction. In cold regions or even permafrost areas, it shows growing interests in engineering infrastructures, and more engineering projects have been constructing, e.g. Sichuan-Tibet railway. Undoubtedly, the concrete needs to be cured at the temperature below the conventional curing temperature (about 20 °C). This paper investigated the effect of curing temperatures (i.e. −6 °C, −2 °C, 2 °C and 6 °C) on the performances (compressive strength, stress–strain relationship, microstructure, and hydration products) of steel fiber-reinforced concrete (SFRC), polypropylene fiber-reinforced concrete (PPFRC), and basalt fiber-reinforced concrete (BFRC). The results show that the curing temperature and curing age have positive effects on the compressive strength of concrete samples, and the compressive strength increases with the curing temperatures and curing ages. Besides, regardless of curing temperatures, the type and dosage of added fibers would greatly affect the compressive strength, and there is an optimum fiber content for the compressive strength of FRCs cured at the low temperature to resist loads, and the optimum fiber contents for the SFRC, PPFRC and BFRC are 2.0%, 2.0‰ and 0.5‰, respectively. Additionally, the axial stress–strain curves can be divided into four-section characteristics, i.e. linear ascending stage, plastic yield stage, descending stage and residual stress stage. The addition of fibers into concrete remarkably improves the ductility of concrete due to the fiber bridging effect. Moreover, the negative curing temperatures drastically inhibit the hydration reaction of concrete. Denser microstructure, more hydration products and good fiber–matrix binding quality can be observed in the concrete samples cured at the higher temperatures. [ABSTRACT FROM AUTHOR]

• Distribution and evolution of middle-deep groundwater in marine strata were studied. • Qinling-Dabie and Jiangnan orogenic belt affected the erosion of the strata. • Transfer direction of tectonic stress affects hydrochemical types and flow paths. • Salinity comes from connate water and/or dissolved rock flushed by rainwater. Large marine sedimentary basins often contain concentrated geothermal mineral resources. Chongqing Municipality, located in the Sichuan marine sedimentary basin and the surrounding mountainous area of southwest China, is rich in thermal waters and brines. Chongqing belongs to the Middle-Upper Yangtze Tectonic Block. Previous studies have mostly been based on basin structure, but less on the whole plate structure to study the distribution and evolution of groundwater. In this paper, 78 middle-deep groundwater samples in the study area were collected to better understand the occurrence and hydrochemical evolution of middle-deep groundwater using ionic ratios, hydrogen and oxygen isotopes, and geothermometers. Tectonic stress has been transferred from SE to NW in the Jiangnan Orogenic Belt and from NE to SW in the Qinling-Dabie Orogenic Belt, making the extent of tectonic denudation and its related properties such as hydrochemical type, reservoir temperature, and maximum circulation depth trend along the same directions. Four of the water samples have Br × 103/Cl and Na/Cl molar ratios >1.5 and <0.87, respectively, indicating that they are marine metamorphic brines. The ratios of the rest of the samples are mostly distributed in a range suggesting precipitation-dissolved halite or somewhere in between. This suggests that the study area is in the denudation leaching period of the hydrogeological cycle, and the middle-deep groundwater system is still in the dynamic process of formation water (residual metamorphic paleo-seawater) of the previous hydrogeological cycle diluted in places by rainwater. A conceptual circulation model for regional middle-deep groundwater is proposed. Rainfall in the late Pleistocene infiltrated as groundwater recharge via fractures and karst valleys and circulated to deep strata driven by gravity, where it could mix with residual, paleo-evaporated seawater. Then the groundwater was heated by geothermal and chemical energy sources, mixing with shallow groundwater as it moved upward along faults toward the surface eventually to emerge from springs. [ABSTRACT FROM AUTHOR]

Total organic carbon (TOC) content is significant for "sweet spots" prediction and resource calculation. Traditional physical methods and machine learning methods, however, only use labeled samples (core TOC samples and well logging data) to predict TOC, resulting in a performance bottleneck. Meanwhile, many oilfields have considerable unlabeled data (well logging data). Therefore, this paper proposed a pretrain-and-finetune few-shot learning framework, called Contrastive Learning-Convolutional Neural Network (CL-CNN), to predict TOC using unlabeled data. CL has been a research hotspot in unsupervised learning in recent years, with the principle of reducing the distance between similar samples and increasing the distance between different samples in the feature space. CNN is distinguished by its strong generalization ability and high prediction accuracy, as well as its local connectivity and weight sharing. The CL-CNN model first uses CL to pretrain the initial parameters of the CNN model on a large number of unlabeled datasets and then finetunes the resultant CNN model using the labeled data. The framework combines the advantages of CL and CNN to further improve the prediction accuracy and generalization ability. The proposed method was applied to predict the TOC of shale gas in the Sichuan Basin, China, using 121 core samples and 1224 well logging data from the JY 10 well (121 logging data for supervised learning and 1103 logging data for unsupervised learning). Besides, JY 10–10 well data were used to validate the CL-CNN model. Experimental results demonstrated that the CL-CNN model outperformed many machine learning methods, including the support vector machine (SVM), Gaussian process regression (GPR), random forest (RF), and CNN models, indicating the feasibility and effectiveness of the proposed method. Because of this, the CL-CNN model can also be used as a general prediction tool for reservoir parameters such as porosity and permeability. • Contrastive learning was used to learn the general attributes of the unlabeled data. • Contrastive learning-convolutional neural network (CL-CNN) was proposed to predict TOC content. • Unsupervised pretraining and supervised finetuning were used for few-shot TOC prediction. • CL-CNN obtained promising results for predicting TOC and outperformed many methods. • The plane distribution of TOC in the study area was predicted by CL-CNN accurately. [ABSTRACT FROM AUTHOR]

High-quality reservoirs in the third member of Lower Triassic Feixianguan Formation in the Jiannan area are exclusively restricted to dolostone, which makes it essential to understand origin of porosity in dolostone. However, the studies on the porosity origin of the dolostone in the Jiannan area are rare, and its origin is still controversial. In the paper, the formation mechanisms of porosity in replacement dolostones ever proposed worldwide are summarized, and they can be divided into two main categories based on the formation time of porosity relative to the dolomitization process: syndolomitization and postdolomitization origin. Studies on well cores that have been dolomitized to varying degrees indicate that the porosity in dolostones in the Jiannan area is a syndolomitization origin which is intimately associated with the dolomitization process, depending mainly on the degrees of dolomitization. Four stages of porosity evolution, each with distinctive petrographic and petrophysical properties, were distinguished. In initial stage of dolomitization (stage I), dolomite was formed mainly by volume for volume replacement with porosity constant or slight decrease due to external carbonate source added. In the next stages of progressive dolomitization (stage II), only minor intercrystalline pores were developed and the porosity slightly increased. In more advanced stage (stage III), abundant intercrystalline, as well as some vuggy pores, were formed by selectively dissolution of residual microcrystalline calcites and micritized grains, and the porosity remarkably increased with increasing dolomite content. In the most advanced stage (stage IV), dolomite cements were precipitated in pre-exiting pores in dolostone, resulting in varying decrease in porosity and permeability. Carbonates that must proceed at least in the stage III have the high porosity, while the dolostones in the stage II-2 that display similar rock frameworks only have a minor increase in porosity. [ABSTRACT FROM AUTHOR]

The 20 April 2013 Lushan earthquake with a magnitude of M s 7.0 induced widespread landsliding along the southern segment of the Longmen Shan fault zone. This paper presents a preliminary analysis of the characteristics of these co-seismic landslides triggered in an area of 13,323 km 2 . A total of 3810 individual landslide points were identified through an intensive field investigation and from digital aerial photographs taken after the Lushan earthquake. To facilitate the more detailed analysis on the areal frequency of co-seismic landslides as polygons, we selected an area of 732 km 2 around the epicenter that had the highest density of co-seismic landslides. The sizes of the landslides are, in general, much smaller than those that were triggered by the 2008 Wenchuan earthquake. The most common types of landslides in the study area were rock falls and shallow, disrupted landslides from steep slopes, which typically involved the top few meters of weathered bedrock and colluvium. In this study, the relation between the landslide distribution and five main factors was analyzed: fault proximity, epicenter proximity, peak ground acceleration (PGA), slope angle, and lithology. Our study results show that the landslide concentration tends to decrease with distance from the seismogenic fault, and the highest landslide concentration is located within a distance of 5 km. Regarding the distance to the epicenter, the largest landslide density is found at a distance between 5 and 10 km. The landslide concentration also increases with increasing slope angle until a maximum for the slope class 45°–55°. In addition, results show that slopes consisting of deeply weathered and fractured sandstones and mudstones were the most susceptible to co-seismic landslides. In this study, we found that the location of the hanging wall and the footwall of the fault did not seem to have an important effect on the landslide distribution. This is in contradiction to what has been reported in other earthquake areas such as the Wenchuan area. [ABSTRACT FROM AUTHOR]

Chengdu, located at the western edge of the Sichuan Basin, is the provincial capital of Sichuan Province. The fertile and well-watered basin has given the city a long and splendid history, which has left significant and lasting imprints on its urban form, landscape and cultural life. In the planned economy period, Chengdu serviced as the economic, cultural, logistical and technological center for southwest China, and built a competitive and broad industrial base which now helps the city maintain its leading position in the region. In 2007, Chengdu was assigned as one of two pioneer cities in coordinating urban–rural development. This paper introduces the urban development of Chengdu as a historical city, summarizes the city’s economic growth, urban spatial transformation and infrastructure construction as a major city in western China, and discusses its recent efforts in coordinating urban–rural development as a pioneering city in China. [ABSTRACT FROM AUTHOR]

On April 20, 2013, an earthquake of M7.0 occurred in Lushan, Sichuan province, China. This paper investigates the coseismic ionospheric anomalies using GPS (Global Positioning System) data from 23 reference stations in Sichuan province that are a part of the Crustal Movement Observation Network of China (CMONOC). The recorded results show that a clear ionospheric anomaly occurred within 15 min after the earthquake near the epicenter, and the occurrence time of the anomalies recorded by various stations is related to the distance from the epicenter. The maximum anomaly is 0.25 TECu, with a 2 min duration and the distance of the recording station to the epicenter is 83 km. Acoustic waves generated by the crustal vertical movement during the earthquake propagate up to the height of the ionosphere lead to the ionospheric anomaly, and the propagation speed of the acoustic wave is calculated as 0.72 ± 0.04 km/s based on the propagation time and propagation distance, consistent with the average speed of sound waves within a 0–450 km atmospheric height. [ABSTRACT FROM AUTHOR]

• Analysis of the techno-economic pathways to net-zero emission attainment in China. • Analysis of peak carbon emission and carbon neutrality by year 2030 and 2050. • Solar PV, biomass, hydro, and wind power are considered for 100 % decarbonization. • River hydro is constructed considering dry, normal, and wet years. • Carbon emission is reduced by 13.26% to 15.3% between 2030 and 2050. With the imminent acute problems and the harsh reality of climate change, many countries/groups of countries have developed policies to reduce their carbon emission. At the end of 2020, the Chinese government announced a revised policy that will see the country attain carbon neutrality by 2060 and peak emission by 2030. This study aims to determine the techno-economic requirements for net-zero emission attainment in China. The models created are used to explicate the 100% integration of renewable energy into the energy systems in a Province in China considering the years 2030 and 2050. This study is novel as it aggregates the detailed requirements of all the energy sectors and the government policies for the case study. While the approach presented in this paper is applied specifically to Sichuan Province, China, the application of this method is limitless as it is vast and viable for other countries. This study can also serve as a template for many high carbon-emitting countries with sizeable RE potential. The total energy demand in the case study is summarized under three sectors; electricity, industry, and transport. Following the government policies, renewable energy sources such as wind power, solar PV, river hydro, and biomass are considered for 100% decarbonization of the case study. River hydro being the predominant renewable energy source in this region is constructed considering three levels of hydro (dry, normal, and wet) years. The 2017 energy demand and supply data are first used to develop/validate the model on the EnergyPLAN simulation platform, then the 2030 proposed pathway to peak carbon emission by the government is analyzed. Three innovative pathways to net-zero emission attainment by 2050 are proposed in this study considering the additional use of biomass (BIO model), pumped hydro storage (EES model), and the import of clean electricity from neighboring provinces (IMP model). Based on the analyses in this study, the proposed pathway by the government cannot achieve net-zero emission by 2050, however, the three optimized strategies/models presented in this study show a clearer and faster path to decarbonization. Carbon emission will reduce by 13.26 %, 14.77%, and 15.3 % between 2030 and 2050 reference models for the dry, normal, and wet year scenarios respectively. From the three optimization models, the total cost of the import model was the lowest under different scenarios. Therefore, the economic feasibility of this approach proves the superiority of the import model in terms of economic benefits. [ABSTRACT FROM AUTHOR]

The volcanic rock with developed pores is important reservoir for oil and gas, but its complex pore-fracture structural characteristics lead to the hydration reaction when the volcanic strata is invaded by drilling fluid or fracturing fluid, which brings great challenges to the drilling operation and oil and gas production in volcanic rock reservoir. In order to understand the influence of clay hydration on the pore characteristics and permeability of different types of volcanic reservoirs. In this paper, we selected distilled water as the imbibition solution, and obtained the variation law of pore structure and physical properties of Permian tuff and basalt in Sichuan Basin during pressurized imbibition through a series of indoor test methods. The results show that the clay content of tuff is high, and the clay hydration produces new cracks during soaking, which leads to the increase of nuclear magnetic porosity of tuff after soaking. At the same time, it also makes some unconnected pores connected with each other, resulting in the increase of rock permeability in the later stage of soaking. During soaking, mineral particles peel off, and some clay minerals are transported to pores and fractures under hydrodynamic action, resulting in the reduction of effective porosity of tuff. The basalt is dense with poor physical properties. There are almost no cracks in the rock soaked for 0–24 h. After soaking for 48 h, new cracks are generated in the rock, which may be caused by the increase of pore pressure in the rock. The mineral particles around the crack obviously fall off and block the pore throat, resulting in the reduction of rock permeability after soaking. This study provides not only helps for avoiding the occurrence of lost circulation, well collapse and other accidents, efficient and safe drilling, but also a theoretical basis for the development of hydraulic fracturing in volcanic reservoirs. • The pore structure and physical properties of volcanic rocks with different soaking time were studied. • The influence of complex pore structure and rock type on the hydration of volcanic rocks is considered. • According to the experimental analysis, the hydration of volcanic rocks is divided into three stages. • The hydration of volcanic rock will produce cracks, accompanied by the spalling of minerals. [ABSTRACT FROM AUTHOR]

Pores and throats are the key parameters for determining the pore structure and fluid flow behavior in tight sandstone reservoirs. In this paper, pores and throats of the tight sandstone reservoir of the Upper Triassic Xujiahe Formation in the northern Sichuan Basin were investigated using classical petrography, scanning electron microscopy, and confocal laser scanning microscopy. In addition, a method of pore as well as throat identification and quantitatification using high-pressure mercury injection (HPMI) measurements was worked out. The results show that clay mineral-related pores are well developed in lithic sandstone and feldspathic lithic sandstone in addition to pores produced by dissolution of calcite cement and clastic grains. Intergranular pores are connected by lamellar, curved lamellar, and narrow pore throats. The pores and throats associated with intragranular dissolution and clay minerals are mostly tube shaped. The rapid-increasing and slow-increasing profiles of the mercury injection curves represent the dominance of pores and throats, respectively, allowing to differentiate pores and throats. Calculations show, in addition to fractured lithic sandstone, that has micron-sized pore–throat systems, the other lithic sandstones possess dominatly nano-sized pore–throat systems. In case of feldspathic lithic sandstones, micron-sized and nano-sized pore throat systems are equally important. In micron-sized pore throat dominated reservoirs, the pore volume is slightly larger than the throat volume, whereas for the nano-sized pore throat system, the pore volume is considerably larger than the throat volume. The key factors that are favorable for the formation of lithic sandstone pore throat systems are early calcite dissolution, lithic fragments dissolution, and early chlorite cementation. In contrast the key factors that are favorable for the formation of feldspathic lithic sandstone pore throat systems are dissolution of feldspars and lithic fragments. • A new method to distinguish pores and throats within tight sandstone reservoirs is proposed. • Lithic and feldspathic lithic sandstone reservoirs host different pore and throat types. • Pore volume is slightly larger than throat volume in the micron-size pore network. • Pore volume is considerably larger than throat volume in the nano-size pore network. • Compaction, cementation, and dissolution directly affected the development of pore throat systems. [ABSTRACT FROM AUTHOR]

With the development of exploration and exploitation technologies, deep shale gas systems are gradually becoming an important target for the future petroleum industry. However, there is still a lack of systematic geological studies for deep shale gas systems, which restricts further exploration. In this paper, the deeply buried shales (more than 4000 m in depth) of the first member of Silurian Longmaxi (S 1 l1) at the southeastern margin of the Sichuan Basin are selected as the research object, and thin sections, scanning electron microscope (SEM) observations, total organic carbon (TOC) testing, nitrogen adsorption (NA), and major and trace element analyses are used to systemically identify the different lithofacies and delineate geological and geochemical features. Moreover, we reconstruct the paleoenvironment, summarize the controlling factors and mechanisms of organic matter accumulation and pore formation, and finally reveal the favorable exploration lithofacies. Our results show that there are four lithofacies that can be identified in deep S 1 l1 shale, namely, laminated organic-rich siliceous shale (S), laminated organic-rich mixed shale (RM), banded organic-lean mixed shale (LM), and banded organic-lean argillaceous shale (CM). Organic matter-hosted pores are the primary type in their pore system. The S and RM shales were mainly deposited under dysoxic to anoxic conditions with moderate watermass restriction, low terrestrial detrital influx, and high paleoproductivity, and the silica mainly originated from the diagenesis process (biogenic quartz); the LM and CM shales were sedimented under oxic conditions with high terrestrial detrital influx and low paleoproductivity, and the silica mainly originated from terrestrial detrital influx. Redox conditions, paleoproductivity, and terrestrial detrital influx together controlled the organic matter enrichment in the deep S 1 l1 shale, and the TOC content further influences the physical properties of the shale, thus determining the exploration potential of different lithofacies. Moreover, the significant impacts of lithofacies on the geological and geochemical features of the deep shale gas system are demonstrated. Compared with the middle-shallow shale gas system in the study area, due to less tectonically uplifted and tectonically active shale, the deep shale has more extraordinary preservation conditions, overpressure inheritance development, and higher gas amounts. The S and RM in S l l1 in the study area have better resource potential and should be given more attention in the future. • Geological and geochemical features of different lithofacies in deep shale gas systems are systematically characterized. • Paleoenvironment, organic matter accumulation, and pore formation mechanisms of different lithofacies are revealed. • Lithofacies has a considerable influence on the deep shale gas system, which is consistent with the system in shallow-middle depths. • Compared with shallow-middle shale gas systems, deep shale gas accumulations are generally characterized by overpressure, which leads to a high gas amount. • Overpressure may be due to variations in tectonic activity and preservation conditions. [ABSTRACT FROM AUTHOR]

Opening windows is an important factor when creating a comfortable indoor environment. However, research on window opening behavior in the Chinese region of hot summers and cold winters is limited. In addition, almost all previous research in this area has focused on the average characteristics of the sample mostly by building models of averageness, which largely erases individual behavioral attributes. To fill the gap, an empirical measurement and modeling study of window opening behavior was conducted in seven households in Zigong, Sichuan Province. The following was found: (1) The window opening behavior of residents in different cities in hot summer and cold winter regions significantly differed. The average daily duration of window opening by the test subjects in this paper is 1122 min/day, which is 2–5.5 times higher than previously published literature on this climate zone suggests. (2) Among the test subjects, three typical window opening behaviors were noticed based on the average daily window-opening probability (R), i.e., positive (R>95%), negative (R ≤ 5%), and high-intensity window opening (65% < R ≤ 95%). The first two categories refer to personal habits of residents independent of environmental and temporal factors. (3) High-intensity window opening behavior provided imbalanced data which is more accurately modeled by the random forest model (98.9% prediction accuracy) than the binary logistic regression and decision tree models, i.e., 14.5% more accurate than the former and 12.5% more accurate than the latter. Moreover, it was found that the relative humidity indoors is the factor that contributed the most to the accuracy of the model. • Significant differences in occupants' window-opening behaviors in the same climate zone. • Data samples regarding window-opening behavior should be individually analyzed. • Three types of behavior were identified based on "average daily window-opening probability". • Random forest algorithm had better prediction compared to logistic regression and decision tree. [ABSTRACT FROM AUTHOR]

A new sauropod-dominanted dinosaur fauna, including several new species of sauropods and stegosaurs, was recently excavated from the Lower Shaximiao Formation in Yunyang, northeastern Chongqing, southwestern China. Although this dinosaur fauna could possibly provide significant clues for a better understanding of the basal sauropod's evolution and diversification of basal sauropods in the Jurassic, many aspects of this fauna are not well defined constrained in terms of detailed stratigraphy, geochronology, and comparison with similar faunas in other regions of the Sichuan Basin. This paper reports on the petrological features of this locality, using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry (EDS), with laser ablation-multi-collector-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U-Pb geochronology for a tuffaceous siltstone layer beneath the dinosaur fossil-bearing layers from the fossil site. The SEM and XRD results show a typical tuffaceous mineral composition of this layer. Zircon U-Pb data yielded a weighted average age of 166.0 ± 1.5 Ma, indicating a maximum burial age for this dinosaur fauna. This fauna is chronologically comparable with the Shunosaurus-Omeisaurus Fauna, which is primarily found in the central Sichuan Basin. • 166.0 ± 1.5 Ma as the maximum burial age for dinosaur fauna in Chongqing, SW China. • Precise age constraints on newly discovered dinosaur in Lower Shaximiao Formation. • Basal sauropods in Sichuan Basin are younger than biostratigraphic ages. • Providing age constraints on the radiation of basal sauropods in Jurassic. [ABSTRACT FROM AUTHOR]

An appropriate shut-in after fracturing can dramatically enhance performance of wells in shale gas reservoirs. In this study, a novel wettability index and mineral content curve based shut-in time optimization approach was proposed. First, a new experimental device for spontaneous imbibition of fracturing fluid under the conditions of formation temperature and confining pressure was designed. Then, we conduct a set of experiments on shale samples from the Longmaxi Formation (LF) in the Sichuan Basin to measure the water-wet index and determine the critical value of clay content. Finally, the low-field nuclear magnetic resonance (NMR) equipment was used to monitor the water flow in shale micro-pores, based on this, the shut-in time for different shale reservoirs was optimized. The experimental results show that LF shale hydration can induce new micro-fractures, and the fractures shape is mainly shale bedding fractures, with obvious directionality. The clay content is the key factor affecting water wettability of shale and the critical clay content value of type I and type II shale reservoirs was about 39.5%. The optimal shut-in time of type I and type II shale reservoirs are about 20 days and 15 days respectively. Field application of three wells showed that the average daily gas production was increased by 2–3 times. The research results can guide the development of shale gas reservoirs effectively. • In this paper, the water imbibition experiment of shale under the condition of formation temperature and pressure of shale reservoir was carried out, and the critical clay content affecting the imbibition capacity of shale was determined. • On this basis, the shut-in-time of different reservoirs types was further optimized. • The research results play an important guiding role in understanding the flow law of fracturing fluid in shale reservoirs. [ABSTRACT FROM AUTHOR]

Earthquake relic is a unique geoheritage. At present, the research on earthquake relic geoparks or national parks is less domestic and overseas, while the protection, development and exploration are in its infancy. This paper, taking ‘Qingchuan Earthquake Relic Geopark’ (QERG) as an example, analyses the characteristics of the geopark, and explores the development model, in order to provide reference for the earthquake relic geopark and national park development domestic and overseas. [ABSTRACT FROM AUTHOR]

Syntectonic sediments record the growth process of active fold and fault belts. The Quaternary in the Chengdu plain are the syntectonic sediments formed during the structure deformation of the Longmen Shan in Late Cenozoic, which is of great significance for understanding the formation and evolution of the Longmen Shan. However, the geometry and formation of the Quaternary in the Chengdu plain are still unsettled. This paper determines the Quaternary thickness in the Chengdu plain with audio magnetotellurics (AMT), electrical resistivity tomography (ERT) and borehole, and discusses the formation of Quaternary in the Chengdu plain in combination with previous deep and surface data. It also predicts the Quaternary geometry in Chengdu plain by AMT, and concludes that the thickness in Huayuan may be larger than that in Zhuwapu (541 m). The borehole reveals that the Quaternary thickness in the Huayuan is upto 571.3 m, which is the thickest Quaternary so far. With the Longmen Shan piedmont wedging into the Sichuan basin, and under the intense erosion of Minjiang river, structure wedges of different scales are formed and result in salient and recess, which corresponds to the geometry of the Quaternary in the Chengdu plain. Therefore, the coupling between deep structures and surface processes controls the formation of the Quaternary in the Chengdu plain. • The largest thickness of Quaternary in Chengdu Plain is upto 571.3 m revealed by AMT and borehole. • Longmen Shan structure wedges and Minjiang river jointly control the formation of Quaternary strata in Chengdu plain. [ABSTRACT FROM AUTHOR]

Spontaneous imbibition phenomenon caused by capillarity plays an important role in the production of tight sandstone gas. Understanding the effects of bedding direction on liquid imbibition is important as it can give insights into water block phenomena that can negatively impact gas production. In this paper, four tight sandstone specimens were cored from Sichuan Basin, China with different bedding directions (i.e., the angles between the bedding plane and the horizontal plane of four specimens are 0°, 45°, 60° and 90°, respectively). Nuclear magnetic resonance (NMR) technique was used to monitor the fluid distribution changes during the spontaneous imbibition processes of these specimens. The results show that such tight sandstone exhibited strong hydrophilicity with the small pores dominating throughout the imbibition process. The T 2 spectra for all four rocks specimens not only increased upward but also shifted to larger relaxation times due to brine intake along the minerals surface (further indicating the hydrophilic characteristics of this rock). For such tight sandstone, capillary force and friction resistance between the fluid (brine) and mineral surfaces controlled the imbibition processes. For the 0°, 45° and 60° specimens, "stop illusion" phenomena which the imbibed brine volume had a tiny increase during a long period occurred. However, this was not observed in the 90° specimen (where the bedding direction and fluid flow direction are parallel). This is largely attributed to the significant tortuosity in the flow for the 0°, 45° and 60° specimens compared to the 90° specimen, leading the smallest friction resistance existed in the 90° specimen. Among these four specimens, the 0° specimen had the slowest imbibition rate and lowest imbibition efficiency, while the 90° specimen exhibited the fastest rate and highest efficiency. With the aim of maximizing gas production, this work provides some guidance for the selection of directional fracturing and injection-production methods in the exploitation and production of tight sandstone gas field. [Display omitted] • Rock specimens with different bedding directions were used to conduct the spontaneous imbibition experiments monitored by NMR. • Different imbibition behaviors of four specimens were compared and analyzed. • Driving and resistance forces on the fluid during the experiment were summarized and compared. • The "stop illusion" phenomenon was observed and analyzed. [ABSTRACT FROM AUTHOR]

The Longmaxi Formation has abundant shale gas resources. High-yield wells have been obtained in medium-shallow and deep areas in the Sichuan Basin. Quantitative research on the brittle-ductile change in rocks is a basic geological component for caprock evaluation, and it can also be applied to shale gas exploration. This paper fully considers the difference between the lower shale (N1) and upper shale (N2) of the Longmaxi gas-bearing shale. Through total organic carbon (TOC), mineral components, field emission scanning electron microscopy (FE-SEM), and triaxial mechanics experiments, the two groups of shale samples, N1 and N2, were compared and analyzed, and the brittle-ductile transition was quantitatively studied. Based on previous work, a method for the fast calculation of the key over consolidation ratio (OCR) was proposed. The results show that N1 is mainly organic-rich siliceous shale, N2 is primarily organic-poor clay shale and mixed shale, and N1 is generally more brittle than N2. The key OCRs of N1 and N2 are 2.16 and 2.60, respectively. The key confining pressures at which N1 and N2 become fully ductile are 87.87 MPa and 70.28 MPa, respectively. Therefore, the key depths of the brittle zones of N1 and N2 (H b1 and H b2) and the key depths of the ductile zones of N1 and N2 (H d1 and H d2) are obtained. On this basis, a comprehensive model for the Longmaxi shale gas' brittle-ductile transition exploration zone in the Sichuan Basin and H b1 and H b2 maps of the Longmaxi gas-bearing shale have been established. Through comprehensive vertical and horizontal analysis, Longmaxi shale gas exploration risks in different blocks of the Sichuan Basin have been clarified. Therefore, this study of the variation in the brittle-ductile transition has an important guiding role in refining the exploration of Longmaxi shale gas in the Sichuan Basin. • There are obvious differences between the lower shale and the upper shale. • Difference of brittle-ductile transition makes shale gas exploration more complicated. • The new method can quickly calculate the threshold value of over consolidation ratio. • The new model provides more comprehensive guidance for shale gas exploration. [ABSTRACT FROM AUTHOR]

The African swine fever (ASF) has triggered considerable shocks to the pig farming industry, which has become a significant animal disease epidemic. The study explores the effect of epidemic experience on post-outbreak production recovery from resilience and risk perception based on 340 micro-survey data from Sichuan, Henan, and Shandong provinces. Epidemic experience has been shown to impact the degree of post-outbreak production recovery positively, and farmers who have endured epidemics are more likely to recover their production after outbreaks. The mechanistic study indicates that past epidemics in African swine fever shocks can effectively improve farmers' cognitive resilience and management capability, enhance recovery, and reduce risk perception in the aftermath of production recovery. In order to alleviate the endogenous problems caused by selection bias, missing variables, and two-way causality. This paper uses factor analysis to comprehensively measure production recovery capacity and production risk perception, and uses propensity score matching(PSM), instrumental variable method and replacement measurement methods to conduct robustness tests, and find the conclusions are still robust. The empirical analysis shows that the experience of the epidemic will promote the recovery of farmers after the outbreak; the experience of the epidemic will significantly impact the recovery of production after the outbreak for both free-range and professional farmers. [ABSTRACT FROM AUTHOR]

This paper focuses on celestite-carbonate-cemented veins that developed in the Jialingjiang Formation of the Lower Triassic carbonates from the Libixia anticline in eastern Sichuan Basin, China. Comparative petrography and geochemistry of the host rock and vein minerals provide clues to the nature, origin, and evolution of the vein-cementing fluids. The host rocks are composed mainly of micrite dolomite which yields δ18O, δ13C and 87Sr/86Sr ratios close to the values that characterize contemporaneous seawater. Two generations of vein-mineralization were recognized based on textural relationships, fluid inclusion data and isotope geochemistry. The early generation is dominated by celestite and saddle dolomite, formed from hypersaline, Sr-enriched, hydrothermal fluids. The later generation is represented by calcites, precipitated from less saline fluids at lower temperatures. The 87Sr/86Sr ratios of vein dolomite and celestite vary from 0.7076 to 0.7081, significantly lower than those of host carbonate counterparts (0.7078 to 0.7081; average 0.7080). This isotopic discrepancy suggests that the majority of Sr was sourced from deeper sequences of the lower Triassic carbonates, probably associated with thermochemical sulfate reduction for Sr accumulation. It is argued that the fracture systems associated with the Huayingshan fault provided the heat source and served as conduits for migration of hydrothermal fluids through several hundred meters, and the final mineralization occurred as a result of mixture of Sr-enriched brines with sulfate-bearing solutions. The large celestite ore bodies in the studied area are proposed to form related partially to these hydrothermal fluids. [ABSTRACT FROM AUTHOR]

The estimated ultimate recovery (EUR) of a single shale gas well is one of the important evaluation indicators for the scale and benefit development of shale gas. Nevertheless, due to the lack of engineering and geologic data, as well as the limitations of the existing empirical methods, the current production forecasting methods cannot make reasonable predictions for EUR. Therefore, Duong method is used as the prototype in this paper, a rapid and accurate empirical model for improved production prediction is proposed based on the historical production profile analysis of mass producing wells in Sichuan Basin. The accuracy and universality of the new model are verified by production examples in the Weiyuan, Changning, Luzhou and Yuxi blocks of the Sichuan Basin. The examples illustrate that the new model can be applied well in typical wells, and has no limitation of flow regimes for the production prediction of gas wells. In order to solve the problem of production data fluctuation and decline curve deviation caused by stimulation measures in the production process, a multi-segment production prediction model analysis method is proposed based on the improved model in this study and has been well applied in the field. Most importantly, the new model has clear physical parameters and is easy to operate. Performance of the new model based on production data is as reasonable as the modern production decline methods (including analytical model), which is better than existing empirical methods. • Proposing an improved empirical model, which is rapid and accurate. • Less parameters were selected, the new model still has clear physical meaning. • Application condition of the new model is not limited by the flow regime. • Performance of the new model based on production data is as reasonable as the analytical model. • Multi-segment production prediction model is well applied to gas wells with production data fluctuation. [ABSTRACT FROM AUTHOR]

The ultra-deep dolomite reservoir of the Permian Qixia Formation in northwest Sichuan is important for hydrocarbon reservoirs, but the mechanism of dolomite genesis is complex and has long been controversial, thus requiring further elucidation. By studying the dolomite with different types in the Permian Qixia Formation, northwest Sichuan Basin, this paper, based on outcrop sections observation and core description, seeks to find out the dolomitizing fluids' source and the dolomite's genetic mechanism by analyzing the dolomite's rock-mineral and geochemical characteristics. Various technologies are applied, including rock thin section observation, cathode luminescence, carbon and oxygen isotope analyses, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), and inclusion homogenization temperature and salinity. Results show that the dolomite is mainly classified into silty-fine dolomite (Md1), fine-medium dolomite (Md2), medium-coarse dolomite (Md3), and saddle dolomite (SD) filled in the pores. Md1 is formed in the early shallow-burial stage; the dolomitizing fluids are mainly derived from the early seawater sealed in carbonate sediments; and the penesaline seawater is formed by the seepage reflux under a moderate evaporitic environment. Md2 and Md3 are formed in the middle and late shallow-burial stages. Of these two types, Md2 is formed earlier, and the dolomitizing fluids are primarily derived from the seawater sealed in the early stage and partially derived from the residual evaporated seawater and hydrothermal fluids. In contrast, Md3 is formed later, and the dolomitizing fluids are the mixture of the seawater sealed in the early stage and the hydrothermal fluids formed in the late stage. In addition, Md3 was affected by the hydrothermal process more significantly during the formation. SD is deposited and formed when the saturated hydrotherm upwells along with the fracture system in the late stage. This study provides a significant reference for understanding the source and action mechanism of multi-stage dolomitizing fluids and expands the exploration field of the deep dolomite reservoir. • The precise microanalysis is conducted on the dolomite of different grain sizes by the LA-ICP-MS technology. • The geochemical characteristics of dolomites show the trend of continuous and progressive. • Dolomite fluids come from the normal seawater, penesaline seawater. and hydrothermal fluids. [ABSTRACT FROM AUTHOR]

The upper Permian Longtan Formation (LTF) shale is a new shale gas exploration and development focus in China, which was formed in a transitional depositional environment. Because of the difference in the sedimentary environment between marine-continental transitional shale and marine shale, the enrichment characteristics and mechanism of organic matter (OM) are very different. Because of a weak research foundation, the enrichment mechanism of OM in the LTF shale in the Sichuan Basin is still unclear. In this paper, shale samples of the upper Permian LTF from the Well F5 were collected, and the abundance, source and sedimentary environment of organic matter were studied by using paleoclimate, detrital input, redox, paleoproductivity and sedimentation rate parameters. The results show that the TOC content of the LTF shale is high (average = 3.04%) and reaches the high to overmature stage (average = 2.46%), indicating a favorable source rock. The LTF shale was deposited in a humid and hot climate, which was conducive to the growth and prosperity of a large number of plants. The source of organic matter was mainly terrestrial plant fragments. The sedimentary environment of the LTF shale was oxic, it had a high sedimentation rate, which reduced the oxidation rate of OM, promoted the rapid deposition of OM, and ensured the preservation of organic matter. In summary, the enrichment of OM of LTF shale in the Sichuan Basin was affected by the sedimentary environment, which was complicated. The main controlling factors were detrital input, redox conditions and sedimentation rate. • The geochemical characteristics of Permian Longtan Formation (PLTF) shale in eastern Sichuan are analyzed. • The sedimentary paleoenvironment of PLTF shale in eastern Sichuan is reconstructed. • The main controlling factors of organic matter enrichment of PLTF in eastern Sichuan are studied for the first time. [ABSTRACT FROM AUTHOR]

The energy crisis is a major challenge to sustainable development. Governments therefore constantly seek ways to improve energy conservation. In this paper, our goal was to promote energy conservation and simultaneously increase employment. First, based on China's current regional energy conservation model, social energy costs and employment factors are comprehensively considered to construct an inter-provincial cooperative energy conservation model, the minimal core method is used to construct a cooperative interprovincial benefit-distribution model. Second, representative regions of China (Beijing, Shanghai, Shanxi, and Sichuan) were selected to demonstrate the model in an empirical analysis of cooperative provincial energy conservation. It was found that the total employment in Beijing, Shanghai, Shanxi, and Sichuan can be increased by 9.84 × 106 persons, and the total social energy cost can be decreased by US$59.22 × 106. The cooperative benefit distribution model can increase the total benefit by US$65.28 × 106. Finally, to verify the robustness and feasibility of the model, the sensitivity of the model to these changes is analyzed by changing the parameter values, and it was found that the model was both robust and feasible. The research results provide a new way to improve China's current energy conservation model. • The inter-provincial cooperation model for employment and social energy costs (i.e. bi-objective model). • Constructs a social energy cost function. • Considers energy structure factors. • Uses the minimal core method for benefit distribution. [ABSTRACT FROM AUTHOR]

Thermal regime and thermal history are of significant important in basin dynamics and hydrocarbon generation of source rocks. The sedimentary basins in three typical cratons of China, North China Craton (NCC), Yangtze Craton (YC) and Tarim Craton (TC), underwent completely different tectonic background and dynamic mechanism, which resulted in the differentials of their thermal regimes. In this paper, the thermal regimes of the Bohai Bay Basin in the eastern NCC, Tarim Basin in TC, and Sichuan basin in the Upper YC were studied. There has some lower thermal background in the area of western China than eastern side of the NCC. The mean heat flow value of Tarim basin is 42.5 mW/m2, 53.8 mW/m2 in the Sichuan basin and 66.7 mW/m2 in the eastern NCC. And the temperature at 10000 m ultra-depth in the Tarim Basin also shows lower values than that of Sichuan and Bohai Bay basins. The thermal history, modeled from thermal indicators of vitrinite reflectance (R o), equivalent vitrinite reflectance data (R equ), fission track and (U Th)/He data of apatite and zircon, evolved differently because of the different tectonic history in these basins. The Tarim basin underwent a cooling history with the heat flow of 55–65 mW/m2 in the Cambrian decreasing to the present-day of 40–50 mW/m2. The Meso-Cenozoic thermal history of the Bohai Bay basin experienced four evolutionary stages with two heat flow peaks in the late Early Cretaceous and in the Middle to Late Paleogene, which correspond to the destruction peaks of the eastern NCC and had heat flow values of 82–86 mW/m2 and 81–88 mW/m2, respectively. The Sichuan basin was stable with heat flow value of less than 65 mW/m2 from the Late Sinian to Late Paleozoic, and the heat flow increased rapidly to the peak value (75–100 mW/m2) at the end of Early Permian by thermal effect of the Emeishan mantle plume. From Mesozoic to present, the heat flow decreased to the present value (60–70 mW/m2). In addition, the comparation of thermal characteristics of typical cratons around the world, including heat flow, thermal history, lithospheric thermal structure and thermal lithospheric thickness, also have been caried out. The differential thermal histories of Tarim and Sichuan basins resulted in the different thermal evolution of Cambrian source rocks. This study may provide some new geothermal evidence for hydrocarbon generation and phase distribution of oil and gas in the deep and/or ultra-deep basin. Thermal regime and thermal history of typical sedimentary basins in three typical cratons of China underwent completely different evolution. The Tarim basin underwent a cooling history, the Bohai Bay basin experienced four evolutionary stages with two heat flow peaks, and the Sichuan basin was stable with heat flow but to a peak at the end of Early Permian. Nansheng Qiu, Chang Jian, Zhu Chuanqing, Liu Wen, Zuo Yinhui, Xu Wei, Li Dan. [Display omitted] • Three typical cratons of China show great differences in heat flow and deep-temperature. • Three typical cratons of China show great differences in lithospheric thickness from 76–170 km. • Thermal histories of Bohai Bay, Sichuan and Tarim basins are summarized. • Thermal regime between stable and destabilized cratons are compared. • Three thermal evolution patterns of source rocks are obtained. [ABSTRACT FROM AUTHOR]

The lamellation fractures in marine shales are important to the accumulation and preservation of shale gas, whose characteristics and controlling factors are still unclear. This paper focus on the characteristics descriptions and controlling factor analyses based on core observations, thin sections, and scanning electron microscope (SEM) experiments. The marine shales of Paleozoic Wufeng Formation and Longmaxi Formation in the Fuling Area of Eastern Sichuan Basin are taken as an instance. The lamellation fractures are occurring along the direction of the lamellations, partially of them curved, bifurcated, and converged. The apertures of fractures typically range from 1 to 500 μm. Only a few (<1%) lamellation fractures are filled with quartz, calcite, pyrite, and bitumen. After a series of analyses, developments of lamellation fractures are controlled by total organic carbon (TOC), brittle minerals, laminae, and pyrite. (1) The organic matters control the formation and evolution of lamellation fractures by generating gas and resulting in overpressure. An increase in the TOC content of 1% can increase the lamellation fracture density by 0.26 cm-1. (2) Brittle minerals, especially authigenic quartz, is also an important controlling factor to the development of lamellation fractures. When BI increases by 10%, the lamellation fracture density increases by 19%. (3) Besides, siliceous and carbonate laminae in the shale are more suitable for lamellation fractures to develop. When the laminae density is smaller than 4 cm−1, it is easier to develop lamellation fractures with higher laminae density. However, too densely-distributed laminae will suppress the formation of lamellation fractures. (4) Higher pyrite content is good for the development of lamellation fractures. Lamellation fracture density will increase by 9%, with pyrite content increased by 1%. For the shale at the bottom of the Wufeng Formation - Longmaxi Formation, lamellation fractures develop extensively due to the high TOC and pyrite content, great brittleness, and moderate laminae density. The density of lamellation fractures decreases from the bottom to the top. • Quantitative characterize about development characteristics of the lamellation fractures. • The lamellation fractures is controlled by brittle mineral, TOC, laminae and pyrite. • TOC is the main one that affects the development of lamellation fractures. • Clarify vertical distribution characteristic of lamellation fractures in the Wufeng-longmaxi Fm. [ABSTRACT FROM AUTHOR]

• CO 2 and SRB were the main factors of shale gas pipeline corrosion and perforation. • Pre-cultured with culture medium increased the corrosion rate of the steel, and SRB catalytic corrosion process. • CO 2 promotes bacterial film formation and accelerates corrosion. • Bacterial enrichment is the main cause of pitting corrosion. In the shale gas field in southern Sichuan Basin, the corrosion-induced failure has been observed. In this paper, first, the corrosion phenomenon was analyzed. Second, the causes of corrosion were analyzed thoroughly from the aspects of corrosive environment, materials, and corrosion products. Finally, the field water environment was simulated, and the result showed the following: SRB is one of the main causes of corrosion and perforation of shale gas pipelines, bacterial enrichment is the primary reason for local corrosion, and CO 2 promotes the formation of bacterial film and accelerates corrosion. [ABSTRACT FROM AUTHOR]

To determine the main hydrogeochemical processes affecting the migration and enrichment of arsenic in the high arsenic geothermal water in the Batang area of Sichuan Province, the hydrogeochemistry and whole rock geochemistry of groundwater and aquifer sediments were studied. The results show that the groundwater has an arsenic concentration of 3.1 to 80.8 μg L −1, which is mainly present in the form of arsenate. The arsenic concentration in this groundwater system is correlated with the presence of fluoride ions and the temperature. The thermal storage temperature and cycling depth are significantly correlated with the arsenic concentration. The thermal storage temperature in the Batang area is relatively high (220 °C to 260 °C). When cold water mixing takes place, the temperature falls to 76.56–177.51 °C, the proportion of cold water mixing ranges from 67% to 79%, and the circulation depth reaches 1318.11 to 3443.37 m. The temperature of the groundwater, the competitive adsorption of HCO 3 −, and the pH level also affect the arsenic concentration. The above results indicate that the alkaline reducing environment in the Batang area of Western Sichuan is beneficial to the enrichment of arsenic in the groundwater. The desorption of the arsenic adsorbed on the surface of Fe oxide/hydroxide minerals is the main route by which arsenic enters the geothermal water. These results provide guidance for the exploitation and utilization of geothermal water in the Batang area. • Dear editor, • This is the highlight of my article. • Batang area in Western Sichuan is rich in geothermal resources, but the arsenic content of geothermal water exposed on the surface is high. This paper takes arsenic as the breakthrough point, analyzes the cause of formation of high arsenic geothermal water in Batang area of Western Sichuan from the cause of formation of arsenic in geothermal water, and comprehensively discusses the cause of formation of high arsenic geothermal water from the aspects of hydrochemical characteristics, sediment characteristics, heat storage temperature, circulation depth and cold water mixing in the study area, and finally obtains the geothermal genetic model of Batang area of Western Sichuan. • Best Regards. [ABSTRACT FROM AUTHOR]

In this paper, the original nature of organic matters is introduced for the first time to reevaluate the lower Permian (P 1) source rocks. The carbonate rocks in Maokou Formation (P 1 m) whose high organic carbon values were caused by external asphalt have poor hydrocarbon generation ability, but the argillaceous rocks in P 1 m have some, especially the recent discovered black shale in Gufeng deep-water facies in the north have good hydrocarbon generation ability. The black shale is 5–20 m thick and the measured average value of organic carbon can reach up to 7.24 wt%, which can greatly increase the hydrocarbon generation capacity in the north; The studies of natural gas sources of the lower Permian in eastern Sichuan basin show that the contribution of gas source is mainly Silurian. In the north, the lower Permian source rock is supplemented, while in the south, it's greatly affected by the coal-measure source rocks of Longtan Formation (P 2 l); Take the Wutan-1 well in Tanmuchang as an example to dissect the reservoir in syncline area. The Wutan-1 well has a tested daily production of more than 80 × 104 m3, and the paleotectonic evolution history shows that it was in the high position of the structure during the generation and expulsion peak of hydrocarbon. The fracture-vuggy lithologic reservoir of Wutan-1 well is favorable for hydrocarbon capture and later preservation. According to the above, the Tanmuchang syncline has a good spatio-temporal matching relationship, which is the key to hydrocarbon accumulation and exploration. This knowledge has expanded the exploration area of the Lower Permian Maokou Formation in eastern Sichuan, and more importantly, it brings much enlightenment to the exploration of the syncline areas in Sichuan basin and other basins at home and abroad. • The original nature of organic matters is introduced for the first time to reevaluate the lower Permian source rocks. • The black shale in Gufeng deep-water facies has hydrocarbon generation capacity in the north of the eastern Sichuan Basin. • The sources of natural gas in Maokou Formation are different between the north and the south in the eastern Sichuan Basin. • The syncline area of the Lower Permian Maokou Formation in eastern Sichuan has the potential for gas accumulation. [ABSTRACT FROM AUTHOR]

Stimulation of oil and gas volcanic reservoirs is quite topical, while particular stimulation mechanisms of various fracturing technologies applied to volcanic rocks need to be clarified. This paper explores volcanic rock sample fracture surfaces' morphology, the acid etching depth, and/or proppant embedment depth under propped, acid etching, and propped-etching. The conductivity is an important evaluation index for the effect of stimulation treatment such as fracturing and acid fracturing, therefore, fracture conductivity under different conditions, such as proppant size and concentration, acid concentration and activity, the separate or joint application of acids and proppant, was evaluated with the samples from Permian igneous in the Sichuan Basin, China. The results indicate that the reaction between acid and rocks is hindered by the complexity and heterogeneity of mineral distribution, forming discrete dissolution holes in local areas instead of flow channels. The maximum embedding depth was 67 μm without acid etching, while those obtained after gelling and cross-linking acid etching were increased by 2.3–3.2 times, reaching 178 and 227 μm, respectively. The etching depth of the samples with the acid can reach 1000 μm. By the effect on conductivity, the increasing order was as follows: acid etching fracture, propped-etching fracture, and propped fracture, while there was a slight difference in conductivities of propped and propped-etching fractures. Therefore, hydraulic fracturing with proppant provides the volcanic reservoir's most effective stimulation. Acid-carrying-proppant fracturing would also be a lucrative stimulation technology if natural fractures are developed and contain acid-dissolved minerals. Acid fracturing failed to form the main fracture with high conductivity, and therefore is not recommended. This study is considered instrumental in clarifying the mechanism of different stimulation methods and substantiating the most efficient development of volcanic reservoirs. The research results can provide a reference for the optimization of stimulation method and the design of treatment parameters of volcanic reservoir. • The morphology, etching, and embedment depth of volcanic rocks were tested. • Fracture conductivity under different experimental conditions was evaluated. • The stimulation mechanism of different stimulation methods is clarified based on the experiment results. • Hydraulic fracturing is considered the most effective technique for the volcanic reservoir. [ABSTRACT FROM AUTHOR]

Formation damage has become a major obstacle to the efficient drilling and economic development for tight carbonate reservoirs with multiscale pore system and plenty of sensitive minerals. This paper critically reviews the potential formation damage mechanisms associated with mineralogy and pore structure, and discusses the common formation damage of tight carbonate reservoirs. Reservoir mineralogy is closely related to fluid/stress-sensitivity damage, formation damage mechanisms of which including mineral dissolution and precipitation, swelling and dispersion, fine detachment and migration, deformation and creep are summarized, and linked to mineral compositions of carbonate reservoirs in Qaidam Basin and Sichuan Basin. Pore system of tight carbonate reservoirs consists of nano-intercrystal, micro-intergranular and oomoldic, and nm-to mm-scale dissolution pores and microfractures, resulting in the diversity of formation damage. Formation damage dependent on pore structure of carbonate reservoirs dominantly refers to fluid sensitivity, phase trapping, solid invasion and stress sensitivity. The commonly-known formation damage including fluid sensitivity, phase trapping and stress sensitivity of tight carbonate reservoirs is discussed in Qaidam Basin and Sichuan Basin. This review provides significant sights into the relationship between formation damage mechanisms and mineralogy and pore structure of tight carbonate reservoirs, and addresses the future work direction for formation damage control of tight carbonate reservoirs. • Formation damage mechanisms induced by reservoir mineralogy are critically reviewed. • Multiscale reservoir pore structures result in the diversity of formation damage. • Conventional formation damage occurred in tight carbonate reservoirs is evaluated. • Future work for formation damage control of tight carbonate reservoirs is indicated. [ABSTRACT FROM AUTHOR]

The Emeishan mantle plume is supposed to play an important role in the Permian thermal regime and source rock hydrocarbon generation evolution in the Sichuan Basin, Southwest China. In this paper, we provide new valuable insights into the spatial thermal effect of the Emeishan mantle plume to the Sichuan basin and maturity evolution of the Paleozoic source rocks. Cambrian core samples from four wells were selected for zircon fission track and zircon (U–Th)/He analysis in order to determine their thermal histories. Then the thermal histories of typical wells throughout the basin were obtained based on the above result and previous studies. According to the peak heat flow value (q), four Permian geothermal units were classified: a stratospheric heat flow unit (q ≥ 90 mW/m2), a high heat flow unit (80 ≤ q < 90 mW/m2), a medium heat flow unit (70 ≤ q < 80 mW/m2), and a normal heat flow unit (q < 70 mW/m2). The interpretation of the abnormal Permian heat flow indicates that the enormous heat flow anomalies with values of >20 mW/m2 occurred in the stratospheric and high heat flow units was mainly caused by the mantle plume, while the weak Permian thermal perturbation with heat flow anomalies of <15 mW/m2 in other two units was more likely associated with crustal thinning. The thermal effect of the Emeishan mantle plume may be contained within the stratospheric and high heat flow units. By comparing the maturation histories of the Paleozoic source rock, we identified the thermal effect on the maturity evolution. The thermal perturbation had no obvious impact on the maturity evolution of the Lower Permian and Lower Silurian Longmaxi Formation. Only the Lower Cambrian Qiongzhusi Formation within high geothermal unit suffered significant thermal effect of the mantle plume and matured rapidly during the end of the Early Permian. • Four Permian geothermal units in the Sichuan basin were first classified. • New insight for the spatial thermal effect of Emeishan mantle plume. • Formation mechanism of Permian heat flow anomalies was identified. • The effect of mantle plume on the maturity evolution of source rocks was characterized. [ABSTRACT FROM AUTHOR]

• Seismic vulnerability analysis of a masonry pagoda through FE simulations in Abaqus. • Good agreement between FE modal analysis and cantilever beam first mode formula. • Sensitivity analysis on the CDP material parameters for Pushover Analyses POs. • NLDAs that confirmed the collapse acceleration results given by POs. • Slenderness influence studied using taller/shorter pagodas with 3D models artificially created. As an important historical building type for human beings, ancient masonry pagodas have key research significance. They are widely diffused in China, and they are tower-like masonry structures, usually massive and tall. This paper takes the Longhu pagoda as a case-study: it was built in 1342 CE, and it is the only masonry pagoda from the Yuan Dynasty. It is located in the Sichuan Province (China), it has a square plane, and the height is about 33 m. This construction severely suffered the so-called "2008 Sichuan Earthquake". A full 3D model of the Longhu Pagoda has been obtained and subsequently meshed. The FE software Abaqus/CAE has been used for carrying out static analyses, pushover analyses and non-linear dynamic analyses. The material non-linearities have been taken into consideration employing the so-called Concrete Damage Plasticity (CDP) model available in Abaqus. Modal analyses have shown that FEM results and simplified cantilever model results may agree. Pushover analyses (POs) have been performed under different load conditions and along the four principal bending directions to estimate the global capacities and the corresponding collapse mechanisms. Non-linear dynamic analyses (NLDAs) allowed putting in evidence the accuracy of the results provided by the pushover analyses; besides, they gave helpful information about the crack propagation, confirming the damage reported on-site after the 2008 earthquake. The state of damage found and the related failure mechanisms have been deeply commented. Moreover, some sensitivity analyses have been performed to study the influence of some material parameters on the pushover results. Furthermore, two fictitious 3D models of the pagoda have been created by doubling and removing two floors to investigate the influence of the tower slenderness. The before mentioned analyses have also been performed on such models, and the impact of the slenderness on this structural typology has been studied. Finally, the kinematic theorem of limit analysis has been applied, and some values of collapse acceleration have been consequently computed using different a-priori established collapse mechanisms. The results have been compared with FE simulations results, and the ability of limit analysis to quickly predict the seismic vulnerability has been discussed. [ABSTRACT FROM AUTHOR]

• Integration of GPS and strong-motion data for more accurate coseismic displacement. • Novel model of fusing GPS and strong-motion data with baseline shift correction. • Better performance of the integrated model shown in 2017 Jiuzhaigou earthquake. Near-field coseismic displacement information is very important for seismological research. High-rate GPS and seismic sensors are mutually advantageous for capturing earthquake-induced coseismic displacements. The combination of them can help to improve the near-field observation results. In this paper, we propose a combined model of fusing GPS and strong-motion records by taking into consideration the corrections of baseline shift, and then apply a multi-rate Kalman filter to analyze the collocated GPS and strong-motion data. The performance of the proposed approach is validated using 1 Hz GPS data and 200 Hz strong-motion data collected within 150 km from the epicenter during the Ms 7.0 Jiuzhaigou earthquake occurred on August 8, 2017 in Sichuan Province, China (33.20°N, 103.82°E). It shows that the GPS displacements based on the Epoch-relative Positioning Approach well reflect the instantaneous motion state of stations during the earthquake, indicating that the maximum instantaneous displacement of SCJZ station is 3.2 cm in north and −2.0 cm in east, and the permanent displacement of SCSP station is −0.6 cm in north. More accurate and reliable broadband displacements less than 1 cm are obtained by the combination model, which provide the full spectrum of the seismic motion. The integrated displacements have more characteristics of strong-motion results in the early stage of the earthquake with less noise, and in the strong shaking period, tightly bound by the GPS displacements, the integrated displacements will not diverge, and thus accurately record the long-period information of seismic waves. [ABSTRACT FROM AUTHOR]

Details of the Lower Cambrian succession of the newly-discovered intraplatfrom basin of the Yangtze Platform (South China), source rocks of the giant Ediacaran-Cambrian gasfields of the Sichuan Basin, including its stratigraphic framework, redox and organic matter accumulation histories, remain unresolved. This paper describes results of a petrological and geochemical investigation of Lower Cambrian strata near the center of the Sichuan Basin with the goal of elucidating those processes that controlled the sedimentary history of the succession. We recognize two intervals of organic-rich source rocks deposited in the intraplatfrom basin, including the Maidiping Formation and overlying Qiongzhusi Formation. The Maidiping accumulated in a carbonate platform setting during Fortunian-Early Stage 2 time (~541–526.5 Ma) and comprises a variety of rock types, including carbonate, chert, phosphorite, shale, and Mn-ore layers. Total organic carbon (TOC) value ranges from 0.47 to 5.06 wt.%; the highest quality source rocks are found in its lower member. The Qiongzhusi Formation was deposited as part of a clastic shelf during Middle Stage 2-Middle Stage 3 (~526.5–515 Ma) time. This unit is dominated by shale and argillaceous siltstone and displays TOC values varying from 0.30 to 4.28 wt.%. The most organic-rich deposits are found in its lower and upper members. Redox and hydrographic proxies suggest that the intraplatfrom basin was dominated by a strongly restricted environment and anoxic bottom water conditions that experienced intermittent episodes of euxinic or dysoxic-oxic conditions during the Fortunian-Middle Stage 3 time. However, bottom water conditions appear to have been oxic during Late Stage 2 time. Accumulation of Lower Cambrian source rocks across the Yangtze Platform appears to have been closely linked to depositional setting. Our findings suggest that organic matter accumulation in the intraplatfrom basin was fundamentally redox-controlled whereas productivity exerted the greatest control on deposition of organic matter near the slope-deep basin of the Yangtze Platform. In summary, Early Cambrian high-quality source rocks preferentially accumulated in topographic lows, including the intraplatfrom basin and slope-deep basin, an association useful to targeting conventional and unconventional hydrocarbons in the Sichuan Basin. • Stratigraphic framework of the Lower Cambrian deposits in an intraplatfrom basin on the Yangtze Platform were established. • The intraplatfrom basin was dominated by anoxic bottom water with intermittent episodes of euxinic/dysoxic-oxic conditions. • A model depicting controls on OM accumulation across the Yangtze Block during the Early Cambrian was proposed. [ABSTRACT FROM AUTHOR]

The Lower Cambrian Qiongzhusi Formation source rock is one of the main sources of oil and gas in the Sichuan Basin. Owing to the controversial thermal history and the complex structural pattern in the Sichuan Basin, it is difficult to characterize the differences in maturity evolution and the timing of hydrocarbon generation periods of Qiongzhusi hydrocarbon source rocks in different tectonic zones. Based on the comprehensive analysis of the previous thermal history and denudation studies from the tectonic units of the basin, the thermal histories and denudation amount in main period of tectonic movement of a five-part tectonic development are obtained in this paper. Although the thermal history of different tectonic units varies, generally, the heat flow increased slowly in the early Paleozoic, and it experienced a peak heat flow at the end of the Middle Permian and decreased subsequently. Based on new thermal history and denudation data, the maturation of the Lower Cambrian Qiongzhusi Formation source rocks in the Sichuan Basin were modeled and their evolution can be classified into three patterns, which are: (1) continuous heating pattern in southern Sichuan, (2) Silurian-Permian heating cessation pattern in western Sichuan and northwest central Sichuan, and (3) Silurian-Permian and Triassic heating cessation pattern in the central uplift, northern structural zone and western part of the eastern structural zone. In addition, the key hydrocarbon generation periods of different tectonic units were determined in this study. Tectonic and sedimentary burial, together with high heat flow values during the Late Permian, were the main factors controlling levels of thermal maturity and thermal evolution models of the Qiongzhusi Formation. The present-day thermal maturity of the Qiongzhusi Formation depends on the thermal history and maximum burial depth before uplift in Late Cretaceous. However, the maturity evolution pattern affecting the key hydrocarbon generation stage was mainly related to the burial histories of source rocks in the Paleozoic. The thermal modelling of this study provides new evidence for the source rock evolution and new insight into Lower Paleozoic shale gas. • Thermal history, denudation amount and process of different tectonic units are summarized. • Maturity evolution and key HC generation periods of the Qiongzhusi Formation are obtained. • Three thermal evolution patterns of source rocks are classified. [ABSTRACT FROM AUTHOR]

Most developing countries in the world face the common challenges of reducing air pollution and advancing the process of sustainable development, especially in China. Air pollution research is a complex system and one of the main methods is through numerical simulation. The air quality model is an important technical method, it allows researchers to better analyze air pollutants in different regions. In addition, the SCB is a high-humidity and foggy area, and the concentration of atmospheric pollutants is always high. However, research on this region, one of the four most polluted regions in China, is still lacking. Reviewing the application of air quality models in the SCB air pollution has not been reported thoroughly. To fill these gaps, this review provides a comprehensive narration about i) The status of air pollution in SCB; ii) The application of air quality models in SCB; iii) The problems and application prospects of air quality models in the research of air pollution. This paper may provide a theoretical reference for the prevention and control of air pollution in the SCB and other heavily polluted areas in China and give some1inspirations for air pollution forecast in other countries with complex terrain. [Display omitted] • Current situation of air pollution in the Sichuan Basin of China is reviewed. • The development and classification of air quality models are summarized. • Application of air quality models in the study of Sichuan Basin air pollution are discussed. • Problems in the application and future research directions of air quality models are provided. [ABSTRACT FROM AUTHOR]

Shale gas development in the Sichuan-Chongqing region in China has experienced a high level of casing deformation or failure during hydraulic fracturing treatment, which has resulted in significant productivity decline and economic losses. This problem has motivated many studies in the literature but focusing on the shearing deformation using the finite element method. This paper categorizes the casing failure modes and mechanisms in the region and presents casing collapse laboratory results. The designed laboratory tests rendered us critical data points in casing deformation under different loading scenarios. For multiple stage hydraulic wells in the region, we propose to use a strain-based protocol for casing design instead of the current design based on maximum stress. • Present laboratory experiments on casing deformation due to shearing stress. • Propose a model to predict the maximum allowable stress for a casing tubular. • Update statistics on casing deformations and failures in the Changning-Weiyuan region. • Introduce one of a kind laboratory experiment setup for full size tubular testing. [ABSTRACT FROM AUTHOR]

The Large High-Altitude Air Shower Observatory (LHAASO) is being built at Haizi Mountain, Sichuan province of China at an altitude of 4410 m. One of its main goals is to survey the northern sky for very-high-energy gamma ray sources via its ground-based water Cherenkov detector array (WCDA). 900 8-inch photomultiplier tubes (PMTs) CR365-02-1 from Beijing Hamamatsu Photon Techniques INC. (BHP) are installed in the WCDA, collecting Cherenkov photons produced by air shower particles crossing water. The design of the PMT base with a high dynamic range for CR365-02-1, the PMT batch test system, and the test results of 997 PMTs are presented in this paper. [ABSTRACT FROM AUTHOR]

Since the existing models and algorithms cannot well deal with the traffic assignment problems under uncertain supply and demand conditions, this paper proposes a traffic assignment model based on cumulative prospect theory. Firstly, the cumulative prospect theory is extended on the basis of a large number of numerical analysis experiments and the road impedance function of road segments is improved. Then, by setting the reference point of fuzzy generalized cost and the reference point of staged dynamic risk degree of road segment, the comprehensive cumulative prospect value (CCPV) function is improved, a boundedly rational user equilibrium (BRUE) model under uncertain supply and demand conditions is constructed, and an isolation niche genetic simulated annealing algorithm (INGSAA) is designed to solve the model. Finally, taking the road network of the Sichuan-Tibet region in China as an example, the processes of boundedly rational equilibrium under the fixed and variable network structure are investigated, and the relevant parameters are analyzed. The research results verify that the BRUE model based on the extended cumulative prospect theory provides a good idea for solving the problem of traffic assignment under uncertain supply and demand conditions, which is of great theoretical significance and application value. • Comprehensive cumulative prospect value function is given with the preference of multiple reference points considered. • Impedance function is designed for the traffic segments after considering cost and uncertain network supply. • Isolation niche genetic simulated annealing algorithm is proposed to solve the model. [ABSTRACT FROM AUTHOR]

Unconventional oil and gas reservoirs are mostly characterized by unconnected pores and abnormal pore pressures. These conventional effective stress theories, such as Biot's theory, cannot display the quantitative relationship between unconnected pores' micro characteristics and the macro stress applied to the solid structure. These parameters related to the unconnected pores should be quantitatively incorporated in the effective stress formula. In this paper, two modified models were proposed to evaluate the solid framework's real effective stress and deformation. The effects of the unconnected pore pressure, unconnected porosity, and unconnected pore fluid's compressibility on effective stress and volumetric strain were theoretically investigated. It was found that the increase of unconnected pore pressure can decrease the effective stress and volumetric strain. For an abnormal high pore pressure formation, the growth of unconnected porosity can reduce the effective stress but increase the volumetric strain. The decrease of the unconnected pore fluid's compressibility can increase and decrease the effective stress and volumetric strain for abnormal low and high pore pressure reservoirs, respectively. Two case studies on the abnormal pore pressures induced by under-compaction and hydrocarbon generation were conducted. The results showed that the pore pressure exhibits significant increases when the unconnected pores and unconnected pore fluids are proactively compressed in the processes of under-compaction and hydrocarbon generation, respectively. The abnormal high pore pressures in these tight sandstone reservoirs in the Sichuan Basin, Tarim Basin, and Bohai Bay Basin can be theoretically generated when the pore space is compressed to 95%–84% of the initial pore space. The model can evaluate the effective stress and deformation for reservoirs with considerable unconnected porosities. In turn, it can also interpret the abnormal pressure generation induced by the changes of unconnected porosity and pore fluid's compressibility. • Two modified models are proposed to evaluate the real effective stress of the solid structure. • Effects of unconnected pores on the effective stress and volumetric strain are investigated. • Abnormal pressures under under-compaction and hydrocarbon generation are evaluated. [ABSTRACT FROM AUTHOR]

The Northwestern Sichuan Basin is a hot spot for natural gas exploration, and in recent years, many wells have obtained high-yield commercial gas flows in the Qixia Formation. However, due to the influence of foreland orogeny, the oil and gas in the Qixia Formation often have the characteristics of multisource filling, multistage accumulation and multistage transformation, which results in an unclear understanding of the gas source and the accumulation process. This paper uses the concept of sub-block research through carbon isotope and biomarkers analyses, to carry out gas-gas, gas-source and bitumen-source rock comparisons in different structural belts to determine the natural gas sources. On this basis, basin simulation and fluid inclusion analysis technology are used to determine the stage of hydrocarbon accumulation, and then the accumulation process is determined. Studies have shown that the gas source of the Qixia Formation are different in the different structural belts: (1) The natural gas from the Qixia Formation in the thrust nappe belt mainly originates from the Qiongzhusi Formation source rock; (2) The natural gas from the Qixia Formation in the hidden fault belt is a mixture of the source rock of the Qixia Formation and the source rock of the Qiongzhusi Formation; and (3) The natural gas from the Qixia Formation in the gentle belt mainly originates from the Middle Permian source rock and the Upper Permian Longtan Formation source rock. The Indosinian, Yanshania, and Himalayan movements all have great influence on the formation of the Qixia Formation reservoir in northwestern Sichuan, and the accumulation process of the different structural belts is quite different, but generally, the accumulation process of the different structural belts have experienced three stages: a primary oil pool stage, gas pool stage and reformation and definition stage. • Through sub-block research, gas source of the foreland thrust belt is studied. • Different gas sources cause differences in carbon isotopes. • Accumulation process of each structural belt is distinct. • The results have implications for exploration in complex tectonic areas. [ABSTRACT FROM AUTHOR]

Fractures gradually open under the action of fluid pressure in drilling shale gas reservoirs because of the existence of shale natural fractures, which leads to the leakage of expansible fractures. Induced fracture leakage is difficult to find and control in the early stage of drilling, resulting in great economic losses. The current model of induced fracture leakage pressure model is based on takes rock fracture criterion, which can only be used to judge whether the fracture is fractures created or not but cannot analyze the influence of fracture width change on leakage pressure after natural fracture of shale cracking. In addition, the model cannot control the occurrence of leakage. In this paper, the calculation method of fracture's width change under induced pressure is established. According to the field leakage rate data, a dynamic model of leakage pressure is established based on the parameters of time, leakage rate, fracture's width, fluid viscosity, and wellbore radius. The model is applied to calculate the dynamic change of leakage pressure on the Sichuan Shale Gas Field site and control the induced fracture's change to control leakage. Results show the following observations. (i) The fracture's width and leakage velocity of induced fracture increase with the increase of leakage pressure. Blocking the leakage when any leakage is found on the site is not advisable because it can increase the fracture's width artificially and increase leakage. (ii) The critical value of the fracture's width may cause severe leakage. When the leakage's differential pressure remains unchanged, the relationship between the fracture's width and leakage velocity refers to the power exponent change. The method of controlling the leakage pressure and reducing the fracture's width that is less than the critical leakage fracture degree is adopted for the leakage of the shale gas drilling in the Longmaxi Formation field Jiaoshiba, which effectively reduces the leakage amount. Taking a particular project, for example, controlling leakage pressure of induced fracture is given to verify the feasibility of the method. • The calculation method of fracture's width change under induced pressure is established. • A modal of leakage pressure is established based on time,leakage rate,fracture's width,and fluid viscosity. • The method of controlling the pressure to reduce the fracture's width to control the leakage is established. [ABSTRACT FROM AUTHOR]

The prediction of pore pressure in subsurface formations is important for the estimation of hydrocarbon accumulation and for safe drilling activities. Typically, pore pressure is estimated from either well logs (e.g., P-wave velocity, resistivity) or seismic data (seismic velocities, acoustic impedance) using empirical relations based on compaction laws. Due to the high density and extremely heterogeneous physical properties, it's not feasible to calculated pore pressure in carbonate rocks with these empirical methods. The result of ultrasonic velocity measurements in carbonate rocks shows that velocity is affected by multiple factors, e.g., stress condition, porosity, rock composition, fluid composition, and other rock properties. It's practicable to predict pore pressure with velocity when other factors are kept constant or evaluated quantitatively. In this paper, a quantitative model to compute the elastic attributes as a function of pressure and petrophysical properties is proposed. The model as a rock physical model is based on the poroelasticity theory and describes the effect on the elastic property of stress conditions. The model is validated using laboratory measurements. A case study for this model application from the northeastern Sichuan Basin, including a set of well logs and borehole measurements is also presented. The pore pressure gradient in carbonate reservoirs is ranging from 0.99 to 2.13 MPa/100 m. The predicted result shows the relative error between model predictions and observations measured while drilling is from 0.60% to 10.22%. The method proposed in this study is effective for pore pressure prediction in carbonate formation. • Pore pressure in carbonate rocks is estimated by a new rock physical model. • The model is validated by laboratory measurements and tested using well-logging data. • The model can be considered as a new tool to predict overpressure in carbonate rocks. [ABSTRACT FROM AUTHOR]

Based on low-temperature thermochronological data (i.e., apatite fission-track (AFT) and (U–Th)/He (AHe)), structural evolution, burial and thermal history, this paper examines the relationship of multi-stage evolution between the upper Ordovician Wufeng and lower Silurian Longmaxi formations (i.e., the WL formation) and rapid exhumation at the Changning shale gas field in the southern Sichuan basin. AFT ages are generally young from southeast to northwest, decreasing from ca. 40 to 15 Ma while AHe single-grain ages range from ~35 to ~5 Ma. Inverse thermal histories show that a multi-stage cooling history with initial cooling began in the Late Cretaceous to early Cenozoic (middle Eocene), followed by accelerated rapid cooling in the late Cenozoic, with cooling rates of 2–4 °C/Myr across the Changning shale gas field. In particular, thermal models of samples in the western Changning area show a substantial increase in the cooling rates, i.e., from less than 1 °C/Myr to 3–5 °C/Myr in the Miocene. Integrated with inverse T-t models of low-temperature thermochronological data, the burial history indicates a four-stage thermal evolution of the WL Formation in the Changning shale-gas field: Early Mature from the middle Silurian to middle Permian, Middle Mature from the late Permian to Late Triassic, Late Mature from the Early Jurassic to Early Cretaceous, and Over mature since the middle Cretaceous, reaching a maximum burial depth of ~6000 m and maximum temperature of 190–200 °C at ca. 70–80 Ma. This evolution further suggests that a normal hydrostatic pressure index dominated the WL Formations in the Paleozoic. The gas generation and pressure index, however, have substantially increased since the Late Jurassic, particularly from the Early to middle Cretaceous, with a maximum pressure index of 2.1, which is indicative of the main shale gas accumulation and enrichment period in the WL Formation. Post-gas-generation structural deformation, uplift, and exhumation had a significant impact on shale gas enrichment, mainly through their influence on shale gas preservation. This suggests some relationships among the higher pressure coefficient of the WL Formation, the higher productivity and total gas content of the WL Formation, a weaker post-gas-generation structural deformation, and a weaker uplift, as indicated by the erosion and burial depth across the Changning shale gas field. Due to a significantly stronger cooling and uplift that occurred the in Late Cenozoic across the western Changning area, the pressure index decreased rapidly from ~2.0 to 1.0 with a normal pressure condition, indicating the destruction of the reservation condition in the WL Formation. • New low-temperature thermochronological data was from the SE Sichuan basin. • An accelerated cooling in the late Cenozoic was found. • Post-gas-generation deformation and exhumation controlled the shale gas enrichment. [ABSTRACT FROM AUTHOR]

• There were 315 shrinking cities from 2000 to 2015in China. • The PCR can effectively identify shrinking cities. • The number of shrinking cities in China will increase from 2015 to 2025. • The greatest negative impact of shrinking cities is the number of employees. Urban shrinkage became increasingly obvious during the process of rapid urbanization. It is important to understand the mechanism behind the formation and evolution of shrinking cities to realize urban transformation and sustainable development. This paper establishes a shrinking cities index to measure generalized urban shrinkage by using the population change rate at the county scale in China. First, on the spatial scale, the shrinking intensity and pattern distribution are analyzed. Second, on the temporal scale, the shrinking trajectories of shrinking cities are analyzed, and a trend is predicted for shrinking cities for 2020 and 2025 based on the gray model (GM (1,1)). Finally, economic, institutional, and social factors are selected to identify the major influences on the different shrinking trajectories using a spatial panel data model. The results show the following. (1) Between 2000 and 2015, shrinking cities in China were mainly distributed in four regions: the three northeastern provinces, the Shaanxi-Gansu-Ningxia region, the Sichuan-Chongqing region, and the middle and lower reaches of the Yangtze River. They thus appear to have connecting piece and axis distribution characteristics. (2) The dominant shrinking city types are slight and moderate shrinking, which together account for 80 %–90 % of all shrinking cities. These types have less severe or extreme shrinkage. Considering the different trajectories, temporary shrinking cities represent 75.26 % of all shrinking cities and predominantly occurred in 2010−2015. Episodic shrinking cities represent 19.74 % of all shrinking cities. Continuous shrinking cities represent 5.00 % of all shrinking cities and occurred in 2005−2015. (3) From 2015 to 2025, the number of shrinking cities is projected to be 272, with slight shrinkage accounting for 43.38 % of the total shrinking cities, and extreme shrinkage accounting for 4.78 %. Examining the spatial distribution of shrinking cities shows that they are mainly distributed in the three northeastern provinces, the Shaanxi-Gansu-Ningxia region, Xinjiang and the middle and lower reaches of the Yangtze River in the future. (4)Total GDP, GDP per capita, fiscal expenditures, employment, and built-up area have a significant impact on the population of shrinking cities. Among them, the total GDP has the largest impact, and the built-up area has the smallest impact. In addition, the total GDP, GDP per capita, fiscal revenue, and employment have a significant spatial spillover effect in temporary shrinking cities. This study provides empirical evidence to support Chinese policy makers in implementing urban sustainable development goals. [ABSTRACT FROM AUTHOR]

• CC plantation provided better inhabit environment and nutrient resources for development of soil fauna community. • Diversity of soil fauna community was highly associated with the variations of soil pH, OC, TN, AP and AK. • Soil AP and AN accounted for 57 % of the changes in soil fauna compositions. Soil fauna is vitally important to all soil ecosystems due to its significant role in humification and mineralization of plant residues, cycling of nutrients, improvement of soil porosity and structure, etc. Soil fauna is sensitive to land-use changes, fertilizer use, tillage, and land degradation. Tea production is one of the most important agricultural industries in China. However, very few studies have investigated the responses of soil fauna to tea tree (Camellia sinensis L.) cultivars; understanding these responses is crucial to maintaining soil health and biological diversity stability in such agricultural ecosystems. This paper concentrates on the impacts of tea trees on soil faunal community composition and diversity, forming the background of an evaluation of the land-use sustainability associated with various cultivars. Soil samples were collected at a depth of 0−20 cm from four major tea plantations in western Sichuan, China, with different cultivars (" Chuannong Huangyazao " - CH, " Fuding Dabai " - FD; " Chuanmu No.217 " - CM, and " Chuancha No.3 " - CC). The results showed that different tea tree cultivars in this study had significant (p < 0.05) influences on soil chemical properties. The soil at the FD plantation had the lowest pH, total nitrogen (TN), and available phosphorus (AP) but the highest available nitrogen (AN), while the soil at the CM plantation had the highest pH, AP and available potassium (AK). The highest soil faunal abundance (as indicated by the number of individuals per unit area) and community diversity (as indicated by Shannon and Margalef indices) occurred at the CC plantation. This result illustrated that compared to the other plantations, the CC plantation provided a more habitable environment and more nutrient resources for the soil faunal community development. The diversity of the soil faunal community was highly associated (p < 0.05) with variations in soil pH, organic carbon (OC), TN, AP and AK. The effects of tea tree cultivars on the rare soil faunal composition differed among the four tea plantations, but no significant difference in the composition of dominant and common taxa was observed. The relative abundance of the top ten soil faunal taxa was strongly associated with environmental variables. The two most important environmental factors (AP and AN) accounted for 57 % of the changes in soil faunal composition. This study highlighted cultivation and land-use management practices to promote soil health sustainability and soil faunal stability on land degraded by tea tree cultivars in western Sichuan, China. [ABSTRACT FROM AUTHOR]