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Objective To better interpret the geological information contained in geophysical logging data and expand the application scope of well logs in geology, Methods several typical cases of representative logging data are analyzed. This analysis seeks to enhance the use of well logs in geological research. Logging data can aid in the deployment of sidetracking wells by identifying tectonic occurrences and variations in their combination characteristics. Image log data also enable determintion of palaeocurrent directions and the identification of bidirectional provenance supply, thus providing refined and scientifically calibrated interpretations in alignment with geological understanding. Results Logging data, often regarded as the "eyes" of geologists, are advantageous for identifying and evaluating pores, caves, fractures, and other subsurface features. These data are crucial for discovering hydrocarbon reservoirs and facilitating the fine and continuous calculation of reserve parameters. The coupling relationships between mudstone resistivity, acoustic interval transit time, and in situ stress in logging curves can also be used to indirectly predict the quality of ultradeep reservoirs and hydrocarbon productivity. Moreover, combining geology, logging, and seismic activity allows for the delineation of hydrocarbon traps and supports oil and gas exploration and production. Conclusion The analysis of these typical cases assists geologists in better interpreting the geological information in logging curves and further broadens the application field and scope of geophysical logging data.

Objective The marine organic-rich shale of the Luzhai Formation of the northern Guizhong Depression is an important replacement field for shale gas exploration in the Dian-Qian-Gui Basin. At present, great breakthroughs have been made in the initial stage of exploration. So it is very important to evaluate the geological-engineering integration. Methods In this study, petrophysical data (e.g., core, thin section and scanning electron microscopy data) and logging data (e.g., conventional, imaging, nuclear magnetic resonance and array acoustic) are used to study the logging characteristics of geological and engineering "sweet spots" on the basis of core calibration logs and fine delineation of small layers, respectively. By superimposing the hydrocarbon source rock quality, reservoir quality and engineering quality, the coupling and optimization of geological and engineering "double sweet spots" are finally completed. Results The results show that the lithology of the shale in the first member of the Luzhai Formation is dominated by three types: siliceous shale, mixed shale and gray shale. The organic matter abundance and pore permeability are low, and the TOC content is between 1% and 2%. The biogenic silica content is low, and the source of silica is mainly the land source of debris supply. Shale gas is mainly stored in the pore spaces and microfractures associated with clay minerals, and adsorbed gas is the main source, while the free gas content accounts for a small proportion. The brittleness index ranges from 20% to 80% and is basically greater than 40%. The stress coefficient of variation ranges from 0.26 to 0.50, and the direction of the present maximum horizontal in situ stress is NNE-SSW. Conclusion The shale "sweet spot" section at the bottom of the third small layer was selected as the target window of the horizontal well, and the results of horizontal section drilling and gas measurement showed good results. The research results can provide theoretical guidance and methodological support for the evaluation of "sweet spot" logging and the selection of horizontal well target windows for shale gas wells.

Significance To systematically address problems related to the interpretation and evaluation of image logs and expand their application range in geology and engineering fields, firstly, the development history, data processing steps and interpretation process of image log acquisition series are reviewed, and then fine interpretation methods for image logs, constrained by "four levels" (direct interpretation of images, conventional logging constraints, core constraints and geological theory constraints), are proposed in this paper. Progress The image log facies models can be divided into seven categories: massive, banded, cross-stratified, spotted, convoluted, graded and symmetrical groove modes. Image logs can be used for core orientation, formation attitude acquisition, fracture evaluation, fault property analysis, in situ stress direction discrimination, sedimentary characteristic pickup, palaeocurrent direction discrimination, etc. Through the inverse calculation of Archie's formula, the image log data matrix can generate porosity spectra and apparent formation water resistivity spectra, which can be used for reservoir quality evaluation and fluid property identification, respectively. Slab images can reveal information such as sedimentary laminae, fine-grained sediment lamina textures can be identified, and high-resolution logging can be used to evaluate unconventional oil and gas reservoirs. Poro Tex image structure analysis technology can be used to identify the characteristics of reservoir spaces such as pores and fractures and to quantitatively calculate parameters such as porosity and fracture porosity. Therefore, it is widely used in comprehensive logging evaluations of highly heterogeneous carbonate reservoirs. Conclusions and Prospects These research results can help us to avoid misunderstandings in image logs interpretation and expand the application field of image logs.

Natural fractures within the lacustrine mixed shale oil reservoirs of the upper member of the Lower Ganchaigou Formation (E32) in the Ganchaigou area of the Qaidam Basin are pivotal to the exploration and development of shale oil and gas. This research investigates the developmental characteristics and controlling factors of natural fractures and their impact on the reservoir quality based on cores, image logs, thin sections, scanning electron microscopy observations, and experimental and production data. The results indicate that natural fractures in the E32 are categorized into tectonic fractures, diagenetic fractures, and abnormal high-pressure fractures. Tectonic fractures are characterized by a significant variation in dip angles, a wide range of apertures, low density, and a high filling degree. Diagenetic fractures typically exhibit low dip angles, small apertures, high density, and a low filling degree. Abnormal high-pressure fractures display chaotic orientations and complex styles, often consisting of filled fractures. The development and distribution of natural fractures are jointly influenced by mineral composition and brittleness, lamination structure, organic matter content and maturity, diagenesis, tectonic factors, and abnormal high pressure. A high content of dolomite, thin-bedded structures comprising carbonate laminae and felsic laminae, and abundant mature organic matter provide a favorable foundation for fracture development. Diagenesis, including dissolution, pressure solution, and mineral dehydration shrinkage, acts as a beneficial guarantee for fracture development. Tectonic locations near the hanging wall of faults and the core of anticlines are the main regions for fracture development. Abnormal high pressure is a crucial driving force for fracture development. Interconnected natural fractures of various types and scales significantly expand reservoir space and enhance pore connectivity and flow capacity, serving a vital function in maintaining high and stable production in lacustrine mixed shale oil reservoirs.

Study region: Loess Plateau (LP), China Study focus: This study investigated the spatiotemporal dynamics of vegetation drought on the LP using an improved temperature vegetation drought index (ITVDI) and explored its time-lag link with teleconnection factors. New hydrological insights for the region: Findings indicated that: (1) ITVDI is an effective tool for vegetation drought monitoring; (2) the vegetation droughts were primarily characterized by mild to moderate intensity, with spring manifesting the most expansive drought-stressed areas (about 61.89% of pixels); (3) approximately 71.69% of the region exhibited an increasing trend in vegetation drought, particularly in the Ordos Plateau and typical agricultural zones; (4) long-term dependence in vegetation drought patterns was observed in 70.65% of the region, characterized by forest-covered areas becoming wetter, crop-covered areas getting drier, and grass-covered areas shifting from dryness to wetness; (5) the lag time between ITVDI and Southern Oscillation Index (SOI) was generally less than four months (approximately 71.01% of pixels), while ITVDI lagged behind Pacific Decadal Oscillation (PDO) mostly between 6 and 8 months (around 75.77% of pixels); (6) extremum correlation coefficients effectively determined the lag time for vegetation drought behind large-scale circulation factors, considering both monotonic and non-monotonic relationships. These insights contribute to drought monitoring, risk assessment, and early warning system, thereby providing valuable support for drought mitigation and management strategies in the LP and similar regions worldwide.

Based on panel data for 30 provinces in China from 2000 to 2020, this paper uses entropy method to construct the integrated development indicators of energy Internet, and explores the impact of the development of the energy Internet on reducing carbon emissions in China and its internal transmission mechanism. The research results show that the development of energy Internet can significantly reduce regional carbon dioxide emissions, and increasing the use of renewable energy is an important mechanism for the comprehensive development of energy Internet to curb carbon emissions. Heterogeneity analysis shows that the emission reduction effect brought by the development of energy Internet is more remarkable in the regions with lower carbon emissions and western China. Furthermore, this paper finds that in the setting of the development of energy Internet, the development of renewable energy can promote natural gas consumption and advance energy conversion efficiency. The government’s emphasis on regional technology development has an external strengthening effect on carbon emission reduction. The research in this paper expands and diversifies carbon reduction pathways and provides reference for more developing countries to utilize the development of energy internet to achieve carbon reduction.

Abstract Nowadays environmental issues have been of great concern to the world, among which the problem of global warming caused by greenhouse gas emissions is particularly prominent. All countries in the Kyoto Protocol and the Paris Agreement have committed to control greenhouse gas emissions, and China, as the largest carbon emitter, has assumed a heavier burden. China has been striving to develop low-carbon technologies such as hydrogen, nuclear, wind, and solar energy, but the most attention should be paid to CCUS, which many scholars have high expectations that CCUS can help China reduce emissions to some extent. Therefore, this paper presents a prediction that CCUS can reduce 3.8% of carbon emissions for China in 2040 when CCUS emission reductions increase at a rate of 30%. The power and chemical industries could reduce carbon emissions by 2.3% and 17.3%, respectively.

Shale oil reservoirs, characterized by no productivity, are developed by horizontal drilling and volume fracturing, and it is very important to optimize shale fracable intervals based on engineering quality logging evaluation. The Paleogene Funing Formation shale in the Subei Basin is taken as a typical example in this study. A sonic scanner is used to calculate the elastic parameters, including Poisson's ratio and Young's modulus. Dynamic and static parameters are converted through core analysis data. The brittleness index and in situ stress are calculated according to Poisson's ratio and Young's modulus. In addition, a one-dimensional rock mechanics model was constructed with the shear slowness in a single well to calculate three components of in situ stress. Finally, considering the difference in the brittleness index and horizontal stress differences between different layers, brittleness index (BI) and (BI/(σH-σh)) were selected to describe the engineering quality. According to oil test data, the larger the brittleness index and the smaller the horizontal stress are, the higher the capacity after fracturing. A cross plot of the brittleness index and BI/(σH-σh) is established to divide the reservoir types. Consequently, there are two types, including I high productivity(engineering quality characterization parameters >2.2) and Ⅱ medium-low productivity (engineering quality characterization parameters < 2.2), in the Paleogene Funing Formation in the Subei Basin. High productivity produces oil after fracturing, which suggests that the classification results of sweet spots depending on the engineering quality characterization parameters are better. Logging evaluation of the engineering quality of shale oil reservoirs can provide a theoretical basis and technical guidance for optimizing favorable fracability and high productivity layers and provide scientific guidance for drilling and fracturing layer optimization of shale reservoirs.

The method and theoretical system of well logging geology have been widely used in the fields of basic geology, petroleum geology and engineering geology, but the different response sensitivity of different well logging series to geological information and the mismatching between geophysical properties of multiple well logs and geological genesis of rocks frequently result in misunderstandings in the research process of well logging geology. Therefore, it is in an urgent need to analyze the typical misunderstanding cases in the research of well logging geology and explore the corresponding scientific ideas and countermeasures. After analyzing the typical misunderstandings in the research of well logging geology, this paper investigates vertical resolution scale of various logging series and its contradiction with detection depth and illustrates the importance of the integration of different scales of data. In addition, the factor inducing “fake logging data” and its influence on interpretation evaluation are clarified and a set of ideas for well logging evaluation of geological interpretation is put forward. And the following research results are obtained. First, the typical misunderstandings in the research of well logging geology can be classified into two categories, namely geological body interpretation misunderstanding and reservoir property parameter calculation misunderstanding. Second, special geological phenomena, such as high-density and high-resistivity mudstone can lead to logging data ambiguity, so attention shall be paid to petrophysical response mechanisms during geological logging interpretation. Third, to carry out well logging evaluation of unconventional oil and gas, it is necessary to integrate new technologies of electric imaging logging, dipole acoustic logging and nuclear magnetic resonance logging, and the calibration of core data and the integration of geological ideas can improve the interpretation accuracy. Fourth, In the process of borehole structural logging analysis, sedimentary response, geostress evaluation and fracture identification, geological ideas shall be integrated to avoid the logging interpretation misunderstanding caused by the same response of different geological phenomena in well logs. In conclusion, the dialectical and systematic thinking from geology to logging and then to geology, from practice to recognition and then to practice and from “a narrow view” to “a broad view” can provide a scientific ideas for the comprehensive research of well logging geology.

Bashijiqike Formation in Bozi-Dabei area develops deep and ultra deep tight sandstone reservoirs. It is urgent to reveal the main controlling factors of reservoir quality and establish a matching well logging evaluation method for high quality reservoirs. In order to quantitatively evaluate the diagenetic facies, based on the data of core, thin section, cast thin section and scanning electron microscope and etc., the petrology, physical properties, diagenesis types and intensity, diagenetic minerals and other characteristics of the tight reservoir of Bashijiqike Formation in Bozi-Dabei area were studied. Based on quantitative calculation of ompaction rate, cementation rate, dissolution pore content and comprehensive diagenetic coefficient, the diagenetic facies were classified according to characteristics of diagenesis intensity and its combination. The reservoirs can be divided into three types of diagenetic facies, i.e., medium compaction weak dissolution facies, carbonate cemented facies and compaction dense facies. Through the fitting analysis of thin section data and well logging data, the well logging calculation model of diagenetic comprehensive coefficient Cg was established, and the method of quantitative identification of reservoir diagenetic facies were established. The well logging data of Well X1, Well Y1 and etc were processed.The reliability of the model was verified by matching the identification results with physical property analysis and casting thin section. The establishment of well logging quantitative characterization method of diagenetic facies can provide guidance for "sweet spot" prediction.

Abstract Full‐Heusler alloys (fHAs) exhibit high mechanical strength with earth‐abundant elements, but their metallic properties tend to display small electron diffusion thermopower, limiting potential applications as excellent thermoelectric (TE) materials. Here, it is demonstrated that the Co‐based fHAs Co2XAl (X = Ti, V, Nb) exhibit relatively high thermoelectric performance due to spin and charge coupling. Thermopower contributions from different magnetic mechanisms, including spin fluctuation and magnon drag are extracted. A significant contribution to thermopower from magnetism compared to that from electron diffusion is demonstrated. In Co2TiAl, the contribution to thermopower from spin fluctuation is higher than that from electron diffusion, resulting in an increment of 280 µW m−1 K−2 in the power factor value. Interestingly, the thermopower contribution from magnon drag can reach up to ‐47 µV K−1, which is over 2400% larger than the electron diffusion thermopower. The power factor of Co2TiAl can reach 4000 µW m−1 K−2 which is comparable to that of conventional semiconducting TE materials. Moreover, the corresponding figure of merit zT can reach ≈0.1 at room temperature, which is significantly larger than that of traditional metallic materials. The work shows a promising unconventional way to create and optimize TE materials by introducing magnetism.

Low-contrast oil reservoirs have a complicated origin story that frequently results from the interaction of several different factors. The low-contrast oil reservoirs in the Daqing Oilfield’s SaPu intercalation in the Longxi Region are the main subjects of this study. This work investigates the petrophysical origins of these low-resistivity oil reservoirs through a series of carefully planned petrophysical experiments. The results showed that the main determinants of the low-contrast oil reservoirs in the SaPu intercalation were the conductivity of clay minerals and a high irreducible water saturation. A low clay conductivity had a significant effect, resulting in a significant reduction in the formation resistivity, even in circumstances with a low porosity and a low formation-water salinity. Moreover, the results from the NMR tests revealed that the irreducible water saturation in the core samples primarily ranged from 0.6 to 0.8, suggesting a significant prevalence. This work provides strong petrophysical indices for evaluating low-resistivity oil reservoirs in the SaPu intercalation and useful information for the petrophysical evaluation of similar reservoirs.

The lithofacies characteristics of the Qingshankou Formation (K2qn) shale in the Gulong Depression are crucial for oil exploration and development. This study investigates the K2qn shale lithofacies characteristics and their impact on reservoir physical properties using scanning electron microscopy (SEM), high-pressure mercury injection (HPMI), and logging quantification. The results indicate that the main minerals in K2qn shale are quartz, plagioclase, and clay. The sedimentary structures are classified into three types: laminated, layered, and massive. The K2qn shale lithofacies can be categorized into 12 types based on a combination of lithology and sedimentary structure. The main types are laminated clayey shale, layered clayey shale, and layered felsic shale. The larger the average pore size of the K2qn lithofacies, the stronger the heterogeneity of pore size distribution in space and the better the pore-to-throat connectivity. The impact of K2qn shale lithofacies on reservoir physical properties is mainly due to differences in lithology, complemented by variations in the sedimentary structural model. Under certain diagenetic or tectonic conditions, a layered sedimentary structural model of lithofacies may not increase reservoir permeability. Generally, felsic and carbonate rocks in tidal flat environments promote the development of shale with high permeability and porosity, while lithofacies deposited in static water environments below the wave base in lake basins typically exhibit low permeability and porosity. The physical properties of a reservoir are primarily influenced by the differences in pore throat characteristics resulting from variations in lithology.

Characteristics of pore structure are crucial to oil exploration and development in shale reservoirs, but practical evaluation of shale pore structure remains a longstanding challenge. In this study, based on nuclear magnetic resonance transverse relaxation time (T2) spectra under water-saturated and irreducible conditions, total pore space and moveable fluid space were skillfully determined. Meanwhile, multifractal spectra were used to characterize T2 distributions of total pore space and movable fluid space. The results show characteristic parameters of high probability measure areas of multifractal spectra (multifractal parameters) have strong negative correlations with T2 geometric mean value, and average radii of pore and throat increase with a decrease in the multifractal parameters, indicating the shale reservoirs with low values of the multifractal parameters may have good pore structure. Moreover, clay mineral content has strong positive effects on the multifractal parameters. In contrast, (quartz+feldspar) mineral content negatively influences on the multifractal parameters. Finally, new accurate models for permeability estimation in core scale and well-logging scale of shales are both proposed based on the multifractal parameters, which are also applicable for the other reservoirs. Overall, this study is important and timely for evaluating pore structure and predicting permeability in shale reservoirs.

In natural micro-nanoscale porous media, the movable fluid porosity can effectively represent storage and permeable properties, but various mineral compositions have complicated effects on it. Taking saline lacustrine shale as an example, this study researched the effects of mineral composition on movable fluid porosity, based on nuclear magnetic resonance (NMR), focused ion beam (FIB), and x-ray diffraction (XRD) experiments. The results show that movable fluid porosity exhibits a stronger dependence on porosity than movable fluid saturation does. Micropores (1000 nm) are mostly developed in silicate and gypsum minerals, and have a highly heterogeneous distribution. In contrast, carbonate intercrystalline pores are dominated by mesopores (100−1000 nm), and behave strongly heterogeneously. Many mesopores play a positive role in generating highly movable fluid porosity, but the development of micropores and macropores is not conducive to an increase in movable fluid porosity. Overall, a significant negative effect is observed between silicate mineral content and movable fluid porosity, and carbonate mineral content has a strong positive effect on movable fluid porosity, whereas movable fluid porosity exhibits a relatively small reduction with an increase in the gypsum.

Abstract Fracture detection and in‐situ stress determination via well logs are important for exploration and exploitation of subsurface hydrocarbons. Cores, thin sections, and image logs are used to describe and interpret the subsurface fractures and in‐situ stress in the Paleogene Dongying sandstones in Nanpu Sag, Bohai Bay Basin, China. The maximum horizontal stress (SHmax) indicates a nearly east‐west trend according to the borehole breakouts and drilling‐induced fractures. Natural fractures in the Dongying sandstones are classified into: (1) open fractures and (2) closed fractures. The cement‐filled (closed) fractures are commonly detected by image logs as bright discontinuous sinusoidal waves due to resistive filling materials, while the open fractures are evident on image logs appearing as dark sine waves. The open fractures are of dominantly high dip angles, and the rose diagrams confirm the presences of two sets of fractures: northwest‐southeast and northwest‐southeast orientation. Fractures with strikes approximately parallel to the SHmax have good connectedness, making a significant contribution in hydrocarbon production. In addition, the oil‐bearing layers are mainly associated with the intervals with open fractures. The presence of natural fractures provides important pore spaces and fluid flow conduits. Insights can be provided into the subsurface fracture (natural and induced) detection and characterization using image logs.

Pore space of tight sandstone samples exhibits fractal characteristics. Nuclear magnetic resonance is an effective method for pore size characterization. This paper focuses on fractal characteristics of pore size from nuclear magnetic resonance (NMR) of tight sandstone samples. The relationship between the fractal dimension from NMR with pore structure and water saturation is parameterized by analyzing experimental data. Based on it, a pore structure characterization and classification method for water-saturated tight sandstone and a water saturation prediction method in a gas-bearing sandstone reservoir have been proposed. To verify the models, the fractal dimension from NMR of 19 tight sandstone samples selected from the gas-bearing tight sandstone reservoir of Shahejie Formation in Nanpu Sag and that of 16 of them under different water saturation states are analyzed. The application result of new methods in the gas-bearing tight sandstone reservoir of Shahejie Formation in Nanpu Sag shows consistency with experimental data. This paper has facilitated the development of the NMR application by providing a non-electrical logging idea in reservoir quality evaluation and water saturation prediction. It provides a valuable scientific resource for reservoir engineering and petrophysics of unconventional reservoir types, such as tight sandstone, low porosity, and low permeability sandstone, shale, and carbonate rock reservoirs.

Water shortages have always been the primary bottleneck for the healthy and sustainable development of the ecological environment on the Loess Plateau (LP). Proper water resource management requires knowledge of the spatiotemporal characteristics of precipitation frequency. This paper employed the gridded precipitation dataset obtained from the China Meteorological Data Service Centre to present a spatially explicit characterization of precipitation frequencies in tandem with their return periods on the LP based on the L-moment method. The 60% and 80% of the mean annual precipitation from 1981 to 2010 were synonymous with severe and moderate droughts, respectively. Droughts occurred more frequently in the northwest than in the southeast of the LP. Moreover, the frequencies of moderate drought showed a slight difference throughout the area, while those of severe droughts demonstrated considerable differences between the northwestern arid zone and the southeastern semi-humid zone. The maps associated with various return periods of precipitation deficits can be used to produce drought risk maps together with drought vulnerability maps. These findings could also provide useful information for drought management, water resource management and the development of food security policies.

To overcome the low efficiency of conventional confocal Raman spectroscopy, many efforts have been devoted to parallelizing the Raman excitation and acquisition, in which the scattering from multiple foci is projected onto different locations on a spectrometer’s CCD, along either its vertical, horizontal dimension, or even both. While the latter projection scheme relieves the limitation on the row numbers of the CCD, the spectra of multiple foci are recorded in one spectral channel, resulting in spectral overlapping. Here, we developed a method under a compressive sensing framework to demultiplex the superimposed spectra of multiple cells during their dynamic processes. Unlike the previous methods which ignore the information connection between the spectra of the cells recorded at different time, the proposed method utilizes a prior that a cell’s spectra acquired at different time have the same sparsity structure in their principal components. Rather than independently demultiplexing the mixed spectra at the individual time intervals, the method demultiplexes the whole spectral sequence acquired continuously during the dynamic process. By penalizing the sparsity combined from all time intervals, the collaborative optimization of the inversion problem gave more accurate recovery results. The performances of the method were substantiated by a 1D Raman tweezers array, which monitored the germination of multiple bacterial spores. The method can be extended to the monitoring of many living cells randomly scattering on a coverslip, and has a potential to improve the throughput by a few orders.

Frequent droughts induced by climate warming have caused increasing impacts on the vegetation of the Loess Plateau (LP). However, the effects of drought on vegetation are highly dependent on when the drought occurs and how long it lasts during the growing season. Unfortunately, most of the existing drought indices ignore the differences in the drought effects on different vegetation growth stages. In this study, we first established a phenology-based vegetation condition index, namely weighted vegetation condition index (WVCI), which accounts for the differences in vegetation sensitivity to drought by assigning specific weights to different phenological stages of vegetation. Then, we used the WVCI to reveal the temporal and spatial variations in vegetative drought from 2001 to 2019 over the LP from the aspects of drought frequency, trend and relative deviation. The results showed that (1) the LP experienced frequent droughts during the study period, but mainly mild and moderate droughts. The drought frequencies decreased from southeast to northwest, and extreme droughts rarely occurred in mountainous areas and plains. (2) The droughts in most areas of the LP tended to ease, and only a few areas in the Hetao Plain, Ningxia Plain and Fenwei Plain showed an increasing trend of drought. (3) After 2012, the departure percentage of WVCI in most areas of the LP was positive, indicating above-average vegetation conditions. (4) Compared with the well-established vegetation condition index, the WVCI proved to have the ability to monitor and assess vegetative drought on an annual scale in the LP. As a result, our research could help develop and implement drought-resistance and disaster-prevention measures on the LP.

Abstract Tight gas sandstone samples are imaged at high resolution industrial X-ray computed tomography (ICT) systems to provide a three-dimensional quantitative characterization of the fracture geometries. Fracture networks are quantitatively analyzed using a combination of 2-D slice analysis and 3-D visualization and counting. The core samples are firstly scanned to produce grayscale slices, and the corresponding fracture area, length, aperture and fracture porosity as well as fracture density were measured. Then the 2-D slices were stacked to create a complete 3-D image using volume-rendering software. The open fractures (vug) are colored cyan whereas the calcite-filled fractures (high density objects) are colored magenta. The surface area and volume of both open fractures and high density fractures are calculated by 3-D counting. Then the fracture porosity and fracture aperture are estimated by 3-D counting. The fracture porosity and aperture from ICT analysis performed at atmospheric pressure are higher than those calculated from image logs at reservoir conditions. At last, the fracture connectivity is determined through comparison of fracture parameters with permeability. Distribution of fracture density and fracture aperture determines the permeability and producibility of tight gas sandstones. ICT has the advantage of performing three dimensional fracture imaging in a non-destructive way.

Abstract: Based on the observation results of cores, structural analysis, sedimentary microfacies analysis, lithologic analysis and other analytical tests and logging data, the characteristics of lithology and lithofacies of the Member Chang7 tight oil reservoir of the Triassic Yanchang Formation in Heshui area are described and summarized and the criteria for identification of lithology and lithofacies by logging are established. The lithofacies in the Chang7 tight oil reservoir were classified into five types: fine sandstone deposited by sandy debris flow, turbidite fine siltstone, fine sandstone deposited by slump, semi-deep to deep lacustrine mudstone, and oil shale. The lithology and lithofacies in the Chang7 tight oil reservoir were characterized, both qualitatively and quantitatively, with electric logging and imaging logging and several means and methods, the response characteristics of different lithology and lithofacies were summarized through analyzing the image log and conventional log data, and the parameters characterizing sandstone's structures were used to quantitatively characterize the lithology and lithofacies, the criteria for identification of different lithology and lithofacies by logging were established. The vertical and horizontal identification and classification of lithology and lithofacies in a single well was then accomplished by processing the log data from each well, the results of lithology and lithofacies identification tally well with the results of formation testing. In-depth lithology and lithofacies analysis proves to be an important method of tight oil reservoir evaluation and “sweet spot” prediction. Key words: tight oil, lithology and lithofacies, logging identification, Ordos Basin, Heshui area, Chang7 Member

Uterine torsion of a nongravid uterus is rare, and proper diagnosis is challenging. Herein, we report a case of torsion of a large myomatous uterus in an 86-year-old woman who was presented with progressive renal failure and paralytic ileus. She was presented with abdominal discomfort, loss of appetite, and oliguria. A large myomatous uterus with broad calcification was identified when she underwent surgery to repair an umbilical hernia one year before the symptoms developed. Computed tomography revealed that one year later, the myomatous uterus significantly increased in size and the calcified lesion of the fibroid was largely displaced. She was also presented with paralytic ileus, and her general condition progressively worsened. Her serum creatinine levels were increased (3.5 mg/dL) and hemoglobin levels were low (8.5 g/dL). Emergency laparotomy revealed that the uterus was rotated 360 degrees clockwise at the level of the isthmus. The uterus was discolored, appearing dark red, and accompanied by broad congestion, and the cervix was elongated. The patient’s renal function and ileus recovered after a hysterectomy. In conclusion, torsion of a large myomatous uterus could become life-threatening in an oldest-old woman, and early release of the torsion is necessary to avoid serious complications.

The sedimentary facies, diagenetic facies and fracture facies of the Upper Triassic Yanchang Formation Member 8 (Chang 8) reservoir in the Jiyuan region were studied using core observation, thin section, logging and drilling data. On this basis, the petrophysical faices of Chang 8 oil layers were examined to evaluate the pore structure by classification and predict zones with high porosity and permeability. The petrophysical facies were divided according to the superposition and combination of sedimentary facies, diagenetic facies and fracture facies. A number of petrophysical facies of Chang 8 oil layers such as underwater distributary channel, dissolution of unstable components, high-angle fracture, were identified in this way. Four main categories of petrophysical facies were summed up according to the constructive and destructive impact of sedimentary facies, diagenetic facies and fracture facies on the reservoir property and pore structure. Since the reservoir quality index (RQI) is an optimal indicator for describing the reservoir micro-pore structure quantitatively, the value of RQI of different petrophysical facies was calculated respectively. So the classification and evaluation of Chang 8 reservoir pore structure in a single well were realized by the division of petrophysical facies combined with logging data. At last, the vertical and horizontal distribution of sedimentary micro-facies and diagenetic facies of each single layer of Chang 8 oil layers were mapped, the distribution of favorable petrophysical facies can be used to predict the zones with high porosity and permeability. Key words: petrophysical facies, sedimentary facies, diagenetic facies, fracture facies, pore structure, classification and evaluation, Ordos basin, Chang 8 oil layers

Two generations of carbonate cement as Type I (microcrystalline calcite and dolomite) and Type II (mainly Fe-calcite and Fe-dolomite) are recognized in Chang 8 sandstones, Ordos basin. Carbonate cement in Chang 8 sandstones is closely related to the dissolved carbon from thermal maturation of organic matters. Carbonate cement in the loosely packed framework grains precipitated shortly after deposition, and late-stage ferroan calcite and ferroan dolomite formed with progressive burial. The early diagenetic carbonate cement is partially to completely replaced by late-stage ferroan calcite and ferroan dolomite. Carbonate cement is much more commonly observed in sand bodies adjacent to Chang 7 source rocks. With increasing distance from the Chang 7 oil layers, the carbonate cement content gradually decreases. However, some tight carbonate cemented zones also occur at the sandstone-mudstone interfaces. Dissolution of Ca-feldspars by organic acids-rich fluids, together with clay mineral transformations such as illitization of smectite, would provide Ca2+ and Mg2+ ions for carbonate cementation. Organic acids and CO2 rich fluids would charge into the reservoirs with the hydrocarbons, and when the CO2 and acids were buffered by the framework grain dissolution, carbonate cement would precipitate with a decrease in CO2 concentration.

Poly-beta-hydroxybutyrate (PHB) can be formed in large amounts in Cupriavidus necator and is important for the industrial production of biodegradable plastics. In this investigation, laser tweezers Raman spectroscopy (LTRS) was used to characterize dynamic changes in PHB content—as well as in the contents of other common biomolecule—in C. necator during batch growth at both the population and single-cell levels. PHB accumulation began in the early stages of bacterial growth, and the maximum PHB production rate occurred in the early and middle exponential phases. The active biosynthesis of DNA, RNA, and proteins occurred in the lag and early exponential phases, whereas the levels of these molecules decreased continuously during the remaining fermentation process until the minimum values were reached. The PHB content inside single cells was relatively homogenous in the middle stage of fermentation; during the late growth stage, the variation in PHB levels between cells increased. In addition, bacterial cells in various growth phases could be clearly discriminated when principle component analysis was performed on the spectral data. These results suggest that LTRS is a valuable single-cell analysis tool that can provide more comprehensive information about the physiological state of a growing microbial population.

After the national "30.60" carbon peaking and carbon neutrality goals were proposed, Yulin City in Shaanxi Province, an important energy base in China, came under intense pressure to reduce emissions because of its rich fossil energy reserves and large number of coal chemical and coalfired power plant enterprises. As a result, it urgently needs to switch from high emission to low carbon. In this paper a four-dimensional seismic forward modeling is established to prove that the geological conditions of the area are suitable for CO2 geological storage and CO2 can be monitored in this area. Then the CO2 emissions of major industrial parks and counties in Shaanxi Province were summarized the Yulin City's current CO2 capture, utilization, and storage (CCUS) industrial chain was organized. Last but not least, the following recommendations were made for the development of the CCUS cluster in Yulin: (1) Yulin is appropriate for large-scale CO2 capturing activities due to its highly concentrated emissions and matured CO2 capturing technology. (2) Since the cost of transporting CO2 to its storage location by tank truck is significant, it is suggested that a pipeline be constructed to transport the gas in order to reduce costs. (3) Despite the promise of CO2-EOR (CO2-enhanced oil recovery) in Yulin, geological storage in a deep saline aquifer close by is now the preferred method due to the emission source's distance from the oilfield. (4) Two CO2 geological storage demonstration projects in Yulin City are still centered on oil displacement at the moment. It is necessary to conduct surveillance research on the volume of CO2 storage and use the CCUS method to define the accounting boundary. Yulin's geological sequestration of CO2 is now too small to satisfy the urgent requirement for significant emission reductions. It is vital to draw lessons from industrialized nations' experience, establish scientific research institutions for CO2 geological sequestration, and then design innovative and motivating policies in technology, supply chains, and commercial models that can extend the CCUS scale. [ABSTRACT FROM AUTHOR]