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By 2025, the total mileage of natural gas pipelines in China is expected to reach 163,000 km, placing urgent demands on the simulation technology for increasingly large-scale and more complicated pipeline networks. This paper describes the development of a new sectionalizing method, which is based on optimization strategy, for simulating large-scale and complicated natural gas pipeline networks. Based on analysis of the topological structures, the entire pipeline networks are decomposed into multiple sub-networks according to the connecting nodes between the adjoined pipelines. The sectionalizing method is then implemented by minimizing the residuals of conservation for continuity and momentum at the connecting nodes in isothermal mode. The hydraulic variables in each sub-network are obtained after the hydraulic variables at connecting nodes are updated. The calculation accuracy and efficiency of this sectionalizing method are demonstrated by comparison with a commercial software through three different test cases. It is shown that the maximum relative deviation of pressure of the method developed is within 2.5% of that calculated using the commercial software. In a 5 x 104 km test case with variable spatial step sizes, the computational efficiency is 2.1 to 3.2 times of that of the commercial software. The results of the three case studies suggest that this sectionalizing method is promising and suitable for application to large-scale complicate natural gas network simulation. [ABSTRACT FROM AUTHOR]

The development of hydrogen-blended natural gas (HBNG) increases the risk of gas transportation and presents challenges for pipeline security in utility tunnels. The objective of this study is to investigate the diffusion properties of HBNG in utility tunnels and evaluate the effectiveness of various ventilation mechanisms. The numerical simulation software Fluent 2023 R1 is applied to simulate and analyze the leakage of small holes in a HBNG pipeline in the natural gas compartment. By examining the leaking behavior of HBNG through small holes in different circumstances, we aimed to identify the most unfavorable operational situation for leakage. Subsequently, we analyzed the ventilation strategy for sub-high-pressure pipes at various pressure levels in this unfavorable condition. This study's findings demonstrate that blending hydrogen improves the gas diffusion capacity and increases the likelihood of explosion. The primary factors that influence the pattern of leakage are the size of the leaking holes and the pressure of the pipeline. The gas compartment experiences the most unfavorable working conditions for natural gas pipeline leaks when there are higher pressures, wider leak openings, higher hydrogen blending ratios (HBRs), and leaks in close proximity to an air inlet. When the HBR is 20%, the minimum accident ventilation rates for pressures of 0.4 MPa and 0.8 MPa are 15 air changes per hour and 21 air changes per hour, respectively. The maximum allowable wind speed for accident ventilation is 5 m/s, as regulated by China's national standard, GB 50838-2015. This regulation makes it difficult to minimize the risk of leakage in a 1.6 MPa gas pipeline. It is recommended to install a safety interlock device to quickly shut off the pipeline in the event of a leak in order to facilitate the dispersion of the substance. [ABSTRACT FROM AUTHOR]

The Niutitang Formation of the lower Cambrian (Є1n) is a target reservoir of shale gas widely developed in China's Middle-Upper Yangtze region, with the characteristics of being widely distributed, having a big thickness and highly organic carbon abundance. However, the exploration and research degree are relatively low. Based on extensive core sample, experimental test results, drilling, and field outcrop surveying, the shale gas generation capacity, gas content, and gas composition are discussed. The preservation conditions of shale gas are then systematically analyzed from the aspects of tectonic movement, fault development, structural style, and thermal evolution degree. The results show that the organic-rich shale with a thickness ranging from 40 to 150 m developed in the mid-lower part of the Є1n Formation, with the TOC content values ranging from 0.4% to 14.64%. While it has unfavorable characteristics of a high thermal evolution, with Ro values ranging from 1.92% to 5.74%, a low gas content and a high nitrogen content (70% wells). The Є1n shale gas has complex preservation conditions. The Є1n Formation has good roof-to-floor conditions, but after the main gas generating peak of the Є1n shale during the Jurassic–Cretaceous, the most intensive tectonic activity of the Yanshan movement resulted in poor preservation conditions (faults developed and cap rock fractured). The huge faults extended to the surface are formed due to tectonic movement in an extensional environment, and the structural style and development are the main factors affecting the preservation conditions of the Є1n shale gas. Additionally, the high thermal evolution of the Є1n shales also has a certain impact on the preservation conditions. Therefore, the stable area far from large faults (>2.0 km), with weak local tectonic activity and tectonic deformation, is the favorable area for shale gas preservation in the Є1n Formation. [ABSTRACT FROM AUTHOR]

The cross-regional renewable hydrogen supply is significant for China to resolve the uneven distribution of renewable energy and decarbonize the transportation sector. Yet the economic comparison of various hydrogen supply routes remains obscure. This paper conducts a techno-economic analysis on six hydrogen supply routes for hydrogen refueling stations, including gas-hydrogen tube-trailer, gas-hydrogen pipeline, liquid-hydrogen truck, natural gas pipeline, MeOH truck, and NH 3 truck. Furthermore, the impacts of three critical factors are examined, including electrolyzer selection, transportation distance, and electricity price. The results indicate that, with a transport distance of 2000 km, the natural gas pipeline route offers the lowest cost, while the gas-hydrogen tube-trailer route is not economically feasible. The gas-hydrogen pipeline route shows outstanding cost competitiveness between 200 and 2000 km, while it is greatly influenced by the utilization rate. The liquid-hydrogen truck route demonstrates great potential with the electricity price decreasing. This study may provide guidance for the development of the cross-regional renewable hydrogen supply for hydrogen refueling stations in China. • The techno-economics of six renewable hydrogen supply routes for hydrogen refueling stations are studied in China's context. • The cost impacts of electrolyzer selection, transportation distance, and electricity price are explored. • Natural gas pipeline H 2 blending route offers the lowest cost at 2000 km distance. • Gas-hydrogen pipeline route's cost is strongly influenced by its utilization rate. • Liquid-hydrogen truck route has the best economics when the electricity price is below 0.1 CNY/kWh. [ABSTRACT FROM AUTHOR]

Objective This paper discusses the quality requirements of ethane for the production of ethylene to determine the different quality requirements of ethane for different utilization and transportation ways, and further discusses the detection methods of different quality indicators of ethane in order to provide technical support for the relevant industry producing ethane from natural gas.Methods This paper mainly refers to the quality requirements of ethane products in the American Gas Processing Engineering Data Manual (GPSA) and the PetroChina enterprise standard of Q/SY 01027-2019 Technical specification of ethane extracted from natural gas. Based on these two documents, the quality requirements and indexes of gaseous and liquid ethane products in China were studied and discussed intensively, respectively. Results The ethane products may be divided into three classes according to their gaseous and liquid characteristics. Ethane products come from natural gas, so it is appropriate to use natural gas sampling method for sampling and to use related analysis and test standards of natural gas for its main quality determination. Conclusions At present, there are no national or industrial standards for ethane products in China. It is suggested that the relevant departments should faciliate the development process of national or industrial standards for ethane products to uniformly regulate the quality indicators, classification, inspection rules and delivery acceptance of ethane products. And then it can provide technical support for the implementation of ethane recovery projects, as well as promote the establishment of China’s ethane market and production system. [ABSTRACT FROM AUTHOR]

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The fluctuations of the Pipe-to-Soil Potential (PSP) in buried pipes are influenced by the geoelectric field induced by changes in the Earth's magnetic field, which can accelerate pipeline corrosion. Monitoring data of PSP along China's West–East Gas Pipeline near the lake indicates obvious tidal changes. This study proposes that the periodic movement of the conductivity boundary of the seepage area near the lake shore caused by tides is the fundamental cause of the tidal changes in PSP. The movement of the boundary changes the range of the H polarization of the geoelectric field, resulting in periodic changes in the PSP of the pipeline outside the seepage area. To investigate this mechanism, a dynamic boundary model of conductivity in the seepage area of Sailimu Lake in Xinjiang was established, and the characteristics of PSP at different distances from the boundary were analyzed using electromagnetic field finite element method and DSTL pipeline model. The study compared the simulation results of the model with the PSP data of the cathodic protection station and PSP monitoring station near Sailimu Lake, during a geomagnetic disturbance on September 23–24, 2016. The results of the study, as well as the corrosion of the test strips along the lake, verified the validity of the boundary change mechanism and model of the seepage zone. This study provides a theoretical basis for corrosion protection of pipelines near the lake's edge. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Employing a time series approach, Vector Error Correction Model, we investigate the price discovery in imported natural gas, liquefied natural gas (LNG) and pipeline, markets in China. The liberalisation of domestic natural gas markets and China's pricing reforms have induced systematic structural breaks. The present study explores the dynamic interrelationship between imported LNG and pipeline gas prices. Empirical results show that, before the market reforms in 2014, two markets were not cointegrated implying that both prices move somewhat independently. Over the series of market reforms between 2014 and 2019, both markets have started moving together (cointegrated). From winter 2020, LNG price increased abruptly partly due to LNG supply capacities and both prices are not cointegrated. In addition, empirical results show that LNG market is leading the imported natural gas markets in China and pipeline market is the major price adjuster, that is, a lagging market. [ABSTRACT FROM AUTHOR]

Based on literature research in combination with the practice of CO2 flooding and storage in Jilin Oilfield, this study assesses the key problems in CO2 flooding and storage, proposing the corresponding countermeasures from five aspects of CO2 gas source condition, namely geological condition evaluation, scheme design incoordination with other production methods, economic and effectiveness evaluation, together with dynamic monitoring and safety evaluation. The results show that CO2 flooding is the most economic and effective CO2 storage method. In eastern China, inorganic origin CO2 gas reservoirs are widely developed and are especially the most enriched in the Paleozoic carbonate rock strata and the Cenozoic Paleogene–Neogene system, which provide a rich resource base for CO2 flooding and storage. In the future, CO2 generated in the industrial field will become the main gas source of CO2 flooding and storage. The evaluation of geological conditions of oil and gas reservoirs is the basis for the potential evaluation, planning scheme design and implementation of CO2 flooding and storage. CO2 storage should be below the depth of 800 m, the CO2 flooding and storage effects in low‐permeability oil reservoirs being the best. CO2 geological storage mechanisms primarily consist of tectonic geological storage, bound gas storage, dissolution storage, mineralization storage, hydrodynamic storage and coalbed adsorption storage. The practice of CO2 flooding and storage in Jilin Oilfield demonstratesthat the oil increment by CO2 flooding is at least 24% higher than by conventional water flooding. The most critical factor determining the success or failure of CO2 flooding and storage is economic effectiveness, which needs to be explored from two aspects: the method and technology innovation along with the carbon peaking and carbon neutrality policy support. After CO2 is injected into the reservoir, it will react with the reservoir and fluid, the problem of CO2 recovery or overflow will occur, so the dynamic monitoring and safety evaluation of CO2 flooding and storage are very important. This study is of great significance to the expansion of the application scope of CO2 flooding and storage and future scientific planning and deployment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An accurate and stable prediction of the corrosion rate of natural gas pipelines has a major impact on pipeline material selection, inhibitor filling process, and maintenance schedules. At present, corrosion data are impacted by non-linearity and noise interference. The traditional corrosion rate prediction methods often ignore noise data, and only a small number of researchers have carried out in-depth research on non-linear data processing. Therefore, an innovative hybrid prediction model has been proposed with four processes: data preprocessing, optimization, prediction, and evaluation. In the proposed model, a decomposing algorithm is applied to eliminate redundant noise and to extract the primary characteristics of the corrosion data. Stratified sampling is applied to separate the training set and the test set to avoid deviation due to the sampling randomness of small samples. An improved particle swarm optimization algorithm is applied to optimize the parameters of support vector regression. A comprehensive evaluation of this framework is also conducted. For natural gas pipelines in southwest China, the coefficient of determination and mean absolute percentage error of the proposed hybrid model are 0.925 and 5.73%, respectively, with better prediction performance compared to state-of-the-art models. The results demonstrate the best approach for improving the prediction accuracy of the proposed hybrid model. This can be applied to improve the corrosion control effect and to support the digital transformation of the corrosion industry. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Because of the wide distribution of overland oil and gas pipelines, some pipelines will unavoidably pass through landslide-prone mountainous areas. Landslides may cause deformation or even damage to pipelines, affecting the normal working of the pipeline system. Therefore, it is necessary to study the multiple influence factors of pipeline deformation caused by landslides and establish a forewarning model for oil and gas pipelines buried in landslides. In the present research, the field investigation and a series of large deformation numerical simulations are conducted along four pipelines located in the southeast region of China. Results show that small soil landslides are the main types of landslides threatening the safety of pipelines, whose deformation degree mainly depends on the scale of the landslides and the location of the pipelines in the landslides. Through the investigation, the scale of landslides is the main factor determining the deformation of pipelines induced by landslides. Considering the variation of the scale of landslides, with the increase of the angles, thicknesses, and lengths of the landslides, the pipeline deformation keeps increasing. When crossing the landslides laterally, the pipeline buried in the leading edge of landslides is safer than in the tail edge. What is more, it is most dangerous when the pipeline is buried in the middle of a landslide. Considering the variation of the scale of landslides, including the longitudinal length, horizontal width, thickness, and slope of landslides, as well as the location of pipelines in the landslides, a piecewise forewarning model including those parameters was established based on the influence function for crossing pipelines in landslides. The proposed forewarning model can be used for monitoring and evaluating landslide geological disasters of pipelines and reduce the risk of pipeline landslide geological hazards in the monitored area effectively. [ABSTRACT FROM AUTHOR]

Objective In view of the helium-containing natural gas with developed pipeline network and poor quality in some areas of China, based on the investigation of the status quo of crude helium extraction process at home and abroad, a new helium extraction process from natural gas is proposed. Methods The process adopts low-temperature distillation method, and HYSYS software was used to simulate the process, and the thermodynamic analysis of the helium extraction process was carried out. Then, the influences of key parameters in the process on the helium recovery rate, crude helium purity, process energy consumption and exergy efficiency in the process was analyzed. The key parameters include the pressure of the helium extraction tower, the feed temperature at the top of the helium extraction tower, the feed temperature of the first-stage separator, the feed temperature of the second-stage separator, and the flow rate of the side draw stream. Results The simulation calculation results show that the recovery rate of helium in the process is 99. 06%, the product purity of crude helium is 80. 39%, and the total energy consumption is 994. 48 kW. The total exergy loss of the process is 713. 27 kW, and the exergy efficiency of the system is 28. 28%. Conclusions This process can achieve ultra-high helium recovery rate and high crude helium purity, and can provide reference and data guidance for natural gas helium extraction process units. [ABSTRACT FROM AUTHOR]

Gas gathering pipeline network system is an important process facility for gas field production, which is responsible for collecting, transporting and purifying natural gas produced by wells. In this paper, an optimization model for the layout of star-tree gas gathering pipeline network in discrete space is established to find the most economical design scheme. The decision variables include valve set position, station position and pipeline connection relation. A series of equality and inequality constraints are developed, including node flow balance constraints, pipeline hydraulic constraints and pipeline structure constraints. A global optimization strategy is proposed and an improved genetic algorithm is used to solve the model. To verify the validity of the proposed method, the optimization model is applied to a coalbed methane field gathering pipeline network in China. The results show that the global optimization scheme saves 1489.74×104 RMB (26.36%) in investment cost compared with the original scheme. In addition, the comparison between the global and hierarchical optimization scheme shows that the investment cost of the global optimization scheme is 567.22×104 RMB less than that of the hierarchical optimization scheme, which further proves the superiority of the global optimization method. Finally, the study of this paper can provide theoretical guidance for the design and planning of gas field gathering pipeline network. [ABSTRACT FROM AUTHOR]

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The completion of the natural gas pipeline 'Power of Siberia' in 2019 creates new dynamics in Eurasian trade. Russia's deepening ties with China present it with the opportunity to change its relationship with the European Union from monopsony to monopoly, thus gaining bargaining leverage. However, this argument goes both ways, being also applicable to Russo–Chinese affairs, with the European Union as the alternative option. The article concludes that Russia, while seriously strengthened by its developing energy relationship with China, will not endanger its status as a reliable supplier across Eurasia, since its nascent monopoly position depends on the existence of an alternative option. [ABSTRACT FROM AUTHOR]

Since the implementation of China's clean heating plan in 2017, the progress of natural gas replacing coal for heating is still not ideal. With the proposal of the goal of carbon neutralization and the impact of international war, the price, supply, and demand of natural gas have attracted attention. In case of gas shortage, reasonable schemes are required to be allocated to different industries and categories. Therefore, this research divides the gas field into four levels according to the social utility, and establishes the multi-objective distribution optimization model considering the social and economic benefits. The solution of the model is based on genetic algorithm and realized on MATLAB. Multi-objective optimization strategies and several constraints are used to make the algorithm's process of the search is continuously moving closer to the Pareto optimal front. Taking Beijing as an example, two scenarios are set to simulate and optimize, so as to verify the optimization effect of the model. Better quantitative results are created after reallocation of natural gas. The ideal scenario realizes 5.64% more social benefits than 2019 through additional allocation of 117.288 million cubic meters of reserve gas. The constraint scenario creates 0.67% more social benefits with only 0.07% decrease of the economic benefits. The conclusions show that allocating more gas to three main industries can improve the optimization effect and it is necessary to expand the supply of natural gas reserve volume. This paper provides a new perspective of natural gas allocation category and priority, providing theoretical and practical ideas for the planning of natural gas security emergency plan and the development of gas sales plan. [ABSTRACT FROM AUTHOR]

Although energy poverty has obtained wide focus in recent years, there is no consensus on the measurement of energy poverty. Given that China is experiencing socio-economic transformation as well as energy transition, this paper employed a total of 28 indicators, which representing three categories (energy service availability, energy consumption and generation cleanliness, and residential energy affordability and efficiency) that capture China's features as well as consider policy factors, to develop a new multi-dimensional energy poverty index by using entropy weight method. The result reveals that the energy poverty level has been improved nationwide for the period 2014–2019; three sub-indices also show downward trends while household energy affordability and efficiency suggests the fastest improvement; however, significant differences exist in energy poverty not only between urban and rural areas but also across provinces in China. Policy recommendations are as follows: continue to promote rural power grid renovation and upgrading and the construction of natural gas pipelines, increase clean energy support; encourage diversified development of rural energy supply methods, and provide more innovative and diversified green energy and financial products. • An integrated energy poverty index system for China was established. • A total of 28 indicators used in this paper are applicable to China's features as well as considering policy factors in China. • The energy poverty level has been improved nationwide from 2014-2019, and all three sub-indices show downward trends, but varies greatly between urban and rural areas and across geographic regions [ABSTRACT FROM AUTHOR]

Gob buried pipe is a common technological means for gas extraction. This method can effectively address the transfinite gas problems on the working face. However, it may induce spontaneous coal combustion in the gob. In this study, the disturbance effect of the gob buried pipe's entrance position on oxidation of residual coals in the gob is analyzed. A physical model with the same size as the 81307 fully mechanized caving face in the Baode Coal Mine in China is constructed. Then, the airflow leakage field and oxygen concentration field in the gob under different exploitation conditions are solved. Results demonstrate that extraction by buried pipe may change the airflow leakage field in the gob. Specifically, the gas penetration range into the gob is narrowed, which decreases the oxidation zone width in the gob to some extent. When the entrance is far from the working face, the return airway's oxidation zone is small. With the increase in the distance from the entrance to the working face, the boundaries of the return airway's oxidation zone also move backward, increasing risks. Combining with field practices, a gap of 100 m between the entrance and the working face can meet fire-resistance requirements of gob and decrease gas concentration at the corners of the return airway, achieving the best effect. The study could help to optimize gob buried pipe's entrance position, prevent spontaneous coal combustion, so as to guarantee the safety of mining. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate forecasting of natural gas load forecasting is of great practical significance to balance supply and demand of gas system. Load forecasting is categorized in long-term, mid-term and short-term. Among them, mid-term load forecasting that monitors monthly operations is of decisive significance to urban gas pipe network planning, gas engineering project construction and design. In this study, we adopt Prophet model that reflects the seasonal fluctuations and holidays influence to forecasting the monthly gas load of urban gas and compare the results with the other two forecasting methods such as autoregressive integrated moving average model (ARIMA) and exponential smoothing prediction method (ESM). The models were trained and tested on gas consumption data gathered in one central city in China from 2017 to 2021. The result shows that an increasing trend with an average growth rate between 10% and 20% year by year, a decreasing trend at an average rate of 14.9% on legal holiday. According to this study, the Prophet model has an excellent performance in monthly natural gas forecasting. [ABSTRACT FROM AUTHOR]

Natural gas pipeline projects in mountainous areas are inevitably affected by geological disasters such as landslides, which pose a serious threat to the safe operation of pipelines along the routes crossing landslide areas. In this paper, based on a pipe-landslide project in a mountainous area in southwest China, the interaction mechanism and failure evolution process of the landslide-pipeline system reinforced by two kinds of micropiles are studied through indoor large-scale physical model tests, and some suggestions on the support work of the pipe-landslide project are put forward according to the test results. It was found that the deformation process of the engineering system composed of landslide, micropile, and pipeline presents a high degree of synergy under the external force and mainly experiences four stages: initial deformation period, uniform deformation period, accelerated deformation period, and residual deformation period. The bending deformation of the perforated pipe micropile is large at the 1/4 position of the pile top from the pile bottom, and the deformation of the screw micropile near the sliding surface is serious. The pipeline welding port is the weak position of the pipeline; after the failure of the pile, the pipeline interface is first cracked, along the interface position along the two ends of the tear, and finally completely broken. The screw micropile cannot effectively resist the landslide thrust at a large load level, so the risk of pipeline damage is greater. The yield strength and ultimate strength of the perforated pipe micropile are greater than those of the screw micropile, and the perforated pipe micropile can still exert a certain residual resistance after reaching the ultimate bearing capacity, which has a beneficial effect on the reinforcement of the pipeline crossing the landslide system. The research results provide important reference value for landslide-pipeline treatment engineering. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To achieve China's carbon peak and carbon neutrality goals, conducting systematic research on the energy, economy, and emission factors that affect the sustainable development of society is of great significance. This paper first uses the vector error correction model (VECM)-based Granger causality test to analyze the joint causal relations and feedback correction mechanisms among energy consumption, economic growth, and CO2 emissions in China from 1980 to 2019 at the energy heterogeneity level; then, analyzes the decoupling effect of China's four major energy sources (coal, oil, natural gas, and electricity) and economic growth from the perspective of energy heterogeneity; finally, the Tapio decoupling elastic model is decomposed into the emission reduction elasticity and energy saving elasticity to analyze the decoupling causality chain of the economy, energy, and carbon emissions. The research results show that there is a long-term, two-way causal relation between coal consumption and CO2; coal consumption has a one-way causal relation with economic growth; and long-term, two-way causal relations exist between oil and CO2, natural gas and CO2, electricity and CO2, electricity, and economic growth. In addition, when energy consumption, economic growth, and CO2 emissions deviate from their equilibrium states in the short term, various energy consumption, economic growth, and CO2 emissions in the previous year will be adjusted by 19.5%, 0.6%, ..., 7.7%, and 3.4% to bring the nonequilibrium states back to the long-term equilibrium states. Furthermore, the energy-saving elasticity of China's total energy, coal, oil, and natural gas is the main factor affecting the corresponding decoupling elasticity, but the emission reduction elasticity of electricity has a stronger impact on the decoupling elasticity than the emission reduction elasticity does. [ABSTRACT FROM AUTHOR]

The paper is aimed at establishing a corrosion risk assessment model for the buried gas pipeline. To realize the forecast of the gas pipeline corrosion damage risks, the adverse factors of the safe operation were classified, and the index evaluation system of possibility of gas pipeline failure was established based on five first-level indicators and six second-level indicators. According to the index evaluation system, improved analytic hierarchy process (I-AHP) method was used to determine the weight of each indicator, and then the fuzzy comprehensive evaluation was proposed based on improved AHP. The calculation and analysis were carried out, and the membership function of the fuzzy comprehensive evaluation suitable for gas pipeline corrosion risk assessment was obtained, which had improved the practicability. Taking the buried gas pipeline network of Suzhou Industrial Park, China, as an example, the assessment was carried out. Some buried gas pipelines were randomly selected for excavation to verify the degree of conformity between the observation results and the calculation results. The results show that: the evaluation results of this method are consistent with the field detection results. In addition, the evaluation model established in this paper can provide a reference for the establishment of accident database and the management for the pipeline operation enterprise. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For the application of X80 pipelines in Northeast China, it is important to establish the correct cathodic protection (CP) potential. To achieve this, potentiodynamic polarization; electrochemical impedance spectroscopy (EIS); a slow strain rate test (SSRT); and a scanning electron microscopy (SEM) fracture morphology analysis were carried out for an X80 steel gas pipeline at several temperatures in Heilongjiang Province, China. The results show that the hydrogen evolution potential of X80 steel in soil at different temperatures was about −900 mV (vs. CSE). The generated hydrogen atoms can be adsorbed on the surface of the pipelines to reduce the surface energy, or they can be diffused into the substrate and accumulate to the critical concentration, inducing the decohesion between different structures and generating additional plastic deformation through dislocation motion. With the peak impedance potential as the minimum potential and the hydrogen embrittlement potential as the maximum potential, the CP potential of X80 steel in the soil at 30 °C, 45 °C, and 60 °C ranged from −900 mV to −1100 mV (vs. CSE), temperatures at which the X80 steel does not corrode or cause hydrogen embrittlement. [ABSTRACT FROM AUTHOR]

Hydrogen-blended electricity-gas integrated energy system (EG-IES) utilizes surplus renewable energy power generation to blends hydrogen into the natural gas pipeline network for achieve efficient and economical large-scale hydrogen consumption and long-distance transportation. While enhancing the coupling between the power grid and gas grid, the scheduling control of such a complex system becomes increasingly important. The paper presents a dynamic model of a hydrogen blended EG-IES with high renewable energy permeability, and a modeling method that considers distribution parameters of the natural gas pipeline is obtained by using the cell segmentation and calculating the blended gas composition in real-time to avoid the assumption of constant composition. After the validation against available operational data, a case study of the certain area of Central China is simulated. The coordinate control law is reasonably designed according to the dynamic characteristics of EG-IES and the objective of realizing the load increase within the hydrogen concentration constraint, and the PID is utilized as the benchmark to compare dynamic performance. The results demonstrate that the coordinated control based on the alternate adjustment control law has no overshoot and shorter adjustment time of p l and ε about 33% and 42% than benchmark on the large delay system. • Establish a dynamic hydrogen blended electricity-gas integrated system model. • Solve the distribution parameter characteristics of the natural gas pipeline network. • Dynamic simulation and verification of a real EG-IES in Central China was carried. • Analysis of the different coordinate control performance during the load up process. [ABSTRACT FROM AUTHOR]

The fundamental function of a natural gas pipeline network is to transport enough natural gas to users. Therefore, user characteristics should be considered in the formulation of the flow allocation plan of the pipeline network under accident conditions. However, user characteristics have usually not been considered in previous flow allocation models. In this study, a mixed integer linear programming model is developed to determine the optimal flow allocation plan of a large-scale and complex natural gas pipeline network under accident conditions, and the user characteristics are considered as well. The optimization objective is to maximize the weighted sum of the amount of natural gas transported to the consumers under accident conditions, and the weights of the natural gas users are obtained by user characteristics analysis. The model constraints include flow constraints, gas source supply capacity constraints, user demand constraints, pipeline transmission capacity constraints, pressure constraints, and pipeline hydraulic constraint. For the sake of model simplification, the hydraulic constraints are treated piecewise linearly. Furthermore, the model is set into a real-world situation, which is the natural gas pipeline network located in China, and the user characteristics are considered in the optimal flow allocation plan under accident condition. The impact of user characteristics is further investigated by calculating and comparing the flow allocation plan when considering and ignoring user characteristics. The study indicates that when user characteristics are considered, the natural gas pipeline network will tend to give higher priority to those crucial users. [ABSTRACT FROM AUTHOR]

The large amounts of emissions released by forest fires have a significant impact on the atmospheric environment, ecosystems, and human health. Revealing the main components of emissions released by forest fuel under different combustion states is of great importance to evaluate the impact of forest fires on the ecological environment. Here, a self-designed biomass combustion system was used to simulate the combustion of different parts (i.e., branch, trunk, and bark) of five tree species and branches, and three layers of surface dead fuel (i.e., litter layer, semi-humus layer, and humus layer) of three shrub species, in the Daxing'an Mountains, Inner Mongolia. The emission characteristics of the main gas pollutants (i.e., CO, CO2, HC, and NOx) and PM2.5 released under the two combustion states of smoldering and flaming, along with the correlation ratio among emission factors, were measured. The results show that the average amounts of emissions released by different trees and the three layers of surface dead fuel from a smoldering state are higher than those from the flaming state, while shrub combustion shows the opposite. The emissions released by trees, shrubs, and surface dead fuel from the flaming state are ordered from high to low as follows: CO2 > CO > HC > NOx > PM2.5; and from the smoldering state as CO2 > CO > HC > PM2.5 > NOx, indicating that the primary emissions under both conditions are mainly due to CO2, CO, and HC, while the emissions of NOx and PM2.5 are dependent on the combustion state—flaming promotes the emission of NOx, while smoldering promotes the emission of PM2.5. The average emissions of PM2.5 from the branches, bark, and trunks of Quercus mongolica are significantly higher than those of the other four tree species in the smoldering state, and the emissions of PM2.5 from the five tree species are ordered as follows: bark > branch > trunk. This study will help to further understand the impact of forest fires on the atmospheric environment and ecosystems in Northern China. [ABSTRACT FROM AUTHOR]

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As the natural gas pipeline network becomes larger and more complicated, a stricter requirement of computation efficiency for the large and complicated network transient simulation should be proposed. The adaptive time step method has been widely used in the transient simulation of natural gas pipeline networks as a significant way to improve computation efficiency. However, the trial calculation process, which is the most time-consuming process in time step adjustment, was used to adjust the time step in these methods, reducing the efficiency of time step adjustment. In order to reduce the number of trial calculations, and improve the calculation efficiency, an improved adaptive time step method is proposed, which proposes the concept of energy number and judges the energy number of the boundary conditions after judging whether the variation of the pipeline state is tolerable. A comparison between the adaptive time step method and the improved adaptive time step method in the restart process of natural gas pipelines and an actual operation of the XB section in China shows the accuracy, effect, and efficiency of the improved adaptive time step method. The results show that with the same accuracy, 27% fewer trial calculation processes and 24.95% fewer time levels are needed in the improved time step method. [ABSTRACT FROM AUTHOR]

The reverse distribution of renewable energy resources and load centers makes exploring the optimal transmission mode of long-distance and large-scale renewable hydrogen the key to solving the bottleneck of renewable hydrogen development. This study incorporates hydrogen pipeline (HGP), natural gas pipeline (NGP), and Ultra High Voltage (UHV) into an optimal planning model framework and analyzes the optimal transmission mode, quantity, network, and cost of large-scale renewable hydrogen in China. Constructing a sensitivity analysis framework, this study also investigates the optimal transmission mode changes under different scenarios. The results show that the optimal mode of large-scale renewable hydrogen transmission in the province is NGP, and 5.4% of supply level is the critical point to export renewable hydrogen inter-provincially. It switches to the combination of NGP and HGP when the unit transmission costs of these elements decrease to a certain proportion simultaneously or switches to HGP when the unit transmission cost of HGP decreases more than that of NGP. The complementary transmission mode of NGP and UHV is the optimal mode for inter-provincial transmission, and the HGP can be put into use for inter-provincial transmission only when the unit transmission cost of which is reduced to less than 25%. Jilin is the key node in the NGP network, and Tibet and Gansu are the key nodes in UHV network, and the participation or absence of which will have significant impact on the renewable hydrogen transmission system. Only minor adjustments to the transmission technical parameters of NGP or HGP can promote the qualitative overflight of the optimal transmission volume of them so as to achieve the target optimization at the minimum cost. • Optimal planning model framework for renewable hydrogen transmission is proposed. • The optimal transmission mode, network, and cost of renewable hydrogen are analyzed. • Thresholds and spatial features of the optimal plan vary with hydrogen supply level. • Renewable hydrogen will be transmitted inter-provincially at 5.4% of supply level. • Multiple equilibria for modes selection are observed by cost sensitivity analysis. [ABSTRACT FROM AUTHOR]

With the rapid increasing mileage of China's long-distance oil and gas pipelines, the intersection construction with other civil engineering, encroachment by invading the pipeline route, and other third-part problems occurred occasionally. Heavy vehicles rolling the serving pipeline have become one of the inevitable safety risks. The field test method of three in-service long oil and gas pipelines under heavy vehicle rolling is elaborated. The pipeline stress and soil pressure during tests are monitored and analyzed. The parametric model of pipe mechanical response under heavy vehicle rolling and stacking load is established, and the quantitative feedback of each parameter on pipeline stress safety response under heavy vehicle rolling is formed. The results show that the influence factors such as vehicle weight, vehicle speed, buried depth of pipeline, horizontal distance and cover plate on the stress state, vertical displacement state, and contact stress of pipe soil interface are highly consistent with the finite element method and test method, which could be a guideline for the safety assessment at rolling site. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The largest carbonate condensate field has been found in the Tarim Basin, NW China. Different from sandstone condensate gas reservoirs, however, the conventional gas injection for pressure maintenance development is not favorable for Ordovician fracture-cave reservoirs. Based on this, in this paper, 21 sets of displacement experiments in full-diameter cores and a pilot test in 11 boreholes were carried out to study enhanced oil recovery (EOR) in complicated carbonate reservoirs. The experimental results show that the seepage channels of the gas condensate reservoirs are fractures, which are quite different from sandstone pore-throat structures. Condensate oil recovery using water injection was up to 57–88% in unfilled fractured caves and at ca. 52–80% in sand-filled fractured caves. These values are much higher than the 14–46% and 17–58% values obtained from the depletion and gas injection experiments, respectively. The water injection in 11 wells showed that the condensate oil recovery increased by 0–17.7% (avg. 3.1%). The effective EOR for residual oil replacement using water injection may be attributed to fractures, as the gas channel leads to an ineffective gas circulation and pipe flow in fracture-cave reservoirs, which is favorable for waterflood development. The complicated fracture network in the deep subsurface may be the key element in the varied and lower oil recovery rates obtained from the wells than from the experiments. This case study provides new insights for the exploitation of similar condensate gas reservoirs. [ABSTRACT FROM AUTHOR]

With the improvement of natural gas network interconnection, the network topology becomes increasingly complex. The significance of analyzing topology is gradually becoming prominent, and a systematic analysis method is required. This paper selects two typical natural gas pipeline networks: one in Europe, and the other in North China. Based on complex network theory and the nature of natural gas pipelines, topological models for the two typical networks were established and the evaluation indexes were developed based on four factors: network type, overall topological structure characteristics, path-related topological structure characteristics, and topological structure robustness. Using these indexes, the topological structure of the two typical networks is compared and analyzed quantitatively. The comparison shows that the European network topology has more redundancy, higher transmission efficiency, and greater robustness. The topology analysis method proposed in this paper is practical and suitable for the preliminary analysis of natural gas pipeline networks. The conclusions achieved by this method can assist operators in gaining an intuitive understanding of the overall characteristics, robustness, and key features of pipeline network topology, which is useful in the implementation of hierarchical prevention and control. It also serves as a solid theoretical foundation and guidance for network expansion, interconnection construction, and precise hydraulic simulation calculation in the next stage. [ABSTRACT FROM AUTHOR]

A loess sinkhole is a typical geological hazard that is widely distributed in the Loess Plateau of China. However, some latent damages are difficult to detect in the natural hazard. Particularly, the serious damage caused by loess sinkholes is ever increasing, as the infrastructure rapidly developed in recent years. The resulting water and soil loss can aggravate and even trigger the occurrence, development of mudflows, collapses, and landslides. In addition, the sinkhole collapse can also seriously damage the farmland infrastructure, such as terraces, water storage facilities, and irrigation systems, as well as the infrastructures such as highways, railways, bridges, and oil and gas pipelines. Thus, it is a high demand to detect the loess sinkholes for the soil and water conservation and engineering construction in the loess regions. However, the traditional field surveys are costly and inefficient on the loess sinkholes. In this study, an automatic and object-oriented extraction of loess sinkholes was proposed to determine the influence of integrated terrain features on the extraction accuracy of the Convolutional Neural Networks (CNN) model. The study area was selected as Lanzhou City, Gansu Province in western China. The segmentation scale of the image was then determined by the Moran's I and Gray Level Co-occurrence Matrix entropy using WorldView 3 remote sensing image and ALOS digital elevation model data. An object-oriented extraction was implemented to obtain the spectrum (i.e., Mean_R, Mean_G, Mean_B, Std_R, Std_G, Std_B, Max_diff, and Brightness), shape (i.e., Area, Asymmetry, Border_index, Border_Length, Compactness, Density, Elliptic_Fit, Length/Width, Length, Shape_index, Roundness and Width), texture (i.e., GLCM_Homogeneity, GLCM_Contrast, GLCM_Mean, GLCM_Dissimilarity, GLCM_Entropy, and GLCM_Std), and terrain (i.e., Mean_DEM, Mean_Slope, Mean_Hillshade, Std_DEM, Std_Slope, and Std_Hillshade) features of the loess sinkholes. Two types of training samples were constructed with/without the terrain features, and then to train two CNN models for the extraction of the loess sinkholes in the same area. After that, the extraction accuracy of the model was evaluated, according to the precision rate, recall rate, and F1 score. A Support Vector Machine (SVM) model was also established to compare with the two CNN models. The research results show that the CNN model trained by integrating terrain features presented an accuracy rate of 94.62%, a recall rate of 86.27%, and an F1 score of 90.26%. Specifically, the false positive was significantly reduced, while the accuracy rate and F1 score increased by 18.10 percentage points, and 9.15 percentage points, respectively. The F1 scores of the two CNN models were both over 80%, which were 6.94 percentage points, and 16.09 percentage points higher than that of the SVM model, respectively. Consequently, the integrated terrain features to train the CNN model can effectively reduce the number of False Positive in the loess sinkholes, thus improving the comprehensive performance of the model. The extraction performances of the CNN models were all better than those of the SVM model. Therefore, the CNN model can be widely expected to integrate with the terrain features from the satellite data and object-oriented image analysis for the accurate and efficient extraction of the loess sinkholes. [ABSTRACT FROM AUTHOR]

A high-quality methane emission estimation in China's oil and gas sector is the basis of an effective mitigation strategy. Currently, the published emission data and studies of China's oil and gas sector only provide estimations of total emissions, which is not enough for good analysis of the trend and impact factors for the instruction of emission mitigation activities. The main problem is that published data for oil and gas infrastructure in China is incomplete, which makes it difficult to apply the conventional greenhouse gas inventory compiling method and the uncertainty estimation strategy. Therefore, this paper aims to develop a method to estimate infrastructure data using all available data, including partial data for the infrastructure, national production and consumption of oil and gas, and production and production capacity data of oil and gas enterprises, and then uses a Monte Carlo-based method to generate a source-based inventory and uncertainty analysis of methane emission for China's oil and gas industry from 1995 to 2018. We found that methane emission increased from 208.3 kt in 1995 to 1428.8 kt in 2018. Methane emission in 2018 has an uncertainty of about ±3%. Compared to former studies, our research found that the production stage of natural gas is the main contributor, which is further driven by the growth of natural gas production. The mitigation potential introduced by technology development on methane emission remains large. [ABSTRACT FROM AUTHOR]

The extensive use of natural gas provides a new approach to low carbonization of the structure of primary energy sources, as well as reduces the peak in carbon emissions before fossil fuels are completely replaced by clean energy. To explore the impact of the West–East Gas Pipeline Project (WEGPP) on energy conservation and emission reduction in Chinese inland areas, the effects of policy intervention on the socio-economic development in Hubei province are preliminary investigated in this paper. The causal inference of multi-bandwidth and multi-core analysis is carried out using regression discontinuity design (RDD), and the core conclusion of the counterfactual analysis is proven to be robust based on the synthetic control method. The results show that the transportation of natural gas from Western China to Hubei province can reduce the intensity of carbon emissions, demonstrating that it is an effective substitution to low-carbon energy. The WEGPP not only can meet the demands of a large number of energy shortages caused by the rise of the manufacturing industry, but also can solve the technique bottleneck of energy consumption in Central and Eastern China. The WEGPP has ensured the coordinated development in Western, Central, and Eastern China, achieving and maintaining a high and stable economic growth rate in China. These results have significant implications for making policies of energy conservation and emission reduction in a considerable number of gas-importing provinces in Central China. [ABSTRACT FROM AUTHOR]

With the rapid growth of the oil and gas storage, transportation, and pipeline industries, it is necessary to improve the construction process of oil and gas pipelines. By combining the technical advantages of horizontal directional drilling and pipe jacking construction, the direct pipe laying method is suitable for pipeline crossing in different strata in the oil and gas, water conservancy and hydropower, and municipal industries due to its advantages of less construction land, high speed, and reversibility. Using the rapid jacking and laying of pipelines crossing Nanjuma River in the 'Jingshihan' gas pipeline double line project as a case study, this paper investigates the application status of the direct pipe laying method, summarizes the project, and introduces the construction of the working well, equipment selection, guiding control technology, supporting equipment installation, and drag reduction measures, as well as analyzes the influencing factors of thrust force and trajectory deviation combined with formation information. [ABSTRACT FROM AUTHOR]

The construction of underground gas storage mostly focuses on depleted gas reservoirs. However, the depleted gas reservoir used to build underground gas storage in China is located far from the main gas consumption economic zone. It is necessary to reconstruct underground gas storage using nearby reservoirs in order to meet the needs of economic development. The complex three-phase seepage characteristics encountered in the process of reconstruction of underground gas storage reservoirs seriously affect their storage and injection production capacities. Combined with the mechanism of multiphase seepage and the multicycle injection production mode during the process of gas storage construction, the feasibility of rebuilding gas storage in medium- and low-permeability reservoirs was evaluated through relative permeability experiments and core injection production experiments. The results showed that the mutual driving of two-phase oil–water systems will affect the storage space and seepage capacity, that the adverse effect will be weakened after multiple cycles, and that increasing the gas injection cycle can enhance the gas-phase seepage capacity and improve the crude oil recovery. Therefore, we found that it is feasible to reconstruct underground gas storage in medium- and low-permeability reservoirs, which lays a foundation for the development of underground gas storage in China. [ABSTRACT FROM AUTHOR]

A prediction method applicable to erosion-prone areas of fluorine chemical pipelines is herein proposed. By summarizing the common working conditions in the fluorine chemical industry, a computational fluid dynamics (CFD) model for industrial pipelines is established, and three-dimensional numerical calculations of the flow field in the pipelines are carried out to analyze the characteristics of the hydrodynamic parameters and phase distribution in the flow field, as well as the erosion rate distribution in different areas of the pipelines. The areas in the pipeline that are susceptible to erosion are predicted based on the results. The method has universal applicability and has been applied in many large petrochemical companies. It achieves the function of predicting the areas of severe pipeline erosion in a scientifically sound manner. This paper also details the application of the method in a distillation oil and gas pipeline of a large oil and gas company in western China. [ABSTRACT FROM AUTHOR]