48 results on '"Xiaozhi Zhou"'
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2. A multicenter study to evaluate the analytical precision by pathologists using the Aperio GT 450 DX
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Thomas W. Bauer, Matthew G. Hanna, Kelly D. Smith, S. Joseph Sirintrapun, Meera R. Hameed, Deepti Reddi, Bernard S. Chang, Orly Ardon, Xiaozhi Zhou, Jenny V. Lewis, Shubham Dayal, Joseph Chiweshe, David Ferber, Aysegul Ergin Sutcu, and Michael White more...
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Aperio GT 450 DX ,Digital pathology ,Whole slide imaging ,Analytical precision ,Computer applications to medicine. Medical informatics ,R858-859.7 ,Pathology ,RB1-214 - Abstract
Background: Digital pathology systems (DPS) are emerging as capable technologies for clinical practice. Studies have analyzed pathologists' diagnostic concordance by comparing reviews of whole slide images (WSIs) to glass slides (e.g., accuracy). This observational study evaluated the reproducibility of pathologists' diagnostic reviews using the Aperio GT 450 DX under slightly different conditions (precision). Method: Diagnostic precision was tested in three conditions: intra-system (within systems), inter-system/site (between systems/sites), and intra- and inter-pathologist (within and between pathologists). A total of five study/reading pathologists (one pathologist each for intra-system, inter-system/site, and three for intra-pathologist/inter-pathologist analyses) were assigned to the respective sub-studies.A panel of 69 glass slides with 23 unique histological features was used to evaluate the WSI system's precision. Each glass slide was scanned to generate a unique WSI. From each WSI, the field of view (FOV) was generated (at least 2 FOVs/WSI), which included the selected features (1–3 features/FOV). Each pathologist reviewed the digital slides and identified which morphological features, if any, were present in each defined FOV. To minimize recall bias, an additional 12 wild card slides from different organ types were used for which FOVs were extracted. The pathologists also read these wild card slides FOVs; however, the corresponding feature identification was not included in the final data analysis. Results: Each measured endpoint met the pre-defined acceptance criteria of the lower bound of the 95% confidence interval (CI) overall agreement (OA) rate being ≥85% for each sub-study. The lower bound of the 95% CI for the intra-system OA rate was 95.8%; for inter-system analysis, it was 94.9%; for intra-pathologist analysis, 92.4%, whereas for inter-pathologist analyses, the lower bound of the 95% CI of the OA was 90.6%. Conclusion: The study results indicate that pathologists using the Aperio GT 450 DX WSI system can precisely identify histological features that may be required for accurately diagnosing anatomic pathology cases. more...
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- 2024
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3. Effects of microstructure on hydraulic fracturing and gas–water production in coal reservoirs: A case study of the Dahebian coalbed methane block in Western Guizhou, China
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Shiliang Zhu, Xiaozhi Zhou, Fuping Zhao, Jiaxin Wu, Sijie Han, Lingyun Zhao, Peiming Zhou, Jun Wang, and Zigang Yang
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Dahebian block ,gas–water production law ,hydraulic fractures spatial distribution ,microstructure ,Technology ,Science - Abstract
Abstract The development of coalbed methane (CBM) in China is susceptible to the influence of microstructure. Therefore, it is crucial to understand the extension laws of hydraulic fractures and engineering responses in coal reservoirs affected by microstructure development. Utilizing the Dahebian block in western Guizhou as the study area, this investigation examines the coal reservoir characteristics, fracturing, and drainage engineering analysis of the well DC1 group in the region. The aim is to discuss the spatial distribution characteristics of hydraulic fractures, geological controlling factors influenced by microstructure, and their corresponding engineering responses. The results indicate that, for coal reservoirs unaffected by microstructure, the extension laws of the fracture network in both longitudinal and planar directions are influenced by burial depth and the regional stress field. In the microstructural belt, tectonic stress dominates, causing changes in the ground stress field. Consequently, the hydraulic fracture network deviates from the direction of the maximum principal stress during the extension process. When a secondary fracture is nearby, the hydraulic fracture network extends towards the shortest path radial secondary fracture direction, leading to a rapid increase in fracture width per unit length until it intersects with the secondary fracture. Additionally, the presence of secondary joints near the microfault structure decreases fracturing pressure and results in a dense distribution of the fracture network. This promotes the formation of a complex fracture network, favorable for fracturing. The extension of the fracture network in complex structural development areas is influenced by the microfault structure between wells, which is reflected in the fracturing construction pressure and fluid output. This accounts for the significant variations in the early drainage performance of CBM wells. more...
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- 2024
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4. Coalbed methane reservoir properties assessment and 3D static modeling for sweet-spot prediction in Dahebian block, Liupanshui Coal field, Guizhou Province, southwestern China
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Debashish Mondal, Shuxun Sang, Sijie Han, Xiaozhi Zhou, Fuping Zhao, Jinchao Zhang, and Wei Gao
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Coalbed methane ,Reservoir properties ,3D static modeling ,Sweet-spot prediction ,Dahebian ,Liupanshui coal field ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
Guizhou Province has many multi-layer, thin-thick coal seams; however, complex geology, incomplete reservoir characterization, and sweet-spot selection technology prevent large-scale coalbed methane (CBM) development. This study evaluates the CBM reservoir properties within the Dahebian block using logging data, coal sample analysis, and well-testing data and develops a 3D static reservoir properties model to analyze their spatial and vertical propagation. A sweet spot evaluation model was established using a multi-level fuzzy method based on 9 parameters extracted from a 3D static reservoir properties model. The coal measure has 22 coal seams, and seams >2 m thick have 2 or 3 thin non-coal layers intercalated. Coal seams 1#, 7#, and 11# are thin to thick, deeply buried, widely distributed, and have high gas content and saturation. Undeformed and cataclastic coal predominates the coal seam 1# and 7#, whereas coal seam 11# is dominated by cataclastic and granulated coal. The southern and central parts of coal seam 7# and 11# have less tectonically deformed coal (TDC). Coal seams 1# and 7# have low permeability relative to seam 11# and are localized, while coal seams 11# have high permeability, are extensively distributed, and contain substantial gas concentrations. Comparative analysis of evaluation scores and CBM production statistics shows that high scores indicate sweet spots for CBM development. Sweet-spot potential was classified as high, medium, and low. Scattered sweet spots are found in single layers, while combined development (1# + 7#+11#) reveals a wider high-potential area in the south-central region. This area, featuring deep, thick coal seams, high permeability, gas saturation, reservoir pressure, and low TDC proportion, indicates significant development potential. This study validates CBM development statistics, identifies future development areas, and guides the development of geologically complex Guizhou CBM. more...
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- 2024
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5. Research progress and breakthrough directions of the key technical fields for large scale and efficient exploration and development of coalbed methane in Xinjiang
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Shuxun SANG, Ruiming LI, Shiqi LIU, Xiaozhi ZHOU, Bo WEI, Sijie HAN, Sijian ZHENG, Fansheng HUANG, Tong LIU, Yuejiang WANG, Shuguang YANG, Dapeng QIN, and Zixin ZHOU
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geological uniqueness ,genesis and accumulation model ,engineering deployment methods ,geological adaptation technology ,synergistic exploration and development ,xinjiang coalbed methane ,Geology ,QE1-996.5 ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The Xinjiang Uygur Autonomous Region has presented the expected resource conditions and work foundations for a large-scale coalbed methane (CBM) exploration and development, which shows that its CBM resources below the depth of 2000 m are 7.5 trillion m3, 450 CBM wells have been constructed, and the annual gas production has approached to 80 million m3. Xinjiang has put forward the goal of the annual CBM production of 2.5 billion m3 in 2025. Therefore, the large-scale and efficient development of CBM in Xinjiang has become an urgent and significant demand. In this paper, the main research progresses of Xinjiang CBM made in five key technical fields have been systematically summarized, including the CBM enrichment model and area optimization technology, the prediction and detection technology for sweet spot distribution, the technological strategy of the accelerated rolling development and rapid increase of reserves and productions, the geological adaptation technology system, and the cooperative exploration and development of CBM with coal, oil and gas. Then, the potential breakthrough directions have been analyzed and proposed. Research has shown that the coal reservoirs in Xinjiang show the unique geological characteristics of CBM, including widely developed multi-thick coal seams, low rank coal development, the frequent occurrence of steep coal seams, the significant deformation and structural control of coal bodies, complex hydrologic and outcrop conditions, and the gas-bearing and physical properties with three “low” (low gas content, methane concentration, and gas saturation) and five “high” (high gas intensity, porosity, stress change, reservoir pressure change, and permeability change). The Xinjiang CBM has multiple genetic types and enrichment models, including biogenic mechanism, thermogenic mechanism, and biogenic-thermogenic composite genetic mechanism, etc., and their corresponding enrichment models. Biogenic gas reservoirs or biogenic gas contribute widely. The distribution and occurrence patterns of CBM in Xinjiang show some significant differences between foreland basin and intermountain basin. Therefore, the first breakthrough direction is to innovate and form the scientific evaluation based on the principle of “two separation” (low-rank and middle- and high-rank; shallow and deep coal) and “two combination” (geological and engineering evaluation; multivariate data) and the precise target optimization technology based on “machine learning + three-dimensional geological modeling”. The sweet spot of deep CBM/CMG (coal measure gas) in Xinjiang is mainly the uplift of the depression in the basin, the depression of the uplift in the basin, and the slope around the basin margin. The potential well location is the structurally high position, and the potential reservoir is the fissure-developed primary structure coal seam or pore and fissure-developed coal bearing sand conglomerate reservoir. Then, the second breakthrough direction is the sweet spot prediction and exploration technology for deep CBM/CMG based on “new method of geophysics, rock physics and rock mechanics stratigraphy” and “new concept of geological and engineering sweet spot”. The basic principles of the accelerated rolling development are low-risk, short-cycle, high-efficiency, and multi-batch project deployment. The technical strategies of the rapid increase of CBM reserves and productions in the middle and shallow coal seams include the new well layout and construction in the new optimized block and the old well reconstruction for the increase of CBM production in the mature block. While this strategy for the deep coal seam is to give priority to deployment and development in the sweet spot in the deep but gentle slope in the large basin and the uplift in the basin. Then, the third breakthrough direction is the engineering deployment methods and technical strategies for the scientific accelerated rolling development, and efficient and rapid increase of the gas reserves and productions. The important progresses have been made in the engineering technologies of Xinjiang CBM, such as the differential optimization and deployment of the well type and pattern, the drilling and cementing with a low reservoir damage, the high reliability logging and well testing, the efficient staged fracturing with the multi-well types, and the drainage control with the low casing pressure and controlled pressure. The fourth breakthrough direction is to develop and construct a geological adaptability technology system for a large-scale and efficient exploration and development of CBM in Xinjiang. For the middle and shallow CBM and coal cooperative exploration and development, the gas extraction followed by coal mining, the co-extraction of CBM and coal, and the co-extraction of CBM and in-situ oil-rich coal should be conducted. For the deep CBM, oil, and gas cooperative exploration and development, the development of coal measure superimposed gas reservoir, the co-exploration and co-extraction of CBM and CMG, and the exploration and development of the whole petroleum system in coal-bearing sequence should be conducted. These cooperative exploration and development of deep CBM, oil, and gas is the fifth breakthrough direction, whose developments have been considered and explored. The results of this study are expected to provide the technical support and engineering decision reference for a large-scale and efficient exploration and development of CBM in Xinjiang. more...
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- 2024
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6. Characteristics of the Microfracture and Pore Structure of Middle- and High-Rank Coal and Their Implications for CBM Exploration and Development in Northern Guizhou
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Haiying Ren, Zhijun Guo, Honggao Xie, Sijie Han, Xiaozhi Zhou, Lingyun Zhao, Yuanlong Wei, and Wenci Qiu
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CBM development ,middle- and high-rank coal ,microfractures ,fractal characteristics ,fracture density ,Technology - Abstract
The microfracture and pore structure characteristics of coal reservoirs are crucial for coalbed methane (CBM) development. This study examines the evolution of pore and fracture structures at the microscopic level and their fractal characteristics, elucidating their impact on CBM development in the northern Guizhou coal reservoirs. The results indicate that the pores and fractures in the coal reservoirs are relatively well-developed, which facilitates the adsorption of CBM. The density of primary fractures ranges from 5.8 to 14.4 pcs/cm, while the density of secondary fractures ranges from 3.6 to 11.8 pcs/cm. As the metamorphic degree of coal increases, the density of primary fractures initially increases and then decreases, whereas the density of secondary fractures decreases with increasing metamorphic degree. With increasing vitrinite reflectance, the specific surface area and pore volume of the coal samples first decrease and then increase. The fractal dimension ranges from 2.3761 to 2.8361; as the vitrinite reflectance of the coal samples increases, the fractal dimension D1 decreases initially and then increases, while D2 decreases. In the northern Guizhou region, CBM is characterized by an enrichment model of “anticline dominance + fault-hydrogeological dual sealing” along with geological controlling factors of” burial depth controlling gas content and permeability + local fault controlling accumulation”. The research findings provide a theoretical basis for the occurrence and extraction of CBM in northern Guizhou. more...
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- 2024
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7. The Prediction of Coalbed Methane Layer in Multiple Coal Seam Groups Based on an Optimized XGBoost Model
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Weiguang Zhao, Shuxun Sang, Sijie Han, Deqiang Cheng, Xiaozhi Zhou, Zhijun Guo, Fuping Zhao, Jinchao Zhang, and Wei Gao
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tree-structured parzen estimator ,XGBoost ,multiple coal seam groups ,coalbed methane layer prediction ,geophysical logging ,Technology - Abstract
The prediction of the optimal coalbed methane (CBM) layer plays a significant role in the efficient development of CBM in multiple coal seam groups. In this article, the XGBoost model optimized by the tree-structured Parzen estimator (TPE) algorithm was established to automatically predict the optimal CBM layer in complex multi-coal seams of the Dahebian block in Guizhou Province, China. The research results indicate that the TPE XGBoost model has higher evaluation metrics than traditional machine learning models, with higher accuracy and generalization ability. The optimal coalbed methane layer predicted by the model for the Dacong 1–3 well is the 11th coal seam. In addition, the interpretation results of the model indicate that sonic (AC) and caliper logging (CAL) are relatively important in determining the optimal CBM layer. The favorable layers for coalbed methane development are distributed in coal seams with developed fractures and high gas content. The TPE-XGBoost model can help us objectively analyze the significance of different types of logging, quickly predict the optimal layer in complex multiple coal seam groups, and greatly reduce costs and subjective impact. It provides a new approach to predict the best CBM layer in multiple coal seam groups in the Guizhou Province in the southwest of China. more...
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- 2024
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8. Technology processes of enhancement of broken soft and low permeability coal reservoir and surface development of coalbed methane
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Shuxun SANG, Fansheng HUANG, Yansheng SHAN, Xiaozhi ZHOU, Shiqi LIU, Sijie HAN, Sijian ZHENG, Tong LIU, Ziliang WANG, and Fengbin WANG
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coalbed methane ,broken soft and low permeability coal reservoir ,formation enhancement technology ,surface development ,hydraulic fracturing ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Broken soft and low permeability (BSLP) coal reservoirs are widely distributed in China. However, due to its soft and broken structure and low permeability, the conventional vertical/horizontal well direct fracturing technology is not ideal for the enhancement of BSLP coal seams and the surface development of coalbed methane (CBM). The efficient development of CBM in BSLP coal reservoirs has been an important technical bottleneck restricting the large-scale development of CBM industry and the efficient treatment of coal mine gas control in China. Based on the systematic analysis of the characteristics of BSLP coal reservoirs and the problems existing in the surface development of CBM, the current technological progress in the enhancement of BSLP coal reservoirs and surface development of CBM were reviewed by taking horizontal well as the base well type and focusing on three different technical directions: indirect fracturing, stress relief and consolidation before fracturing. The CBM development technologies of indirect fracturing, including roof indirect fracturing, gangue indirect fracturing and hard coal stratification indirect fracturing were summarized. The stress release CBM development technologies using different stress release methods, such as hydraulic jet cavitation, gas dynamic cavitation, mechanical + hydraulic + induced instability coupling cavitation and hydraulic slit, were reviewed. Furthermore, the CBM development technology of first consolidation and then fracturing of BSLP coal reservoirs induced by microorganisms was also summarized. The exploration of indirect fracturing technology has accumulated a lot of engineering practice, and has achieved a good effect on enhancing the BSLP coal reservoirs in areas with suitable geological conditions. The exploration of new technology for enhancing BSLP coal reservoir represented by stress release has also made great progress, and has entered the stage of engineering tests and verification. According to the characteristics of BSLP coal reservoir and the new development principle, the horizontal well stress release technology has greater potential for reservoir reconstruction and better effect for CBM development. Based on the horizontal well stress release method, the development trend of BSLP coal reservoir enhancement and surface CBM development technology was forecasted in three aspects: expanding the stress release range, improving the development effect of CBM and achieving the co-production of coal and CBM. It is expected to provide reference for improving the stimulation effect of BSLP coal reservoir and increasing the production of CBM well in China. more...
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- 2024
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9. Influence of tectonic fractures on CO2 storage and enhanced CH4 recovery
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Ziliang WANG, Shuxun SANG, Xiaozhi ZHOU, Xudong LIU, and Shouren ZHANG
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co2−ecbm ,tectonic fractures ,ch4 recovery ,co2 breakthrough ,injection pressure ,Geology ,QE1-996.5 ,Mining engineering. Metallurgy ,TN1-997 - Abstract
In the process of CO2-ECBM, the tectonic fractures developed in the coal may become the preferential channels of gas-water seepage under the impact of injection pressure, and then influence the recovery of coalbed methane (CBM) and CO2 storage. Based on the theoretical analysis, the displacing profile of CO2-ECBM is established. A numerical model is constructed referring to the TS-634 field trial, and the influence of the tectonic fractures on CH4 recovery and CO2 storage is investigated. The CBM recovery and CO2 storage in the TS-634 trial are evaluated, the mechanism of the rapid breakthrough of CO2 is revealed, the enlightenment of the rapid breakthrough on the optimization of the injection-drainage process is dissected, and the proposals for the injection-drainage process in reservoirs with tectonic fractures are put forward. The results show that CO2 enriched zone, CH4-CO2 mixed zone, CH4 enriched zone, and water enriched zone can be formed among injection-production wells successively. With an injection, the zones affect the producers after their formation and evolution. The difficulty of water seepage determines the level of CH4 output inhibition and then controls the CBM recovery and CO2 storage. The producer along tectonic fracture can achieve an efficient recovery of CH4, but a high permeability often leads to apparent CO2 channeling which causes the loss of cumulative CH4 production and CO2 storage. During the trial period, the strong-breakthrough producer attains a remarkable increase in gas output, with the actual cumulative gas production increasing by 10.4% and bottomhole-pressure-equivalent cumulative gas output increasing by 92.3%. Tectonic fractures provide potential preferential channels for the CO2 rapid breakthrough and become real preferential channels mainly induced by injection pressure. The existence of fracturing affected areas and liquid CO2 phase transformation-induced expansion and energization accelerate the CO2 breakthrough, but the coal matrix expansion-induced permeability decrease is expected to delay the breakthrough. To achieve a better displacement, enhancement, and sequestration, it is necessary to boost the bottomhole pressure in the early injection stage, fine-tune the pressure of the injector or increase the bottomhole pressure drop of producers in the inhibition stage, and maintain the pressure lower than the minimum principal stress of the reservoir in the whole stage. After the breakthrough, the exposure time between CO2 and coal matrix can be increased by irregularly shutting down/restarting the producers or reducing the pressure of the injector, which is expected to further improve the CH4 recovery. more...
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- 2023
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10. Research progress on technical basis of synergy between CO2 geological storage potential and energy resources
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Shuxun SANG, Shiqi LIU, Qianlin ZHU, Sijie HAN, Shouren ZHANG, Kelong TAN, Xiaozhi ZHOU, Sijian ZHENG, Xu WANG, and Tong LIU
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co2 geological storage potential ,energy resource system ,carbon capture, utilization and storage ,source-sink matching ,synergistic relationship ,cluster deployment ,Geology ,QE1-996.5 ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Large-scale cluster deployment is the development direction of the CCUS (Carbon Capture, Utilization and Storage) technology and the national major demand of fossil energy low-carbon utilization. The synergistic relationship and mechanism between CO2 geological storage potential and energy resources are the theoretical basis of the CCUS large-scale cluster deployment. In this study, the major progress in the fields of CO2 geological storage potential and its evaluation methods, the CCUS source-sink matching and pipe network design model, the synergistic relationship between CO2 geological storage potential and energy resources, and the technical basis and mode of the CCUS cluster deployment are systematically reviewed. The research ideas on the theoretical methodology of synergy between CO2 geological storage potential and energy resources in China are discussed and envisioned. The main conclusions of the research are as follows. The CO2 geological storage potential restricts the development potential and application scale of the CCUS technology. The evaluation method system of CO2 geological storage potential is preliminarily established, which is composed of suitability evaluation method, storage capacity evaluation method, and storage site selection method. However, the evaluation method system of CO2 geological storage potential urgently needs to be improved and developed in future research. Source-sink matching is the important direct basis for the CO2 transportation pipeline network design and the CCUS large-scale cluster deployment. The improvement and establishment of the optimization model between the CCUS source-sink matching and the CCUS cluster pipe network model is the key technology for the CCUS source-sink matching, and the transformation from single-stage static planning model to multi-stage dynamic planning model is the development direction. The synergy between CO2 geological storage potential and energy resources constitutes the constraint condition of the CCUS technology. The synergy between the CCUS technology and new energy technology, e.g., renewable energy, hydrogen energy, energy storage, etc. will be expected to form a new path, new mode, and new direction to achieve energy system decarbonization. The synergistic relationships between CO2 geological storage potential and biomass and water resources restrict the large-scale deployment area of the CCUS technology and the application potential of the BECCS (Bioenergy with Carbon Capture and Storage) technology. Therefore, the research on the optimization model of energy and resources system based on the CCUS source-sink matching model will be a new technical requirement. The CO2 geological storage potential, energy-system constrained CCUS source-sink matching optimization scheme, and full flowsheet CCUS technology constitute the key technical basis for the CCUS cluster deployment. The CCUS cluster deployment mode of onshore storage with near-source transportation should be the priority development direction in China. The CCUS cluster deployment mode of onshore storage and offshore storage with remote-source transmission also have development prospects in Yangtze River Delta and Great Bay Area. more...
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- 2023
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11. Numerical simulation of CO2-ECBM based on 3D heterogeneous geological model
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Xudong LIU, Shuxun SANG, Xiaozhi ZHOU, Shiqi LIU, Sijie HAN, Ziliang WANG, Shouren ZHANG, Jian WU, and Bing ZHANG
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co2 geological sequestration-enhanced coalbed methane ,3d heterogeneous geological model ,coalbed methane stimulation ,co2 sequestration ,injection process optimization ,Geology ,QE1-996.5 ,Mining engineering. Metallurgy ,TN1-997 - Abstract
CO2 geological sequestration-enhanced coalbed methane (CO2-ECBM) strengthens the development of coalbed methane (CBM) and realizes the stimulation of coalbed methane wells. At the same time, CO2 is stored in deep coal seams. This technology has some great development prospects. Relying on the demonstration project, numerical simulation based on geological modeling is still an important path for its technological development. Based on the analysis of the characteristics for the corner grid geological model and the geological modeling ability of COMSOL Multiphysics, a geological model that can clearly display the three-dimensional spatial morphology and heterogeneity distribution of gas content, adsorption time, porosity, permeability, elastic modulus and Poisson’s ratio of the No. 3 coal in the Shizhuang South Block of Qinshui Basin was established in COMSOL Multiphysics using the split-reconstruction method. On this basis, the numerical simulation of CO2-ECBM for controlling gas injection pressure was carried out in combination with the adsorption-hydraulic-thermal-mechanical-chemical (AHTMC) multi-field coupling mathematical model, and the impact of CO2 injection pressure on CH4 stimulation, CO2 storage and the geochemical environment of coal reservoir were analyzed. Moreover, two kinds of shut-in modes, namely, simultaneous shut-in and sequential shut-in, and four CO2-ECBM engineering objectives, namely, time saving, CH4 stimulation, CO2 storage and comprehensive consideration of the three, were proposed. In addition, the CO2 injection pressures were optimized according to the two shut-in modes with the four objectives. The results show that: ① Under the limit of 15-year and the injection pressure of 5.50−9.50 MPa for the CO2-ECBM project, with the increase of CO2 injection pressure, the CH4 production rate of CBM wells and the CO2 storage capacity of coal reservoir increase, with the maximum of 14.39% and 8.31×107 m3 respectively, the area of coal reservoir containing acid fissure water expands. The CO2 storage rate decreases due to the large output of CO2 from CBM wells with the increase of gas injection pressure, but remains above 95%. ② The heterogeneity of coal reservoirs has a great impact on the production of CBM wells. The higher the CH4 content and the greater the porosity and permeability of the coal reservoirs around the CBM wells, the more significant the CH4 stimulation effect. The stronger the CO2 adsorption capacity of the coal reservoirs surrounding CBM wells, the lower their CO2 production rate. ③ Under the simultaneous and sequential shut-in, CO2 injection pressure has a significant impact on the CO2 concentration and CH4 production rate of gas produced by well group, and the CH4 recovery of coal reservoir decreases with the increase of injection pressure at the end of CO2-ECBM project with 33.28% and 41.63% for 3.50 MPa, 18.90% and 28.03% for 6.50 MPa and 12.81% and 23.01% for 9.50 MPa, respectively. ④ The optimal injection pressure of CO2 for the engineering objectives of time saving, CH4 stimulation, CO2 storage and comprehensive consideration of above three are 8.05, 3.50, 6.35 and 6.25 MPa for the simultaneous shut-in, respectively, and 9.50, 9.50, 3.50 and 9.50 MPa for the sequential shut-in, respectively. ⑤ Compared with simultaneous shut-in, the sequential shut-in can achieve better CH4 stimulation and CO2 storage effects by extending the engineering time when using the optimal CO2 injection pressure. more...
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- 2023
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12. Impact of salinity of fracturing fluid on the migration of coal fines in propped fractures and cleats
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Fansheng HUANG, Shuxun SANG, Shiqi LIU, Qiang CHEN, Xiaozhi ZHOU, and Meng WANG
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coal fines migration ,fracturing fluid ,critical salt concentration ,propped fracture ,cleat ,Geology ,QE1-996.5 ,Mining engineering. Metallurgy ,TN1-997 - Abstract
During the hydraulic fracturing of coalbed methane (CBM) well, the deposition of coal fines in propped fractures and the migration of coal fines in cleats will damage the permeabilities of propped fractures and cleats, consequently affecting the hydraulic fracturing and the subsequent drainage of CBM well. For the purpose of dredging propped fractures and avoiding the clogging of cleats effectively, a novel method for the control of coal fines in propped fractures and cleats during hydraulic fracturing was proposed by optimizing the salinity of fracturing fluid. With the salinity decreasing stepwise, the experiments on the migration of coal fines in propped fractures and cleats were conducted on quartz sand-packed columns and anthracite coal plugs, respectively, to investigate the response characteristics of the migration of coal fines to the change of salinity. Additionally, the migration of coal fines was simulated by using the extended DLVO method, to elucidate the influence mechanisms of salinity on the migration of coal fines. On this basis, the optimal salinity range that takes into account the control of coal fines in propped fractures and cleats was explored. The results indicated that there existed a critical salt concentration (CSC) for the migration of coal fines in both propped fractures and cleats. When the salinity was lower than the CSC, the permeability of propped fractures abruptly increased while that of cleats decreased sharply, accompanied by a large amount of coal fines produced. The value of the CSC for the migration of coal fines in propped fractures was higher than that in cleats, which can be attributed to the fact that the surface electronegativity of proppants was stronger than that of cleats, while the hydrophobicity was weaker than that of cleats. With the gradual decrease of salinity, the electric double layer (EDL) repulsive force between coal fines and channel increased continuously. When the salinity decreased to the CSC, the EDL repulsion started to be greater than the sum of Lifshitz-van der Waals attraction and Lewis acid-base attraction, resulting in the migration of coal fines. Both the values of the predicted CSCs for the migration of coal fines in propped fractures and cleats were consistent with experimental data, indicating the effectiveness of the model. During hydraulic fracturing, the salinity of fracturing fluid can be designed between the CSCs for the migration of coal fines in propped fractures and cleats. In that case, the production of coal fines in propped fractures is promoted while the migration of coal fines is inhibited in cleats, so as to achieve the dual purposes of coal fines control in propped fractures and cleats. more...
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- 2023
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13. Investigation on the influence of the macropores in coal on CBM recovery
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Xudong Liu, Shuxun Sang, Xiaozhi Zhou, Shiqi Liu, Ziliang Wang, and Youxin Mo
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Coalbed methane ,Pore connectivity ,Permeability ,Full coupling ,Numerical simulation ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
As an important component of coal structure, the macropores have a great influence on CBM recovery. In this paper, the macropores characteristic of two coal samples collected from 3# coal seam in the south of Qinshui Basin, China was analyzed on the basic of mercury intrusion porosimetry, and a fully coupled triple-porosity/double permeability mathematical model for CBM recovery was established according to the physical structure of coal and the non-Darcy flow of methane in macropores. Then, the various factors affecting the macropores permeability were discussed and the influence of size distribution and connectivity of macropores on CBM recovery was investigated. The following conclusions have been drawn from these efforts: (1) in 3# coal seam of the south of Qinshui Basin, the macropores have an extremely heterogeneous pore size distribution with the high variation, and their connectivity is not good because they are mainly composed of the conical and cylindrical pores with one dead end and the open pores, the structure characteristics of macropores are not conducive to CBM recovery; (2) the fully coupled triple-porosity/double permeability mathematical model containing the non-Darcy flow of methane in the macropores includes the methane occurrence-migration field, hydraulic field, thermal field and stress field as well as the complex intercoupling between them, and the model was verified by the fitting of methane production history, with an average error of 3.24%; (3) the macropores permeability is closely related to the Knudsen number controlled by methane pressure and temperature in macropores and the intrinsic permeability which is an internal attribute of macropores affected by size distribution and connectivity of pore; (4) the pressure drop of reservoir plays a major role in the macropores permeability, which promotes the increase of macropores permeability with time, and the high intrinsic permeability of macropores corresponding to the good pore size distribution and connectivity is more conducive to the improvement of fracture permeability and methane production rate of coal reservoir during CBM recovery. It is recommended that coal seams including the macropores with uniform size distribution and good connectivity should be preferentially used for the development of CBM. more...
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- 2023
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14. Paleotectonic Stress and Present Geostress Fields and Their Implications for Coalbed Methane Exploitation: A Case Study from Dahebian Block, Liupanshui Coalfield, Guizhou, China
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Jilin Wang, Youkun Wang, Xiaozhi Zhou, Wenxin Xiang, and Changran Chen
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joint ,natural fractures ,tectonic stress field ,geostress ,coalbed methane ,Technology - Abstract
The macroscopic structural fractures (joints) and geostress distribution characteristics of coal reservoirs are important factors affecting the exploitation of coalbed methane (CBM). In this study, the joints in the sedimentary strata of the Dahebian block in Liupanshui area, Guizhou Province were investigated. Directional coal samples were collected for observation and statistical analysis of coal microfractures, the paleotectonic stress fields of the study area were reconstructed, and the tectonic evolution was elucidated. The geostress distribution characteristics of the target coal seam (coal seam No. 11, P3l) in the study area were analyzed using the finite element numerical simulation method. The results indicate that the structural evolution of the Dahebian syncline in the study area can be divided into two stages. The Late Jurassic–Early Cretaceous stage (Early Yanshanian) is the first stage. Affected by the sinistral strike slip of the Weining–Ziyun–Luodian (WZL) fault zone, the derived stress field in the study area exhibits maximum principal stress (σ1) in the NEE–SWW direction. The Late Cretaceous stage (Late Yanshanian) is the second stage. Affected by the dextral strike slip of the WZL fault zone, the derived stress field exhibits σ1 in the NNW–SSE direction. The folds and faults formed in the first stage were modified by the structural deformation in the second stage. The dominant strikes of joints in the sedimentary strata are found to be in the NW–NNW (300°–360°) and NE (30°–60°) directions, with dip angles mostly ranging from 60° to 90°. The dominant strikes of coal microfractures are in the NW (285°–304°) and NE (43°–53°) directions. The distribution of geostress in the study area is characterized by high levels of geostress in the syncline center, decreasing towards the surrounding periphery. The overall trend of the geostress contour line is similar to the shape of the syncline and is influenced by folds and faults. The σ1 of coal seam No. 11 is vertical stress. The prediction results show that the joint density of coal seam No. 11 in the block is 36–50 joints/m, and the shape of the joint density contour line is also affected by the axial direction of the Dahebian syncline and the surrounding faults. The variation in coal seam joint density and the control effect of geostress on joints opening or closing affects the permeability of coal reservoirs. The study results provide significant guidance for the exploitation of CBM. more...
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- 2023
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15. Relationship between the Geological Origins of Pore-Fracture and Methane Adsorption Behaviors in High-Rank Coal
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Sijie Han, Xiaozhi Zhou, Jinchao Zhang, Wenxin Xiang, and Ang Xu
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Chemistry ,QD1-999 - Published
- 2022
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16. Mineral and Metabolome Analyses Provide Insights into the Cork Spot Disorder on ‘Akizuki’ Pear Fruit
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Yingjie Yang, Yanlin Zhu, Piyu Ji, Anqi Li, Zhiyun Qiu, Yuanyuan Cheng, Ran Wang, Chunhui Ma, Jiankun Song, Zhenhua Cui, Jianlong Liu, Yitian Nie, Xiaozhi Zhou, and Dingli Li
- Subjects
minerals ,metabolites ,cork spot disorder ,Akizuki ,pear ,Plant culture ,SB1-1110 - Abstract
Cork spot is a common physiological disorder in pear fruits, which has been found in some pear cultivars. Mineral nutrition imbalance in fruit is regarded as the principal influence factor for disorder incidence, with some ongoing confusion and controversy. In our research, we explored the cork spot characteristics in Japanese pear ‘Akizuki’ (Pyrus pyrifolia Nakai), adopted metabolome and mineral content analysis for healthy and disordered fruits, and made a correlation analysis of mineral and metabolites. Cork spots are mainly distributed on the outer flesh beneath the fruit peel. In cork spotted tissues, superoxide (SOD) and peroxidase (POD) activities, as well as malondialdehyde (MDA) content, increased. A total of 1024 known metabolites were identified from all the samples and more changes in metabolism were detected between normal and cork spotted flesh tissues. Correlation analysis displayed that Ca, especially the Mg/Ca in fruits, could be used to predict whether an orchard will develop cork spot disorder; Mg and B were associated with the appearance of symptoms, and the contents of Zn, Fe, and Mg, as well as Mg/B and Zn/B, might be strongly tied to the formation of cork spots in pears. This research provides insights into the occurrence of pear cork spot disorder and clarifies the role of minerals. more...
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- 2023
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17. Evaluation of closed gob methane sweet spots: A case study of the Tiefa mining area
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Bo Wang, Huazhou Huang, Shuxun Sang, Xiaozhi Zhou, Zhichao Jia, and Huajun Zhang
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closed gob methane ,combined weight ,comprehensive evaluation ,resource assessment ,sweet spots ,Technology ,Science - Abstract
Abstract The coal seam gas development in closed gob zone is still in the exploratory stage in China, and potential evaluation and sweet spots selection are the key issues. This paper establishes a complete evaluation system for selecting sweet spots for closed gob methane extraction with surface wells in the Tiefa mining area to reduce the blindness of area selection. The one‐vote veto system, the comprehensive evaluation index system, and the AHP‐entropy combined weight model are used to screen and evaluate the closed gob zones in the Tiefa mining area. A total of twenty evaluation units are evaluated and the development potential of which is classified as three levels by the optimal segmentation method. The relationship between the results of the assessment and the closed gob methane resource is also discussed, as well as the combined weight distribution coefficient. The results show that the development potential of the block cannot be estimated simply by the closed gob methane resource because the consistency between the comprehensive evaluation value and the closed gob methane resource is poor. The size of the combined weight distribution coefficient has little effect on the comprehensive evaluation values and only affects the ranking of evaluation units in a small range. more...
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- 2020
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18. Experimental Study on the Influence of Effective Stress on the Adsorption–Desorption Behavior of Tectonically Deformed Coal Compared with Primary Undeformed Coal in Huainan Coalfield, China
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Kun Zhang, Shuxun Sang, Mengya Ma, Xiaozhi Zhou, and Changjiang Liu
- Subjects
tectonically deformed coal ,effective stress ,adsorption–desorption behavior ,strain response ,Technology - Abstract
In order to explore the influences of effective stress change on gas adsorption–desorption behaviors, primary undeformed coal (PUC) and tectonically deformed coal (TDC) from the same coal seam were used for adsorption–desorption experiments under different effective stress conditions. Experimental results showed that gas adsorption and desorption behaviors were controlled by the coal core structure and the pore-fissure connectivity under effective stress. The coal matrixes and fissures were compressed together under effective stress to reduce connectivity, and it was difficult for gas to absorb and desorb as the stress increased in primary undeformed coal. The loose structure of tectonically deformed coal cores can help gas to fully contact with the coal matrix, resulting in higher adsorption gas volumes. The support of coal particles in tectonically deformed coal cores weakens the compression of intergranular pores when effective stress increases, which in this study manifested in the fact that while the volumetric strain of the coal matrix change rapidly under low effective stress, but the adsorbed gas volume did not decrease significantly. The reduction in effective stress induced the rapid elastic recovery of the coal matrix and the expansion of cracks, and increased desorption gas volumes. The stress reduction significantly increased the initial gas volume of the tectonically deformed coal, while promoting slow and continuous gas desorption in primary undeformed coal. Therefore, the promotion effect of the reservoir pressure reduction on gas desorption and coal connectivity enhancement can help to improve coalbed methane recovery in primary undeformed coal and tectonically deformed coal reservoirs. more...
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- 2022
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19. Evaluation of coal and shale reservoir in Permian coal-bearing strata for development potential: A case study from well LC-1# in the northern Guizhou, China
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Hongjie Xu, Shuxun Sang, Jingfen Yang, Jun Jin, Huihu Liu, Xiaozhi Zhou, and Wei Gao
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Production of electric energy or power. Powerplants. Central stations ,TK1001-1841 ,Renewable energy sources ,TJ807-830 - Abstract
Indentifying reservoir characteristics of coals and their associated shales is very important in understanding the co-exploration and co-production potential of unconventional gases in Guizhou, China. Accordingly, comprehensive experimental results of 12 core samples from well LC-1# in the northern Guizhou were used and analyzed in this paper to better understand their vertical reservoir study. Coal and coal measured shale, in Longtan Formation, are rich in organic matter, with postmature stage of approximately 3.5% and shales of type III kerogen with dry gas generation. All-scale pore size analysis indicates that the pore size distribution of coal and shale pores is mainly less than 20 nm and 100 nm, respectively. Pore volume and area of coal samples influenced total gas content as well as desorbed gas and lost gas content. Obvious relationships were observed between residual gas and BET specific surface area and BJH total pore volume (determined by nitrogen adsorption). For shale, it is especially clear that the desorbed gas content is negatively correlated with BET specific surface area, BJH total pore volume and clay minerals. However, the relationships between desorbed gas and TOC (total organic carbon) as well as siderite are all well positive. The coals and shales were shown to have similar anoxic conditions with terrestrial organic input, which is beneficial to development of potential source rocks for gas. However, it may be better to use a low gas potential assessment for shales in coal-bearing formation because of their low S 1 +S 2 values and high thermal evolution. Nevertheless, the coalbed methane content is at least 10 times greater than the shale gas content with low desorbed gases, indicating that the main development unconventional natural gas should be coalbed methane, or mainly coalbed methane with supplemented shale gas. more...
- Published
- 2019
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20. Characteristics of middle-high-rank coal reservoirs and prospects for CBM exploration and development in western Guizhou, China.
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Fuping Zhao, Sijie Han, Haiying Ren, Xiaozhi Zhou, Jinchao Zhang, Wenxin Xiang, Zhijun Guo, and Yongyu Yang
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- 2024
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21. Coal Body Structure Detection Based on Logging and Seismic Data and Its Impacts on Coalbed Methane Development: A Case Study in the Dahebian Block, Western Guizhou, Southern China
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Yong Shu, Shuxun Sang, Xiaozhi Zhou, and Fuping Zhao
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General Environmental Science - Published
- 2023
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22. Permeability Response Characteristics of Primary Undeformed Coal and Tectonically Deformed Coal under Loading–Unloading Conditions in Huainan Coalfield, China
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Kun Zhang, Shuxun Sang, Mengya Ma, Xiaozhi Zhou, Changjiang Liu, and Guodong Shen
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General Chemical Engineering ,General Chemistry - Abstract
Reservoir pressure relief is a practical method to enhance permeability for coalbed methane (CBM) extraction in tectonically deformed coal (TDC) reservoirs. To explore the coal permeability response to stress changes, the primary undeformed coal (PUC) and TDC from the same coal seam were sampled for the pore-fissure structure analysis, mechanical property test, and permeability experiments under different stress loading-unloading methods in this study. The experimental results demonstrated that the coal permeability is more sensitive to the changes in confining pressure (perpendicular to airflow) than axial stress (parallel to airflow). Coal permeability decreases negatively exponentially as the confining pressure increases, and its change process with increased axial pressure can be divided into five stages in this study. The pore structures and mechanical properties of coal samples affected their permeability response to stress changes. Under the stress loading condition, the coal matrix and fractures of PUC samples were compressed simultaneously, and the permeability was regulated by the pore-fissure structures in the coal matrix. Due to the deformation and displacement of coal particles, the permeability of the TDC sample is predominantly dependent on changes in intergranular pores. At the initial stress unloading stage, the fissure recovery and expansion lead to a rapid increase in permeability, but the permeability cannot rereach the original value when the stress is fully released. Furthermore, the influencing factors of coal permeability in response to stress loading-unloading also include confining pressure conditions and coal matrix adsorption swelling. Research on the permeability response characteristics of the stress loading-unloading process can provide some clarifications for the reservoir depressurization and permeability enhancement of CBM extraction in the TDC reservoir. more...
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- 2022
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23. Similar Material Proportioning and Preparation of Ductile Surrounding Rocks for Simulating In Situ Coalbed methane Production from Tectonically Deformed Coals
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Xuwei Hou, Xiaozhi Zhou, and Jienan Pan
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Geology ,Geotechnical Engineering and Engineering Geology ,Civil and Structural Engineering - Published
- 2022
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24. Re-Evaluating the Accurate Multiphase Water Distribution in Coals: Unifying Experiment and Theory
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Sijian Zheng, Yanbin Yao, Dameng Liu, Shuxun Sang, Shiqi Liu, Meng Wang, Xiaozhi Zhou, Ran Wang, Sijie Han, and Tong Liu
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General Chemical Engineering ,Environmental Chemistry ,General Chemistry ,Industrial and Manufacturing Engineering - Published
- 2023
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25. Response in coal reservoirs and in-situ stress control during horizontal well coal cavern completion and stress release
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Ziliang Wang, Shuxun Sang, Xiaozhi Zhou, Shiqi Liu, He Wang, and Yong Shu
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- 2023
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26. Modelling of geomechanical response for coal and ground induced by CO2-ECBM recovery
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Xudong Liu, Shuxun Sang, Xiaozhi Zhou, Ziliang Wang, Qinghe Niu, and Debashish Mondal
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- 2023
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27. Changes of Multiscale Surface Morphology and Pore Structure of Mudstone Associated with Supercritical CO2-Water Exposure at Different Times
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Fayi Liu, Xiaozhi Zhou, Wei Wang, Qinghe Niu, Chang Jiangfang, Kun Zhang, and Shuxun Sang
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Morphology (linguistics) ,Materials science ,Coalbed methane ,020209 energy ,General Chemical Engineering ,Energy Engineering and Power Technology ,02 engineering and technology ,Supercritical fluid ,Fuel Technology ,020401 chemical engineering ,Chemical engineering ,Reservoir water ,0202 electrical engineering, electronic engineering, information engineering ,0204 chemical engineering - Abstract
CO2 enhanced coalbed methane recovery (CO2-ECBM) has been confirmed as an effective technology to improve coalbed methane (CBM) production; however, the injected CO2 and the reservoir water can rea... more...
- Published
- 2021
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28. Coupled adsorption-hydro-thermo-mechanical-chemical modeling for CO2 sequestration and well production during CO2-ECBM
- Author
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Xudong Liu, Shuxun Sang, Xiaozhi Zhou, and Ziliang Wang
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General Energy ,Mechanical Engineering ,Building and Construction ,Electrical and Electronic Engineering ,Pollution ,Industrial and Manufacturing Engineering ,Civil and Structural Engineering - Published
- 2023
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29. Experimental study the influences of geochemical reaction on coal structure during the CO2 geological storage in deep coal seam
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Shuxun Sang, Changjiang Liu, Kun Zhang, Mengya Ma, and Xiaozhi Zhou
- Subjects
Bituminous coal ,business.industry ,020209 energy ,geology.rock_type ,Anthracite ,Coal mining ,geology ,Geochemistry ,Carbonate minerals ,02 engineering and technology ,Geotechnical Engineering and Engineering Geology ,Feldspar ,chemistry.chemical_compound ,Fuel Technology ,020401 chemical engineering ,chemistry ,visual_art ,Silicate minerals ,0202 electrical engineering, electronic engineering, information engineering ,visual_art.visual_art_medium ,Coal ,0204 chemical engineering ,business ,Chlorite - Abstract
Deep unminable coal seams are suitable geological bodies for carbon dioxide capture and storage (CCS). In order to discuss the geochemical reaction between the injected carbon dioxide (CO2) and deep coal seam, and study its influence on the structure of reservoir, the high-ash anthracite, high-volatile anthracite, low-volatile bituminous coal obtained from Qinshui basin, China, and high-volatile bituminous coal obtained from Bohaiwan basin, China, were processed to 4–8 mm. Then the simulation experiments for the CO2 injection were conducted for 10 days at the burial depth of 1500 m under in-situ reservoir conditions. The conclusions were obtained based on the changes of minerals, elemental concentrations and pore structure parameters of coal before and after the reaction. Different minerals underwent various geochemical reactions and mechanisms after CO2 injection. These geochemical reactions can transform the reservoir structure, which was mainly reflected in the connection of pores and fissures, and the blockage on the pore throat. The reactions between carbonate minerals and the CO2 acid fluid were violent and quick, which can increase the volume of macropores and fractures. While the weak reactions of silicate minerals may affects the micropores in coal. The chlorite and feldspar could continuously react with the CO2 acid fluid, with the slow dissolution of potassium, sodium and silicon, which makes it possible to use these characteristics to monitor the geochemical reaction. Besides, the volumes of the micropores (1–2 nm) in the anthracite were significantly increased, making it a potential geological body for CCS. more...
- Published
- 2019
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30. Numerical study on CO2 sequestration in low-permeability coal reservoirs to enhance CH4 recovery: Gas driving water and staged inhibition on CH4 output
- Author
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Ziliang Wang, Shuxun Sang, Xiaozhi Zhou, and Xudong Liu
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Fuel Technology ,Geotechnical Engineering and Engineering Geology - Published
- 2022
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31. Cyclic Response of Loose Anisotropically Consolidated Calcareous Sand under Progressive Wave–Induced Elliptical Stress Paths
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Xiaozhi Zhou, Armin W. Stuedlein, Zhe Zhang, Hanlong Liu, and Yumin Chen
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Stress (mechanics) ,Progressive wave ,Principal stress rotation ,Liquefaction ,Geotechnical engineering ,Cyclic response ,Geotechnical Engineering and Engineering Geology ,Calcareous ,Geology ,Seabed ,General Environmental Science - Abstract
Observations of the performance of coastal and marine structures in weather events that produce standing and/or progressive waves have pointed to liquefaction of the seabed as a contributin...
- Published
- 2020
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32. Experimental study of permeability changes and its influencing factors with CO2 injection in coal
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Shiqi Liu, Xiaozhi Zhou, Shuxun Sang, Liwen Cao, and Qinghe Niu
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Materials science ,020209 energy ,Effective stress ,Energy Engineering and Power Technology ,Soil science ,02 engineering and technology ,complex mixtures ,Adsorption ,020401 chemical engineering ,otorhinolaryngologic diseases ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Coal ,0204 chemical engineering ,Moisture ,business.industry ,technology, industry, and agriculture ,Coal mining ,Geotechnical Engineering and Engineering Geology ,Supercritical fluid ,respiratory tract diseases ,Permeability (earth sciences) ,Fuel Technology ,Swelling ,medicine.symptom ,business - Abstract
Injecting CO2 into coal seams is a significant CO2 utilization approach when considering the dual environmental and energy benefits. However, the interaction of the coal matrix with CO2 is closely related to the permeability of a coal reservoir, which is simultaneously influenced by various factors, e.g., the moisture, temperature, coal rank and effective stress. To investigate the impact mechanism and the contribution of each influencing factor for the reservoir permeability and provide helps for the implementation schemes during the geological CO2 sequestration, a series of corresponding permeability tests were conducted under different adsorption pressures (2–10 MPa), moisture states (dry and wet), temperatures (35–65 °C), coal ranks (Ro,max = 0.68%–3.33%), effective stresses (3–10 MPa). The results show that coal matrix swelling induced by CO2 adsorption narrows the cleat width and reduces the permeability of a coal reservoir, which phenomenon is more serious for supercritical CO2. Injecting CO2 into the wet coal causes a higher PALR than the dry coal, which can be owned to the synthesized influences of the CO2 adsorption swelling, moisture-induced swelling and water blocking effect. The temperature first reduces the permeability of CO2 bearing coal incipiently by the swelling strains (thermal swelling and CO2 adsorption swelling) and then alleviates the permeability loss due to the remarkable gas slippage effect. Although the medium rank coal possesses the highest PALR, its permeability is also larger than the low rank coal and the high rank coal after CO2 adsorption. A cyclic loading and unloading leads to an irreversible permeability loss of a coal, which is more obviously reflected on the CO2 bearing coals. The analysis of the permeability contribution ratio indicates that the coal rank, CO2 adsorption and effective stress variety are the main controlling factors for the reservoir permeability, followed by the moisture, and the influence of the temperature on the permeability drop is quite weak. In summary, taking into account the various influencing factors and optimizing the injection arrangement are conducive to the successful implementation of the geological CO2 sequestration. more...
- Published
- 2019
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33. Anisotropic Adsorption Swelling and Permeability Characteristics with Injecting CO2 in Coal
- Author
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Qinghe Niu, Shuxun Sang, Liwen Cao, Xiaozhi Zhou, and Zhenzhi Wang
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Materials science ,business.industry ,020209 energy ,General Chemical Engineering ,Compaction ,Energy Engineering and Power Technology ,02 engineering and technology ,Permeability (earth sciences) ,Fuel Technology ,Bed ,Thermal ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Coal ,Composite material ,Swelling ,medicine.symptom ,business ,Anisotropy ,Porosity - Abstract
The changes of anisotropic adsorption–swelling and permeability with injecting CO2 in coal influence the CO2 injectivity during CO2-ECBM or CGS (ECBM = enhancing coal bed methane; CGS = CO2 geological sequestration). To strengthen the understanding of this issue, two special-made cubic coal samples were adopted to test the porosity, swelling, and permeability in parallel face cleat and bedding plane direction, parallel butt cleat and bedding plane direction, and vertical bedding plane direction. To quantitatively characterize the anisotropic porosity, anisotropic swelling, and anisotropic permeability, an anisotropy index was introduced in this work. The results show that porosity anisotropy reflects the pore connectivity in different directions, which fall in the order of parallel face cleat and bedding plane direction > parallel butt cleat and bedding plane direction > vertical bedding plane direction. The porosity varieties can be owed to the compaction effect, thermal evolution effect, banded structur... more...
- Published
- 2018
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34. Cyclic strength of loose anisotropically-consolidated calcareous sand under standing waves and assessment using the unified cyclic stress ratio
- Author
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Yumin Chen, Xiaozhi Zhou, Armin W. Stuedlein, and Hanlong Liu
- Subjects
Stress (mechanics) ,Shear (sheet metal) ,Standing wave ,Materials science ,Amplitude ,Consolidation (soil) ,Cylinder stress ,Geology ,Mechanics ,Geotechnical Engineering and Engineering Geology ,Instability ,Seabed - Abstract
Progressive and standing waves can produce instability of the seabed and seabed-supported marine structures. In this paper, the stress paths induced by standing waves were deduced to provide a theoretical basis for laboratory element tests to establish the cyclic behavior of marine sediments, which can serve to improve the understanding of seabed liquefaction triggering and its consequences. The cyclic response of loose, isotropically- and anisotropically-consolidated (IC and AC, respectively) calcareous sand under the stress paths derived for standing waves was examined using hollow cylinder torsional shear (HCTS) tests. The stress paths corresponding to standing waves are a vertical line, horizontal line, and ellipse, in a coordinate system consisting of the axial stress difference and the horizontal shear stress, for a soil element located at the nodes, antinodes, and intermediate horizontal positions, respectively. The phase difference, θ, between axial stress difference and horizontal shear stress appears to range from −45° ~ 7° for wave and seabed characteristics representative of the North Sea. The ratio of axial stress difference and horizontal shear stress amplitudes, λ, varies in the real number field. The experimental results indicated that the failure modes of IC and AC specimens are cyclic mobility and residual deformation failure, respectively, irrespective of the stress paths imposed. With the same consolidation state and cyclic stress ratio, CSR, the number of cycles to failure, Nf, is strongly affected by θ and λ. The unified cyclic stress ratio, USR, is proposed to establish a single USR-Nf curve that can suitably describe the general cyclic strength of the calcareous sand specimens under different stress paths for a given consolidation stress ratio. The proposed USR enables estimation of the cyclic strength of IC and AC soils under complex stress paths based on the CSR-Nf curve obtained from conventional cyclic torsional shear or triaxial tests. more...
- Published
- 2021
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35. The adsorption-swelling and permeability characteristics of natural and reconstituted anthracite coals
- Author
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Liwen Cao, Qinghe Niu, Shuxun Sang, Zhiyong Wu, Xiaozhi Zhou, and Zhenzhi Wang
- Subjects
Materials science ,020209 energy ,02 engineering and technology ,010502 geochemistry & geophysics ,complex mixtures ,01 natural sciences ,Industrial and Manufacturing Engineering ,Adsorption ,Specific surface area ,otorhinolaryngologic diseases ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Coal ,Electrical and Electronic Engineering ,Composite material ,0105 earth and related environmental sciences ,Civil and Structural Engineering ,Petroleum engineering ,business.industry ,Mechanical Engineering ,technology, industry, and agriculture ,Anthracite ,Coal mining ,Building and Construction ,respiratory system ,Intergranular corrosion ,Pollution ,respiratory tract diseases ,Permeability (earth sciences) ,General Energy ,Swelling ,medicine.symptom ,business - Abstract
To fundamentally study the adsorption capacity, swelling effect and permeability characteristic of coal seams with and without tectonic damage, the natural coal and reconstituted coal manufactured via simulating in situ geological conditions were investigated. The results show that the reconstituted coal possesses higher adsorption equilibrium time and maximum adsorption capacity comparing to the natural coal. The multitudinous intergranular seepage paths and large specific surface area of it supply adequate opportunities and sites for adsorption of injected gas. The anisotropy swelling was observed in the natural coal, which is manifested as that the axial swelling strain surpasses the radial swelling strain. Contrarily, the swelling strain of reconstituted coal is approximated to homogeneous and isotropic variety. The natural coal possesses swelling hysteresis phenomenon in the low adsorption stage, this is because of the deformation sequence from internal swelling to volume swelling conducted in it. The permeability of natural coal and reconstituted coal decreases remarkably after being saturated CO2 and N2. Especially, the permeability sensitivity of reconstituted coal is higher than natural coal and has enormous decreasing amplitude after injected high-pressure CO2, which reveals us that weak coal seams may be the unstable areas for CO2-ECBM or CGS in deep coal seams. more...
- Published
- 2017
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36. Experimental study on the softening effect and mechanism of anthracite with CO2 injection
- Author
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Zhongmin Ji, Liwen Cao, Chang Jiangfang, Qinghe Niu, Shuxun Sang, Xiaozhi Zhou, Wei Yuan, Wei Wang, and Mengyang Li
- Subjects
Materials science ,Coalbed methane ,business.industry ,technology, industry, and agriculture ,0211 other engineering and technologies ,Anthracite ,Coal mining ,02 engineering and technology ,Geotechnical Engineering and Engineering Geology ,complex mixtures ,Supercritical fluid ,Coal ,Composite material ,business ,Saturation (chemistry) ,Elastic modulus ,Softening ,021102 mining & metallurgy ,021101 geological & geomatics engineering - Abstract
The injection of supercritical CO2 into coal seam alters the mechanical properties of the coal, which should be paid close attention when considering security issues during CO2-Enhanced CoalBed Methane recovery (CO2-ECBM). In this study, the Qinshui Basin is considered as the research object, and mechanical parameters, such as the peak strength, elastic modulus, and Poisson's ratio of anthracites under the coupled influences of CO2 saturation pressure, CO2 saturation time, and water content were investigated. The results indicate a decrease in the peak strength and elastic modulus and an increase in the Poisson's ratio of the CO2-saturated coal. Increasing the CO2 saturation pressure, extending the CO2 saturation time, and increasing the water content contributes to the softening of the coal. The modified Langmuir equation and stretched exponential (SE) equation are used to accurately predict the peak strength and elastic modulus reduction with CO2 saturation pressure and CO2 saturation time, respectively. The failure patterns change from brittle shear failure for natural coal and transitional shear failure for supercritical CO2-saturated coal to the ductile non-dilatant barreling for the supercritical CO2+water-saturated coal. The softening effect of coal can be attributed to the chemical and physical reactions between coal and CO2, including the surface energy reduction of CO2-bearing coal, extraction and plasticization reactions, differential adsorption swelling and swelling stress, and dissolution of carbonate solution for the mineral filling pore/fracture. In view of the geo-mechanical changes caused by CO2 to coal, the optimization of the targeted reservoir is pivotal for the successful implementation of CO2-ECBM. more...
- Published
- 2021
- Full Text
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37. Selection of suitable engineering modes for CBM development in zones with multiple coalbeds: A case study in western Guizhou Province, Southwest China
- Author
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Youbiao Hu, Shuxun Sang, Jin Jun, Huihu Liu, Bo Ren, Xiaozhi Zhou, Jianshuo Li, Hongjie Xu, and Yang Jingfen
- Subjects
Hydrogeology ,Petroleum engineering ,Coalbed methane ,Mode selection ,business.industry ,020209 energy ,Method engineering ,Coal mining ,Energy Engineering and Power Technology ,02 engineering and technology ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Tectonics ,Fuel Technology ,Mining engineering ,0202 electrical engineering, electronic engineering, information engineering ,Coal ,business ,Geology ,0105 earth and related environmental sciences - Abstract
Recently, many types of coalbed methane (CBM) engineering practices have been applied in western Guizhou. However, most of these CBM practices (e.g., vertical well, horizontal well, cluster well.) have failed due to the complex geological conditions. To improve the success rate of CBM development projects, this paper proposes a CBM engineering mode selection method based on the geological conditions of the CBM resources found in western Guizhou. By analyzing the geology and considering the Upper Permian coal seams in western Guizhou as a case study, the geological conditions associated with CBM development were examined using measured data. In addition, the selective matching of existing CBM engineering methods to the geological conditions was examined and preliminarily demonstrated. The results indicated that the evolution of the geological conditions was primarily controlled by the vertical distribution of the coal strata, the hydrogeological conditions, and the tectonic stresses. The classification of the geological conditions into different types of CBM development geology was conducted according to the regional configuration of the geological parameters. A basic relationship exists between the type of geology and the engineering method for CBM development. To optimize the development engineering method and obtain high CBM production, the engineering methods of thin-layer staged fracturing of multiple coal seams, supplementary fracturing of sandstone reservoirs in coal deposits, and reservoir stimulation via protected coal seams during mining were preliminarily established. These methods represent a new direction for the CBM development of thin to moderate coal seams in western Guizhou. The technical feasibilities of the selected CBM development methods were verified by engineering practices, and certain CBM wells reported good production. This study describes the engineering effectiveness and adaptability of CBM engineering practices from the perspective of the development methods in the study area. In addition, this study emphasizes that the relationships between the geological conditions and the engineering methods might be broadly applicable when choosing the best CBM development engineering method for zones with multiple coalbeds in China. more...
- Published
- 2016
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38. A case study on the effective stimulation techniques practiced in the superposed gas reservoirs of coal-bearing series with multiple thin coal seams in Guizhou, China
- Author
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Liwen Cao, Yi Tongsheng, Jinlong Jia, Shuxun Sang, and Xiaozhi Zhou
- Subjects
Coalbed methane ,Petroleum engineering ,business.industry ,Stimulation technique ,Coal mining ,Drilling ,02 engineering and technology ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Fracture geometry ,Fuel Technology ,Hydraulic fracturing ,020401 chemical engineering ,Mining engineering ,Low permeability ,Coal ,0204 chemical engineering ,business ,Geology ,0105 earth and related environmental sciences - Abstract
The superposed reservoirs of coal-bearing series represent a new type of gas reservoir associated with coal seams, and those with multiple thin coal seams are an important subtype popular in Guizhou, an emerging area for coal-bearing series gas exploitation in China. So it is significance to accommodate hydraulic fracturing, a common stimulation technique for enhanced gas recovery from low permeability reservoirs, to the reservoirs there. Based on a number of engineering and test data from Songhe pilot project for coal seam gas recovery in Guizhou, this paper presents some effective stimulation techniques adapting to the superposed reservoirs of coal-bearing series with multiple thin coal seams, including drilling and well completion selection, gas-bearing intervals targeting, small-layer perforation, staged fracturing, ball sealer diversion and graded proppant injection. The study also focuses on the mechanism on adaptable hydraulic fracturing of the superposed reservoirs associated with multiple thin coal seams, by combining theoretical analyses and actual fracturing curve diagnoses. The results indicate that the fractures opening exhibit a certain temporal order depend on mechanical and other physical properties differences among individual perforated intervals, and the fracture opening sequence can be controlled by adjusting pumping scheme and dropping ball sealers; the fracture height extended into the adjacent rocks is a critical geometric parameter affecting scale of fracture network, and negatively correlated with tensile strength difference between coal seams and adjacent rocks; under a condition of the current maximum pump rate, the fracturing treatment in both multiple thin coal seams and interlayered sandstones have been implemented, and a fracture network has been generated with a uniform fracture geometry and strong flow conductivity by the combined application of the effective stimulation techniques. more...
- Published
- 2016
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39. Evaluation of coal and shale reservoir in Permian coal-bearing strata for development potential: A case study from well LC-1# in the northern Guizhou, China
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Jin Jun, Yang Jingfen, Huihu Liu, Xiaozhi Zhou, Hongjie Xu, Gao Wei, and Shuxun Sang
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Coalbed methane ,Permian ,Shale gas ,lcsh:TJ807-830 ,0211 other engineering and technologies ,Geochemistry ,lcsh:Renewable energy sources ,Energy Engineering and Power Technology ,02 engineering and technology ,010502 geochemistry & geophysics ,01 natural sciences ,law.invention ,law ,lcsh:TK1001-1841 ,Coal ,021108 energy ,China ,0105 earth and related environmental sciences ,Bearing (mechanical) ,Renewable Energy, Sustainability and the Environment ,business.industry ,Unconventional oil ,lcsh:Production of electric energy or power. Powerplants. Central stations ,Fuel Technology ,Nuclear Energy and Engineering ,business ,Oil shale ,Geology - Abstract
Indentifying reservoir characteristics of coals and their associated shales is very important in understanding the co-exploration and co-production potential of unconventional gases in Guizhou, China. Accordingly, comprehensive experimental results of 12 core samples from well LC-1# in the northern Guizhou were used and analyzed in this paper to better understand their vertical reservoir study. Coal and coal measured shale, in Longtan Formation, are rich in organic matter, with postmature stage of approximately 3.5% and shales of type III kerogen with dry gas generation. All-scale pore size analysis indicates that the pore size distribution of coal and shale pores is mainly less than 20 nm and 100 nm, respectively. Pore volume and area of coal samples influenced total gas content as well as desorbed gas and lost gas content. Obvious relationships were observed between residual gas and BET specific surface area and BJH total pore volume (determined by nitrogen adsorption). For shale, it is especially clear that the desorbed gas content is negatively correlated with BET specific surface area, BJH total pore volume and clay minerals. However, the relationships between desorbed gas and TOC (total organic carbon) as well as siderite are all well positive. The coals and shales were shown to have similar anoxic conditions with terrestrial organic input, which is beneficial to development of potential source rocks for gas. However, it may be better to use a low gas potential assessment for shales in coal-bearing formation because of their low S1+S2 values and high thermal evolution. Nevertheless, the coalbed methane content is at least 10 times greater than the shale gas content with low desorbed gases, indicating that the main development unconventional natural gas should be coalbed methane, or mainly coalbed methane with supplemented shale gas. more...
- Published
- 2019
40. Study on the anisotropic permeability in different rank coals under influences of supercritical CO2 adsorption and effective stress and its enlightenment for CO2 enhance coalbed methane recovery
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Wei Yuan, Shuxun Sang, Xiaozhi Zhou, Haichao Wang, Yan Nie, Liwen Cao, Wei Wang, Zhongmin Ji, and Qinghe Niu
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Materials science ,Coalbed methane ,business.industry ,020209 energy ,General Chemical Engineering ,Effective stress ,Organic Chemistry ,Coal mining ,Compaction ,Energy Engineering and Power Technology ,Soil science ,02 engineering and technology ,Permeability (earth sciences) ,Fuel Technology ,020401 chemical engineering ,Bed ,0202 electrical engineering, electronic engineering, information engineering ,Coal ,0204 chemical engineering ,business ,Saturation (chemistry) - Abstract
The permeability of coal reservoir is dynamically changed during CO2 enhance coalbed methane recovery projects (CO2-ECBM) and is controlled by the two main influencing factors: effective stress and CO2 adsorption. Six coal core samples parallel and vertical bedding plane directions were drilled, which were then adopted to conduct the permeability tests under conditions of cyclic loading/unloading and supercritical CO2 saturation. Results show that the permeability is depended on the coal rank, the middle rank coal possesses the highest initial permeability because of its moderate compaction and largely generated cleats during the coalification. The permeability is anisotropic, manifesting in the permeability in parallel bedding plane direction is larger than that in the vertical bedding plane direction. The stress sensitivity coefficient and IPLRi in parallel bedding plane direction exceed that in vertical bedding plane direction, however, PALR exhibits the opposite law. Hereat, the fractures parallel to bedding plane are susceptible to the stress change and the cleats vertical to bedding plane are sensitive to the ScCO2 adsorption. In view of the irreversible permeability damage by the stress change and CO2 adsorption, experiments in this paper confirms that prefracturing can dramatically decrease the IPLRi, stress sensitivity coefficient and PALR of coal seams, which may be the potential and effective measure to enhence the injectivity of CO2 in coal seams. more...
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- 2020
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41. A quasi-three-dimensional spring-deformable-block model for runout analysis of rapid landslide motion
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L. Lu, Y.F. Lan, Haiqing Yang, and Xiaozhi Zhou
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Acceleration ,Conservation of energy ,Deformation (mechanics) ,Spring (device) ,Geology ,Geotechnical engineering ,Landslide ,Geotechnical Engineering and Engineering Geology ,Stability (probability) ,Displacement (vector) ,Discrete element method ,Physics::Geophysics - Abstract
Assessment of landslide hazard often requires a good knowledge of the landslide characteristics. To investigate the dynamic runout process of the landslide across a 3D terrain, a quasi-three-dimensional model using spring-deformable-block model is proposed. On the assumption that the motion of landslides is continuous and variable, the sliding body is divided into lots of columns. The model is based on a stability analysis of landslides and allows the deformation of sliding body. Considering the force and moment equilibrium of deformable columns and the principle of conservation of energy, a quasi-three-dimensional sliding body is simplified by a series of deformable blocks with different dimensions. Then, the sliding body acceleration, velocity and displacement formulas are established accordingly. Correlating relatively well with the discrete element method, the present results are satisfactory in describing the dynamic process of landslides and predicting the impact areas of the post-failure sliding body. Finally, the present model is applied to analyze the sliding time, the maximum velocity and displacement of the sliding body of Jiweishan landslide in Wulong, Chongqing Southern China. When comparing with distinct element method, the model shows generally good agreement with them. more...
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- 2015
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42. Analysis of the excavation damaged zone around a tunnel accounting for geostress and unloading
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Y.F. Lan, Y.Y. Zeng, Xiaozhi Zhou, and Haiqing Yang
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Engineering ,Computer simulation ,business.industry ,Constitutive equation ,Excavation ,Structural engineering ,Tunnel engineering ,Geotechnical Engineering and Engineering Geology ,Tangential stress ,Geotechnical engineering ,business ,Rock mass classification ,Radial stress ,Analysis method - Abstract
A simplified analysis method based on the damage evolution mechanism of rock mass is proposed to predict the possible excavation damaged zone around a tunnel. The formation of an excavation damaged zone is dependent on three main aspects: time-dependent macroscopic stress field during excavation, constitutive model under unloading condition, and initial microcracks. The excavation process is simplified as a time-dependent increase of the radius. For the tunnel problem, the tangential stress is under loading, while the radial stress is under unloading condition. As the macroscopic stress redistribution, the constitutive relationships which can take unloading state into account are coupled in this model. Then, in order to simulation the damage evolution process of surrounding rock mass, the sliding crack model and equivalent crack method are adopted. The different constitutive curve between loading and unloading state is discussed through examples. The efficiency of the proposed model is verified with the experimental and numerical simulation data available. The results of the proposed analytical model are in good agreement with the test results and, therefore, this model can be used in the preliminary tunnel design to evaluate tunnel stability, especially for the tunnel engineering at high geostress zone. more...
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- 2014
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43. Municipal solid waste degradation and landfill gas resources characteristics in self-recirculating sequencing batch bioreactor landfill
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Liwen Cao, Xiaozhi Zhou, and Shuxun Sang
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Hydrolysis ,Bioreactor landfill ,Municipal solid waste ,Landfill gas ,Waste management ,Small range ,Metals and Alloys ,General Engineering ,Environmental science ,Degradation (geology) ,Leachate ,Mass fraction - Abstract
Based on the degradation characteristics of municipal solid waste (MSW) in China, the traditional anaerobic sequencing batch bioreactor landfill (ASBRL) was optimized, and an improved anaerobic sequencing batch bioreactor landfill (IASBRL) was put forward on the basis of leachate self-recirculation. By monitoring MSW composition, leachate characteristics variation and landfill gas (LFG) generation, the effect of IASBRL was comparatively studied by simulation landfill. Based on the adjusting, scouring and carrying effects of leachate self-recirculation, IASBRL can rapidly decrease Eh value to about −500 mV and form a suitable biochemical environment for methanogens, which provides a precondition for stable cooperation between non-methanogens and methanogens. IASBRL can avoid the accumulation of organic acids, make VFA (volatile fatty acid) concentration and CODCr decrease along with the small range fluctuations, and form a stable decomposition-consumption synergy during MSW degradation, therefore, the hydrolysis rate of easy hydrolyze material reaches 71.2% in IASBRL. From the viewpoint of LFG resources in IASBRL, the cumulative LFG production increases to 2 327.0 L, CH4 mass fraction stabilizes at about 50%, and these provide a favorable precondition for LFG development. more...
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- 2012
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44. Mechanical model of yaw damper and its application in the simulation of vehicle system dynamics
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Li Huang, Xiaozhi Zhou, Ye Song, and Jing Zeng
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020303 mechanical engineering & transports ,0203 mechanical engineering ,Control theory ,Computer science ,Yaw damper ,020302 automobile design & engineering ,02 engineering and technology ,System dynamics - Published
- 2018
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45. A nurse-led structured education program improves self-management skills and reduces hospital readmissions in patients with chronic heart failure: a randomized and controlled trial in China.
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Xiaoning Cui, Xiaozhi Zhou, Long-le Ma, Tong-Wen Sun, Bishop, Lara, Gardiner, Fergus W., and Wang, Lexin
- Abstract
Introduction: Patient self-management skills are an important part of heart failure (HF) management. However, there is a lack of knowledge about the effectiveness of nurse-led education on patient self-management and the associated clinical outcomes of rural Chinese patients with chronic heart failure (CHF). As such, this study was designed to evaluate the impact of a nurse-led education program on patient self-management and hospital readmissions in rural Chinese patients with CHF. Methods: Ninety-six patients in the eastern Chinese province of Shandong with CHF were randomly divided into intervention and control groups. A structured education program was delivered to the intervention group during hospitalization and after discharge. Control group patients were managed as per clinical guidelines without structured education. Medication adherence, dietary modifications, social support, and symptom control were assessed 12 months after the educational intervention. Results: The mean score of medication adherence, dietary modifications, social support and symptom control in the intervention group was higher than in the control group at the end of the study (p<0.01). The readmission rates for HF in the intervention and control group were 10.4% and 27.1%, respectively (p=0.036). Conclusions: This study has demonstrated that a structured education program was associated with a significant improvement in medication adherence, dietary modifications, social support, and symptom control in rural CHF patients. Furthermore, this program was associated with a significant reduction in hospital readmission. This study indicates that implementation of a nurse-led education program improves self-management and clinical outcomes of rural CHF patients, who may not have regular access to cardiac management services as per metropolitan populations. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
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46. Simulation Experiment of the Anaerobic Degradation Law of Municipal Solid Waste
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Liwen Cao, Xiaozhi Zhou, Shuxun Sang, Yunhuan Cheng, and Liu Huihu
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chemistry.chemical_classification ,chemistry.chemical_compound ,Chemistry ,Environmental chemistry ,Humic acid ,Degradation (geology) ,Lignin ,Hemicellulose ,Cellulose ,Thermal hydrolysis ,Humus ,Waste disposal - Abstract
Using four sets of self-designed devices, the simulation experiment was carried out, which lasted 11 months. By monitoring the content of volatile solid, fats, crude fiber and humic acid, the anaerobic degradation law of the organic fraction of municipal solid waste (OFMSW) was studied. The results show that: (1) OFMSW degradation amount takes up 82.3% of the total at the acidification stage, so the acidification stage is the main period of OFMSW degradation. (2) Methanation inhibits the degradation of fats strongly, and the fats degradation rate decreases from 4.4 g-kg -1 -d -1 to 0.4 g-kg -1 -d -1 rapidly at the methanation stage. (3) There is great difference among the degradation degree of hemicellulose, cellulose and lignin, and their degradation rates are 66.9%, 51.6% and 7.3% respectively. Hemicellulose/lignin and cellulose/lignin decrease linearly with degradation time, which can be used as a stabilization evaluation index in the process of OFMSW degradation. (4) LFG disturbance action and pH increase are two possible reasons to lead the total extractable hymatomelanic acid and humus acid decrease rapidly along with LFG production increase. more...
- Published
- 2009
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47. Anisotropic Adsorption Swelling and Permeability Characteristics with Injecting CO2 in Coal.
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Qinghe Niu, Liwen Cao, Shuxun Sang, Xiaozhi Zhou, and Zhenzhi Wang
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- 2018
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48. Simulation Study on the Dehydration and Settlement Characteristics of Surface Waste in Landfill
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Xiaozhi, Zhou, primary, Shuxun, Sang, additional, Liwen, Cao, additional, and Yunhuan, Cheng, additional
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- 2012
- Full Text
- View/download PDF
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