The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform
Pengfei Ren - One of the best experts on this subject based on the ideXlab platform.
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geological conditions of deep coalbed methane in the eastern margin of the ordos basin china implications for coalbed methane development
Journal of Natural Gas Science and Engineering, 2018Co-Authors: Dazhen Tang, Zhejun Pan, Shu Tao, Yanfei Liu, Pengfei RenAbstract:Abstract Deep coalbed methane (CBM) resource potential is enormous in China, and has become a new field for unconventional natural gas exploration and development. This work discusses the geological conditions (reservoir pressure, formation temperature and ground stress) of deep coal reservoirs in the Eastern margin of the Ordos Basin and their implication on CBM development. Various field Test data of CBM wells, including injection/drawdown Test data, well temperature Test data, and hydraulic Fracturing Test data were collected from this work and literature to describe the geological conditions of the deep CBM in the study area. From the results, it is found that deep CBM in this area is characterized by high reservoir pressure, high formation temperature, and high ground stress. However, there are diverse geological particularities in the different depth range: (1) Having a wide range of pressure gradient, vast majority of coal reservoirs in the study area are under abnormally low-pressure state, which is more significant in deeper coal seams. (2) Due to the impact of surface runoff, the distribution of geothermal gradient is discrete when the burial depth is less than 700 m, and relatively concentrated when the burial depth is greater than 700 m. (3) In shallow coal reservoirs, ground stress is strongest in the horizontal direction; while in deep coal reservoirs, the strongest ground stress is in the vertical direction. Because of the complex geological conditions associated with deep burial, the balance between CBM adsorption-desorption-seepage and the rheological behavior of coal reservoirs is complex, which has significant influence on the exploration and development of deep CBM in the study area. High pressure in deep coal reservoir often leads a long inefficient desorption stage and a long draining and depressurizing process, which increases production costs. Moreover, the negative temperature effect on gas adsorption indicates that CBM content decreases with increasing depth in deep conditions, and thus the evaluation of deep CBM resources needs to be reconsidered. In addition, different stress states govern fracture patterns, and in deep environments, high ground stress greatly reduces the Fracturing improvement of the coal reservoir and significantly affects the deep CBM development.
Quanjie Zhu - One of the best experts on this subject based on the ideXlab platform.
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interpretation of the extent of hydraulic Fracturing for rockburst prevention using microseismic monitoring data
Journal of Natural Gas Science and Engineering, 2017Co-Authors: Quanjie Zhu, Yu Feng, Ming Cai, Jinhai Liu, Honghui WangAbstract:Abstract As the mining depths increase, an increasing number of deep coal mines in China encounter frequent intense rockburst problems. Conventional destress measures, employed effectively in shallow mines to reduce rockburst risk, are not suitable to deep coal mines because they are labor-intensive and time-consuming and hence are costly. Hydraulic Fracturing in coal seams before mining a particular area has been considered as an effective destressing method for rockburst prevention. This paper focuses on using microseismic data to evaluate the extent of hydraulic Fracturing in coal seams. To that purpose, innovative methods are proposed to process and interpret microseismic monitoring data. The proposed methods consist of an improved HHT method for signal filtering, an improved time-window energy eigenvalue method for first arrival picking, and a four-channel combined algorithm for seismic source location determination. Using the elaborate signal processing and interpretation methods, high-precision source locations of microseismic events recorded in a field hydraulic Fracturing Test at Huafeng Coal Mine are obtained. Microseismic event frequency and energy contours are plotted to characterize the fracture development and propagation process. The interpretation method was successfully applied in the coal seam hydraulic Fracturing Tests. Direct field observation and stress monitoring were also conducted to verify the results by the microseismic data interpretation method. Compared with conventional monitoring techniques such as stress monitoring and direct field observation, microseismic monitoring can cover a large monitoring volume with a high response sensitivity and it can capture the spatial-temporal fracture evolution process easily. It provides a practical approach to quantify the extent of hydraulic Fracturing in coal seams for rockburst prevention.
Ruud Weijermars - One of the best experts on this subject based on the ideXlab platform.
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impact on drained rock volume drv of storativity and enhanced permeability in naturally fractured reservoirs upscaled field case from hydraulic Fracturing Test site hfts wolfcamp formation midland basin west texas
Energies, 2019Co-Authors: Kiran Nandlal, Ruud WeijermarsAbstract:Hydraulic Fracturing for economic production from unconventional reservoirs is subject to many subsurface uncertainties. One such uncertainty is the impact of natural fractures in the vicinity of hydraulic fractures in the reservoir on flow and thus the actual drained rock volume (DRV). We delineate three fundamental processes by which natural fractures can impact flow. Two of these mechanisms are due to the possibility of natural fracture networks to possess (i) enhanced permeability and (ii) enhanced storativity. A systematic approach was used to model the effects of these two mechanisms on flow patterns and drained regions in the reservoir. A third mechanism by which natural fractures may impact reservoir flow is by the reactivation of natural fractures that become extensions of the hydraulic fracture network. The DRV for all three mechanisms can be modeled in flow simulations based on Complex Analysis Methods (CAM), which offer infinite resolution down to a micro-fracture scale, and is thus complementary to numerical simulation methods. In addition to synthetic models, reservoir and natural fracture data from the Hydraulic Fracturing Test Site (Wolfcamp Formation, Midland Basin) were used to determine the real-world impact of natural fractures on drainage patterns in the reservoir. The spatial location and variability in the DRV was more influenced by the natural fracture enhanced permeability than enhanced storativity (related to enhanced porosity). A Carman–Kozeny correlation was used to relate porosity and permeability in the natural fractures. Our study introduces a groundbreaking upscaling procedure for flows with a high number of natural fractures, by combining object-based and flow-based upscaling methods. A key insight is that channeling of flow through natural fractures left undrained areas in the matrix between the fractures. The flow models presented in this study can be implemented to make quick and informed decisions regarding where any undrained volume occurs, which can then be targeted for reFracturing. With the method outlined in our study, one can determine the impact and influence of natural fracture sets on the actual drained volume and where the drainage is focused. The DRV analysis of naturally fractured reservoirs will help to better determine the optimum hydraulic fracture design and well spacing to achieve the most efficient recovery rates.
Dazhen Tang - One of the best experts on this subject based on the ideXlab platform.
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geological conditions of deep coalbed methane in the eastern margin of the ordos basin china implications for coalbed methane development
Journal of Natural Gas Science and Engineering, 2018Co-Authors: Dazhen Tang, Zhejun Pan, Shu Tao, Yanfei Liu, Pengfei RenAbstract:Abstract Deep coalbed methane (CBM) resource potential is enormous in China, and has become a new field for unconventional natural gas exploration and development. This work discusses the geological conditions (reservoir pressure, formation temperature and ground stress) of deep coal reservoirs in the Eastern margin of the Ordos Basin and their implication on CBM development. Various field Test data of CBM wells, including injection/drawdown Test data, well temperature Test data, and hydraulic Fracturing Test data were collected from this work and literature to describe the geological conditions of the deep CBM in the study area. From the results, it is found that deep CBM in this area is characterized by high reservoir pressure, high formation temperature, and high ground stress. However, there are diverse geological particularities in the different depth range: (1) Having a wide range of pressure gradient, vast majority of coal reservoirs in the study area are under abnormally low-pressure state, which is more significant in deeper coal seams. (2) Due to the impact of surface runoff, the distribution of geothermal gradient is discrete when the burial depth is less than 700 m, and relatively concentrated when the burial depth is greater than 700 m. (3) In shallow coal reservoirs, ground stress is strongest in the horizontal direction; while in deep coal reservoirs, the strongest ground stress is in the vertical direction. Because of the complex geological conditions associated with deep burial, the balance between CBM adsorption-desorption-seepage and the rheological behavior of coal reservoirs is complex, which has significant influence on the exploration and development of deep CBM in the study area. High pressure in deep coal reservoir often leads a long inefficient desorption stage and a long draining and depressurizing process, which increases production costs. Moreover, the negative temperature effect on gas adsorption indicates that CBM content decreases with increasing depth in deep conditions, and thus the evaluation of deep CBM resources needs to be reconsidered. In addition, different stress states govern fracture patterns, and in deep environments, high ground stress greatly reduces the Fracturing improvement of the coal reservoir and significantly affects the deep CBM development.
Honghui Wang - One of the best experts on this subject based on the ideXlab platform.
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interpretation of the extent of hydraulic Fracturing for rockburst prevention using microseismic monitoring data
Journal of Natural Gas Science and Engineering, 2017Co-Authors: Quanjie Zhu, Yu Feng, Ming Cai, Jinhai Liu, Honghui WangAbstract:Abstract As the mining depths increase, an increasing number of deep coal mines in China encounter frequent intense rockburst problems. Conventional destress measures, employed effectively in shallow mines to reduce rockburst risk, are not suitable to deep coal mines because they are labor-intensive and time-consuming and hence are costly. Hydraulic Fracturing in coal seams before mining a particular area has been considered as an effective destressing method for rockburst prevention. This paper focuses on using microseismic data to evaluate the extent of hydraulic Fracturing in coal seams. To that purpose, innovative methods are proposed to process and interpret microseismic monitoring data. The proposed methods consist of an improved HHT method for signal filtering, an improved time-window energy eigenvalue method for first arrival picking, and a four-channel combined algorithm for seismic source location determination. Using the elaborate signal processing and interpretation methods, high-precision source locations of microseismic events recorded in a field hydraulic Fracturing Test at Huafeng Coal Mine are obtained. Microseismic event frequency and energy contours are plotted to characterize the fracture development and propagation process. The interpretation method was successfully applied in the coal seam hydraulic Fracturing Tests. Direct field observation and stress monitoring were also conducted to verify the results by the microseismic data interpretation method. Compared with conventional monitoring techniques such as stress monitoring and direct field observation, microseismic monitoring can cover a large monitoring volume with a high response sensitivity and it can capture the spatial-temporal fracture evolution process easily. It provides a practical approach to quantify the extent of hydraulic Fracturing in coal seams for rockburst prevention.
