Critical tectonic events and their geological controls on deep buried coalbed methane accumulation in Daning-Jixian Block, eastern Ordos Basin

Yan, Taotao; He, Shan; Zheng, Shuai; Bai, Yubin; Chen, Wei; Meng, Yanjun; Jin, Shangwen; Yao, Hongxun; Jia, Xiaobao

doi:10.1007/s11707-022-1000-7

Cited by 7 publications

(7 citation statements)

References 20 publications

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“…The adsorbed gas is mainly adsorbed on the surface of the coal matrix and clay mineral particles, and the free gas is mainly distributed in the large pores and fractures of the coal. Yang et al and Li et al found that the deep coal seam in the eastern margin of the Ordos Basin is in a state of supersaturation with respect to gas content overall and that the proportion of free gas is 17-34%, with an average of approximately 20%, which is characterized by "high gas content, high gas saturation, and rich free gas" [60][61][62][63]. Tang et al and Ma et al studied the relationship between the pore structure at different scales and the gas content characteristics of deep coal reservoirs in the Daning-Jixian block.…”

Section: Comprehensive Characteristics Of Full-scale Pores Andmentioning

confidence: 99%

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Full-Scale Pore and Microfracture Characterization of Deep Coal Reservoirs: A Case Study of the Benxi Formation Coal in the Daning–Jixian Block, China

Wang,

Zhou,

Fan

et al. 2024

International Journal of Energy Research

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The pore-fracture structure of deep coal reservoirs is highly important for evaluating, exploring, and developing coalbed methane (CBM) resources. This study considers three coal samples from the DJ57 well in the Benxi Formation in the Daning–Jixian block on the eastern margin of the Ordos Basin as the research object. Based on the coal quality parameters of the coal samples, field emission scanning electron microscopy (FE-SEM), gas adsorption experiments, high-pressure mercury intrusion porosimetry (MIP), and microcomputed tomography (micro-CT) scanning were used to quantitatively characterize the nanoscale pores and microscale fractures in deep coal reservoirs and to evaluate the pore-fracture structure at different scales. The results reveal that the pore types in the Benxi Formation coal samples are diverse and include mainly organic matter (OM) pores, inorganic pores (intraparticle and interparticle pores), and microfractures. The organic pores are diverse in shape and mainly exhibit round, oval, and wedge shapes, while the microfractures exhibit slender stripes or serrated curves. The multiscale quantitative characterization of deep coal reservoir pores and fractures is based on a variety of pore characterization methods, and the pore and fracture volume distributions are mainly U-shaped, revealing the coexistence of micropores and microfractures. The volumes of micropores (0.3–2 nm), mesopores (2–50 nm), macropores (50 nm to 10 μm), and microfractures (>10 μm) account for 78.00%, 6.78%, 2.08%, and 13.14%, respectively, of the total pore volume (PV). Based on a full-scale pore-fracture splicing calculation, the total permeability of the Benxi Formation coal samples ranges from 5.77 to 28.22 mD. The observation results indicate that the microfractures are connected to each other, forming a network structure with strong connectivity. The microfractures are mainly associated with pore diameters>100 μm, accounting for approximately 95% of the total permeability. Moreover, micropores in deep coal reservoirs provide a large space for CBM adsorption, and microfractures enhance the seepage capacity of CBM.

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Section: Comprehensive Characteristics Of Full-scale Pores Andmentioning

confidence: 99%

“…Figure17: Relationships between the multiscale pore-fracture structure and gas content of the coal samples[60,61]. (a) Micropore PV vs. adsorbed gas volume, (b) micropore SSA vs. adsorbed gas volume, (C) micropore PV vs. free gas volume, and (d) micropore SSA vs. free gas volume.…”

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confidence: 99%

Full-Scale Pore and Microfracture Characterization of Deep Coal Reservoirs: A Case Study of the Benxi Formation Coal in the Daning–Jixian Block, China

Wang,

Zhou,

Fan

et al. 2024

International Journal of Energy Research

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“…This study area encompasses a large west-dipping monocline, situated within two tectonic units, including the Guyi-Yaoqu uplift and the Xueguan-Yukou depression [35]. The faults primarily follow a NE or NNE direction [36]. The main coal-bearing strata belong to the Carboniferous-Permian period, comprising the Shanxi Formation and the Taiyuan Formation.…”

Section: Geological Settingmentioning

confidence: 99%

Quantitative Prediction of Deep Coalbed Methane Content in Daning-Jixian Block, Ordos Basin, China

Ouyang,

Wang,

Sun

et al. 2023

Processes

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The potential of deep coalbed methane resources is substantial. Gas content is an important parameter for resource assessment. At present, the gas content test method commonly used for shallow coal reservoirs is not suitable for determining deep coalbed methane gas content. Therefore, it is urgent to establish a prediction method for deep coalbed methane gas content. This study aims to quantitatively predict the gas content of coalbed methane in deep coal reservoirs and uncover its influencing factors. For this purpose, we selected the Daning-Jixian area, a region in China with relatively advanced development of deep coalbed methane, as a case study. It established a prediction model for adsorbed gas and free gas content in deep coal reservoirs through a series of experimental tests, encompassing gas content, coal quality, isothermal adsorption, and nuclear magnetic resonance. The model sheds light on the impact of coal-rock characteristics, coal quality attributes, and pore characteristics on adsorbed gas and free gas content. The results show that adsorbed gas dominates in deep coal reservoirs with a high metamorphic degree and that the average proportion of adsorbed gas under reservoir burial depth is 80.15%. At a depth of approximately 1800~2000 m, a turning point is observed where adsorbed gas content begins to decline. Beyond this depth range, the detrimental effect of temperature on coalbed methane content surpasses the beneficial impact of pressure. Coal quality characteristics play a major role in controlling adsorbed gas content, and an increase in water content and ash yield significantly reduces the adsorption performance of coal reservoirs. The content of free gas increases with the increase in burial depth, with its controlling factors primarily being confining pressure and porosity. The increase in the proportion of micropores in the pores of deep coal reservoirs has an adverse effect on the content of free gas. The proportion of adsorbed gas in deep coal reservoirs gradually decreases with the increase in burial depth, while the proportion of free gas gradually rises with the increase in burial depth. The development potential of free gas cannot be overlooked in the exploration and development of deep coalbed methane.

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“…Coalbed methane (CBM) is an efficient, clean, and high-quality unconventional natural gas source. , The development of CBM could not only improve the security of coal mine production but also optimize the structure of energy consumption and is more conducive to the reduction of carbon emission which could promote the achievement of carbon peaking and carbon neutrality. , The CBM resource within a burial depth of less than 2000 m in China accounts for 30.05 × 10 12 m 3 , while 18.47 × 10 12 m 3 in the depth of 2000–3000 m. − After the exploration and development of CBM in recent decades, two industrial bases of CBM were gradually formed in China (i.e., the southern part of Qingshui Basin and the eastern margin of Ordos Basin). − By the end of 2023, more than 20,000 CBM wells had been completed in China, and CBM production reached 117.7 × 10 8 m 3 per year. The rapid development of the CBM industry requires the support of advanced theory and technology. , …”

Section: Introductionmentioning

confidence: 99%

“… 3 , 4 The CBM resource within a burial depth of less than 2000 m in China accounts for 30.05 × 10 12 m 3 , while 18.47 × 10 12 m 3 in the depth of 2000–3000 m. 5 − 8 After the exploration and development of CBM in recent decades, two industrial bases of CBM were gradually formed in China (i.e., the southern part of Qingshui Basin and the eastern margin of Ordos Basin). 9 − 13 By the end of 2023, more than 20,000 CBM wells had been completed in China, and CBM production reached 117.7 × 10 8 m 3 per year. The rapid development of the CBM industry requires the support of advanced theory and technology.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Favorable Area for Coalbed Methane Development Based on Local Variable Weight Theory

Jin,

Yan,

Deng

et al. 2024

ACS Omega

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The evaluation of a favorable area is crucial for the exploration and exploitation of coalbed methane (CBM) resources. In traditional evaluation methods, the weight of controlling factors for the evaluation of favorable area is often obtained from different models and calculation methods, and the constant weight is commonly used in the entire target area. The influence of the index value of controlling factors and the combination state of these values on the weight is consistently overlooked during the evaluation process. In view of this phenomenon, a new evaluation method based on variable weight theory was introduced to enhance the accuracy of the result from evaluation (i.e., favorable area for CBM development) in this paper. Based on the raw data of controlling factors, the evaluation area was divided into a finite number of regular grids; each grid could be seen as an evaluation unit, and different attribute values were assigned to them. The constant weights are determined by the analytic hierarchy process (AHP), while the variable weight of controlling factors in each unit was calculated by a partitioned variable weight model (VWM) which constructed based on variable weight theory. Finally, the VWM for the evaluation of favorable area was constructed and applied in the Weibei CBM field. The influence of variability in index values on the weight was taken into consideration in this model, which can complement the disadvantage of the constant weight model (CWM). The accuracy of the result from the evaluation of favorable areas for CBM development could be improved by using this VWM, which provides a reasonable idea and method for the selection of target areas in CBM fields.

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Critical tectonic events and their geological controls on deep buried coalbed methane accumulation in Daning-Jixian Block, eastern Ordos Basin

Cited by 7 publications

References 20 publications

Full-Scale Pore and Microfracture Characterization of Deep Coal Reservoirs: A Case Study of the Benxi Formation Coal in the Daning–Jixian Block, China

Full-Scale Pore and Microfracture Characterization of Deep Coal Reservoirs: A Case Study of the Benxi Formation Coal in the Daning–Jixian Block, China

Quantitative Prediction of Deep Coalbed Methane Content in Daning-Jixian Block, Ordos Basin, China

Evaluation of Favorable Area for Coalbed Methane Development Based on Local Variable Weight Theory

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