Heterogeneity and its controlling effect on coalbed methane productivity for deep coal reservoirs in the northern part of the eastern margin of the Ordos Basin

Authors

• XI Zhaodong, School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China;Shanxi Center of Technology Innovation for Coal Measure Mineral Resources Comprehensive Exploration, Taiyuan 030000, ChinaFollow
• TANG Shuheng, School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China;Shanxi Center of Technology Innovation for Coal Measure Mineral Resources Comprehensive Exploration, Taiyuan 030000, ChinaFollow
• WU Jian, China United Coalbed Methane Corp., Ltd., Beijing 100016, China
• ZHANG Songhang, School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China;Shanxi Center of Technology Innovation for Coal Measure Mineral Resources Comprehensive Exploration, Taiyuan 030000, China
• ZHAO Hang, School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China
• CHEN Jiang, Shanxi Provincial Mineral Resources Survey and Monitoring Center, Taiyuan 030024, China
• LI Yanfei, Shanxi Provincial Mineral Resources Survey and Monitoring Center, Taiyuan 030024, China

Abstract

Objective With the continuous advancement in the exploration and exploitation of coalbed methane (CBM), the focus of research and practices is gradually shifting from shallow to deep parts. Deep CBM, an important unconventional natural gas resource, has become a strategic replacement to ensure energy security and prompt industrial development in China. However, deep coal reservoirs exhibit strong heterogeneities, posing a core geological challenge to their efficient exploration and development. Methods This study investigated the deep No. 8 coal seam in the northern part of the eastern margin of the Ordos Basin. By integrating multiple technical methods, including geostatistics, spatial interpolation, substantial core tests, and numerical simulation, this study systematically examined the multi-scale heterogeneities of reservoirs in the No. 8 coal seam in the lateral and vertical directions. Furthermore, the controlling effects of reservoir heterogeneities on CBM productivity were quantitatively assessed. Results and Conclusions The results indicate that deep coal reservoirs in the northern part of the eastern margin of the Ordos Basin exhibit a representative heterogeneous mode characterized by a homogeneous geological background but differential key parameters. The burial depth, vitrinite reflectance (R_max), and vitrinite content of the reservoirs show coefficients of variation (CVs) of less than 0.15, suggesting the high stability of the regional tectonic setting, thermal evolution history, and coal-forming environments. In contrast, the Langmuir volume, gas content, and adsorbed gas saturation of the reservoirs exhibit CVs ranging from 0.27 to 0.33, implying moderate heterogeneities. Furthermore, the spatial differentiations of these parameters are governed by the coupling effects of local factors. Based on these findings, three CBM enrichment patterns were identified in the study area. Specifically, the southeastern part exhibits gas generation-dominated CBM enrichment, which is driven by thermal anomalies of concealed rock masses and features high R_max and gas content. The southwestern part manifests a CBM enrichment pattern characterized by great burial depth and high saturation. This enrichment pattern can be attributed to both weak adsorption effects under high temperatures due to deep burial and favorable preservation conditions, which jointly contribute to the formation of a free gas enrichment area with high adsorbed gas saturation. The northern part displays low hydrocarbon generation and weak preservation conditions, identified as an area with poor gas-bearing properties. Based on two representative wells, this study revealed the binary control mechanisms behind the vertical heterogeneity of gas-bearing properties in the No. 8 coal seam. Under the geological setting of poor preservation conditions, the intralayer sealing effect predominates, with gas-bearing properties tending to be higher in the middle part and lower in the upper and lower parts vertically. In this case, sweet spot intervals are situated in the middle part of the coal seam. In areas with favorable preservation conditions, the vertical distribution of gas-bearing properties is primarily governed by the static differentiation of original coal-forming materials. Numerical simulations corroborate that the heterogeneous distributions of vertical gas-bearing properties exert significant impacts on CBM productivity. The 10-year cumulative gas production of the scheme with precise perforation in a sweet spot interval was 4.1 times higher than that of the scheme with perforation arranged in an interval with poor gas-bearing properties. Integrating research on the vertical heterogeneity of coal reservoirs into the precise positioning of sweet spot intervals and the optimization of perforation schemes is key to the fine-scale and efficient exploitation of deep CBM. The results of this study are of great significance for gaining deep insights into the enrichment patterns of deep CBM and for guiding the exploration and exploitation practices of deep CBM under similar geological conditions.

Keywords

eastern margin of the Ordos Basin, deep coalbed methane (CBM), gas-bearing properties, accumulation, productivity

DOI

10.12363/issn.1001-1986.25.11.0870

Recommended Citation

XI Zhaodong, TANG Shuheng, WU Jian, et al. (2026) "Heterogeneity and its controlling effect on coalbed methane productivity for deep coal reservoirs in the northern part of the eastern margin of the Ordos Basin," Coal Geology & Exploration: Vol. 54: Iss. 7, Article 9.
DOI: 10.12363/issn.1001-1986.25.11.0870
Available at: https://cge.researchcommons.org/journal/vol54/iss7/9

Reference

[1] 叶建平. 中国煤层气勘探开发及其科技进步历程回顾与思考[J]. 煤田地质与勘探,2025,53(1):114−127 YE Jianping. China’s CBM exploration and production and associated technological advancements:A review and reflections[J]. Coal Geology & Exploration,2025,53(1):114−127

[2] 秦勇,申建,李小刚. 中国煤层气资源控制程度及可靠性分析[J]. 天然气工业,2022,42(6):19−32 QIN Yong,SHEN Jian,LI Xiaogang. Control degree and reliability of CBM resources in China[J]. Natural Gas Industry,2022,42(6):19−32

[3] 杨兆彪,卢本举,周国晓,等. 深部煤层气地质特殊性与释放产出规律[J]. 石油学报,2025,46(8):1464−1476 YANG Zhaobiao,LU Benju,ZHOU Guoxiao,et al. Geological particularities and desorption–production patterns of deep coalbed methane[J]. Acta Petrolei Sinica,2025,46(8):1464−1476

[4] 徐凤银,侯伟,熊先钺,等. 中国煤层气产业现状与发展战略[J]. 石油勘探与开发,2023,50(4):669−682 XU Fengyin,HOU Wei,XIONG Xianyue,et al. The status and development strategy of coalbed methane industry in China[J]. Petroleum Exploration and Development,2023,50(4):669−682

[5] 张君峰,李国欣,贾承造,等. 煤系全油气系统中天然气类型与煤岩气分类研究[J]. 石油勘探与开发,2025,52(4):792−803 ZHANG Junfeng,LI Guoxin,JIA Chengzao,et al. Natural gas types and coal rock gas classification in the whole petroleum system of coal measures[J]. Petroleum Exploration and Development,2025,52(4):792−803

[6] 李国欣,张斌,张君峰,等. 中国深层煤岩气勘探开发重大基础科学问题与研究方向[J]. 石油学报,2025,46(6):1025−1036 LI Guoxin,ZHANG Bin,ZHANG Junfeng,et al. Major basic scientific issues and research directions for exploration and development of deep coal–rock gas in China[J]. Acta Petrolei Sinica,2025,46(6):1025−1036

[7] 李安,蔡益栋,王子豪,等. 基于机器学习测井反演的煤体结构评价:以鄂尔多斯盆地榆林地区本溪组8号煤为例[J]. 地质科技通报,2025,44(4):2−15 LI An,CAI Yidong,WANG Zihao,et al. Evaluation of coal structure based on machine learning logging inversion:A case from No. 8 coal of Benxi Formation in Yulin area of Ordos Basin[J]. Bulletin of Geological Science and Technology,2025,44(4):2−15

[8] 闫霞,熊先钺,徐凤银,等. 深部煤岩储层地质力学影响机制及控制因素:以鄂尔多斯盆地大吉区块为例[J]. 煤炭学报,2025,50(5):2550−2566 YAN Xia,XIONG Xianyue,XU Fengyin,et al. Deep coal geomechanical influence mechanism and its control factors of Daji Block in Ordos Basin[J]. Journal of China Coal Society,2025,50(5):2550−2566

[9] 郭涛,周亚彤,金晓波,等. 中国南方煤层气主要地质特点、勘探开发进展及策略[J]. 煤田地质与勘探,2025,53(3):44−53 GUO Tao,ZHOU Yatong,JIN Xiaobo,et al. Primary geological characteristics,advances in exploration and production,and strategies of coalbed methane in South China[J]. Coal Geology & Exploration,2025,53(3):44−53

[10] 刘大锰,贾奇锋,蔡益栋. 中国煤层气储层地质与表征技术研究进展[J]. 煤炭科学技术,2022,50(1):196−203 LIU Dameng,JIA Qifeng,CAI Yidong. Research progress on coalbed methane reservoir geology and characterization technology in China[J]. Coal Science and Technology,2022,50(1):196−203

[11] OUYANG Zheyuan,WANG Haichao,SUN Bin,et al. Quantitative prediction of deep coalbed methane content in Daning–Jixian Block,Ordos Basin,China[J]. Processes,2023,11(11):3093.

[12] GONG Fei,CHENG Jiwei,WANG Guowei,et al. The effect of lamination on elastic anisotropy of primary coals under confining pressure:Experiment and theoretical modelling[J]. Geophysical Prospecting,2025,73(4):1228−1242.

[13] YANG Xiongxiong,TANG Shuheng,XI Zhaodong,et al. Dynamic evolution and differential enrichment of deep coalbed methane:A case study in Qinshui Basin[J]. International Journal of Coal Geology,2025,299:104696.

[14] 牛小兵,张辉,王怀厂,等. 鄂尔多斯盆地中、东部石炭系本溪组煤储层纵向非均质性特征及成因:以M172井为例[J]. 石油与天然气地质,2024,45(6):1577−1589 NIU Xiaobing,ZHANG Hui,WANG Huaichang,et al. Characteristics and genesis of vertical heterogeneity in a coal seam of the Carboniferous Benxi Formation,eastern Ordos Basin:A case study of well M172[J]. Oil & Gas Geology,2024,45(6):1577−1589

[15] 闫霞,熊先钺,李曙光,等. 深层煤岩气水平井各段产出贡献及其主控因素:以鄂尔多斯盆地东缘大宁–吉县区块为例[J]. 天然气工业,2024,44(10):80−92 YAN Xia,XIONG Xianyue,LI Shuguang,et al. Production contributions of deep CBM horizontal well sections and their controlling factors:A case study of Daning–Jixian area,eastern Ordos Basin[J]. Natural Gas Industry,2024,44(10):80−92

[16] 邵龙义,党星宇,高祥宇,等. 厚煤层成因机制:天文周期控制的多期次泥炭沼泽叠加模式[J]. 煤炭科学技术,2022,50(1):186−195 SHAO Longyi,DANG Xingyu,GAO Xiangyu,et al. Genetic mechanism of thick coal seams:Astronomical–forcing superimposed multi–staged swamp model[J]. Coal Science and Technology,2022,50(1):186−195

[17] WANG Shuai,SHAO Longyi,WANG Dongdong,et al. Controls on accumulation of anomalously thick coals:Implications for sequence stratigraphic analysis[J]. Sedimentology,2020,67(2):991−1013.

[18] 郗兆栋,唐书恒,杨文府,等. 煤层自封闭性对深层煤岩气的富集与改造意义[J]. 天然气工业,2024,44(10):105−112 XI Zhaodong,TANG Shuheng,YANG Wenfu,et al. Implications of coal reservoir self–sealing for the enrichment and stimulation of deep coal–rock gas[J]. Natural Gas Industry,2024,44(10):105−112

[19] 闫霞,徐凤银,张雷,等. 微构造对煤层气的控藏机理与控产模式[J]. 煤炭学报,2022,47(2):893−905 YAN Xia,XU Fengyin,ZHANG Lei,et al. Reservoir–controlling mechanism and production–controlling patterns of microstructure to coalbed methane[J]. Journal of China Coal Society,2022,47(2):893−905

[20] 周立宏,闫霞,熊先钺,等. 深部煤层气超临界状态下赋存特征及分配规律[J]. 煤炭科学技术,2025,53(3):73−90 ZHOU Lihong,YAN Xia,XIONG Xianyue,et al. Characteristics of occurrence and distribution rule of deep coalbed methane in supercritical state[J]. Coal Science and Technology,2025,53(3):73−90

[21] 周立宏,李勇,丁蓉,等. 深煤层富气层段的超越效应及其表征[J]. 煤田地质与勘探,2025,53(12):146−156 ZHOU Lihong,LI Yong,DING Rong,et al. Supersaturation effect and its characterization in gas–rich intervals of deep coal seams[J]. Coal Geology & Exploration,2025,53(12):146−156

[22] 魏虎,林进,王香增,等. 鄂尔多斯盆地东南缘深部8#煤储层地质特征及含气性主控因素分析[J]. 现代地质,2025,39(5):1316−1331 WEI Hu,LIN Jin,WANG Xiangzeng,et al. Analysis of geological characteristics and main controlling factors of gas–bearing capacity in the deep No. 8 coal seam,southeastern margin of the Ordos Basin[J]. Geoscience,2025,39(5):1316−1331

[23] 米洪刚,吴见,彭文春,等. 神府区块深部煤储层力学特性及裂缝扩展机制[J]. 煤田地质与勘探,2024,52(8):32−43 MI Honggang,WU Jian,PENG Wenchun,et al. Mechanical characteristics and fracture propagation mechanism of deep coal reservoirs in the Shenfu Block[J]. Coal Geology & Exploration,2024,52(8):32−43

[24] 王舵,刘之的,王成旺,等. 鄂尔多斯盆地DJ区块深部煤储层地质–工程甜点测井评价技术[J]. 石油与天然气地质,2024,45(6):1772−1788 WANG Duo,LIU Zhidi,WANG Chengwang,et al. Logging–based evaluation for geological–engineering sweet spots in deep coal reservoirs of the DJ Block,Ordos Basin[J]. Oil & Gas Geology,2024,45(6):1772−1788

[25] 范立勇,陈跃,王怀厂,等. 鄂尔多斯盆地中东部深部煤储层孔隙多尺度联合表征及多重分形特征[J]. 现代地质,2026,40(1):113−127 FAN Liyong,CHEN Yue,WANG Huaichang,et al. Combined Multi-Scale Characterization and Multifractal Characteristics of Deep Coal Reservoir Pores in the Central-Eastern Ordos Basin[J]. Geoscience,2026,40(1):113−127

[26] 许浩,汤达祯,陶树,等. 深、浅部煤层气地质条件差异性及其形成机制[J]. 煤田地质与勘探,2024,52(2):33−39 XU Hao,TANG Dazhen,TAO Shu,et al. Differences in geological conditions of deep and shallow coalbed methane and their formation mechanisms[J]. Coal Geology & Exploration,2024,52(2):33−39

[27] 刘旭东,桑树勋,周效志,等. 基于煤储层三维非均质地质模型的CO2–ECBM数值模拟研究[J]. 煤炭学报,2023,48(7):2773−2790 LIU Xudong,SANG Shuxun,ZHOU Xiaozhi,et al. Numerical simulation of CO2–ECBM based on 3D heterogeneous geological model[J]. Journal of China Coal Society,2023,48(7):2773−2790

[28] 龚飞,彭苏萍,程绩伟,等. 深部煤层气储层各向异性岩石物理建模及应用[J]. 煤炭学报,2025,50(增刊1):476−491 GONG Fei,PENG Suping,CHENG Jiwei,et al. Anisotropic rock physics modeling and its application for deep coalbed methane reservoirs[J]. Journal of China Coal Society,2025,50(Sup.1):476−491

[29] 徐长贵,季洪泉,王存武,等. 鄂尔多斯盆地东缘临兴–神府区块深部煤层气富集规律与勘探对策[J]. 煤田地质与勘探,2024,52(8):1−11 XU Changgui,JI Hongquan,WANG Cunwu,et al. Enrichment patterns and exploration countermeasures of deep coalbed methane in the Linxing–Shenfu Block on the eastern margin of the Ordos Basin[J]. Coal Geology & Exploration,2024,52(8):1−11

[30] 蔡益栋,高国森,刘大锰,等. 鄂尔多斯盆地东缘临兴中区煤系气富集地质条件及成藏模式[J]. 天然气工业,2022,42(11):25−36 CAI Yidong,GAO Guosen,LIU Dameng,et al. Geological conditions for coal measure gas enrichment and accumulation models in Linxingzhong Block along the eastern margin of the Ordos Basin[J]. Natural Gas Industry,2022,42(11):25−36

[31] 唐书恒,郗兆栋,张松航,等. 深部煤层气赋存相态与含气性演化[J]. 煤炭科学技术,2025,53(3):91−100 TANG Shuheng,XI Zhaodong,ZHANG Songhang,et al. Occurrence phase and gas–bearing evolution of deep coalbed methane[J]. Coal Science and Technology,2025,53(3):91−100

[32] 孙立春,刘佳,田永净,等. 神府区块深部煤层气开发早期实践认识与攻关方向[J]. 中国海上油气,2025,37(1):116−128 SUN Lichun,LIU Jia,TIAN Yongjing,et al. Early practical experience and key research directions for deep coalbed methane development in the Shenfu Block[J]. China Offshore Oil and Gas,2025,37(1):116−128

[33] 徐凤银,王成旺,熊先钺,等. 鄂尔多斯盆地东缘深部煤层气成藏演化规律与勘探开发实践[J]. 石油学报,2023,44(11):1764−1780 XU Fengyin,WANG Chengwang,XIONG Xianyue,et al. Evolution law of deep coalbed methane reservoir formation and exploration and development practice in the eastern margin of Ordos Basin[J]. Acta Petrolei Sinica,2023,44(11):1764−1780

[34] 郗兆栋,唐书恒,段利江,等. 深部煤层游离气富集控制因素与勘探开发意义[J]. 中国矿业大学学报,2026,55(1):180−192 XI Zhaodong,TANG Shuheng,DUAN Lijiang,et al. Controlling factors of free gas enrichment in deep coal seams and their implications for exploration and development[J]. Journal of China University of Mining & Technology,2026,55(1):180−192

[35] WANG Tao,TIAN Fenghua,DENG Ze,et al. The characteristic development of micropores in deep coal and its relationship with adsorption capacity on the eastern margin of the Ordos Basin,China[J]. Minerals,2023,13(3):302.