鄂尔多斯盆地临兴—神府地区深部煤储层储渗空间发育特征及产水能力评价

Storage and permeation space development characteristics and water production capacity evaluation of deep coal reservoirs in Linxing-Shenfu area of Ordos Basin

王金伟 许浩 刘一楠 张兵 徐延勇 刘丁 宗鹏 王亚娟 宋雪静

WANG Jinwei XU Hao LIU Yinan ZHANG Bing XU Yanyong LIU Ding ZONG Peng WANG Yajuan SONG Xuejing

1. 中国地质大学(北京) 能源学院, 北京 100083; 2. 国家煤层气工程中心 煤储层物性实验室, 北京 100083; 3. 山西省煤系矿产综合勘查技术创新中心, 太原 030006; 4. 中联煤层气有限责任公司, 北京 100016

1. School of Energy Resources, University of Geosciences (Beijing), Beijing 100083, China; 2. Coal Reservoir Laboratory, National Engineering Research Center of Coalbed Methane Development & Utilization, Beijing 100083, China; 3. Center of Technology Innovation for Coal Measure Mineral Resources Comprehensive Explorationof Shanxi Province, Taiyuan, Shanxi 030006, China; 4. China United Coalbed Methane Co., Ltd., Beijing 100016, China

鄂尔多斯盆地临兴—神府地区是我国深部煤层气开发重点区块之一，实际生产中不同区域煤层气井产水量差异显著，影响了深部煤层气的高效开发。通过高压压汞、低温CO2吸附、低温N2吸附、CT扫描等实验，对临兴—神府地区8#+9#煤层的煤岩样品进行了全尺度的联测表征，查明了研究区储渗空间发育特征。通过赋水模拟实验模拟计算了煤岩储水能力，通过数值模拟预测深部储层产水量，明确了研究区深部煤储层的产水能力，并进一步结合煤层气井产水数据评价了煤层水的来源。研究表明，临兴—神府地区深部煤储层整体上微孔和宏孔及裂隙比较发育，介孔发育相对较差。随变质程度升高，总孔体积先减后增，深部煤岩原始含水性急剧下降，储水能力先减后增，光亮煤在储水能力上有较大优势。研究区低镜质体反射率(Ro)煤岩日均产水量预测为12.81~26.01 m3，中Ro煤岩为1.82~7.22 m3，高Ro煤岩为1.90~8.22 m3。煤层气井实际日产水量超出该范围即为受外源水补给影响，低于该范围即为煤层自产。深部煤储层原始含水性较差，且储水能力有限，尤其在高Ro段，即使储层在完全饱和水的条件下，其产水量也应保持较低水平，持续高产水必定伴随大量的外源输入。

The Linxing-Shenfu area in the Ordos Basin is one of the key areas for deep coalbed methane (CBM) development in China. However, significant variations in water production among CBM wells in different regions have hindered the efficient development of deep CBM. This study conducted multi-scale characterizations of coal samples from the 8#+9# coal seams in the Linxing-Shenfu area using high-pressure mercury intrusion porosimetry, low-temperature CO2 adsorption, low-temperature N2 adsorption, and CT scanning experiments. These methods revealed the development characteristics of the storage and permeability space in the study area. Water saturation simulation experiments were conducted to estimate the water storage capacity of coal samples, and numerical simulations were used to predict the water production capacity of deep reservoirs, providing a clear understanding of the water production capacity of deep coal reservoirs in the study area. Combined with actual water production data from CBM wells, the sources of coal seam water were further evaluated. The results show that deep coal reservoirs in the Linxing-Shenfu area exhibit well-developed micropores, macropores, and fractures, with relatively underdeveloped mesopores. As coal rank increases, the total pore volume first decreases and then increases. The original water content of deep coal samples declines sharply, while the water storage capacity first decreases and then increases, with bright coal showing a greater advantage in water storage capacity. The predicted daily water production ranges for low-vitrinite-reflectance (Ro) coal reservoirs in the study area are 12.81 to 26.01 m3, for medium-Ro coal reservoirs 1.82 to 7.22 m3, and for high-Ro coal reservoirs 1.90 to 8.22 m3. Actual water production exceeding these ranges indicates the influence from external water input, while production below these ranges indicates self-sourced water from the coal seams. Deep coal reservoirs have poor original water content and limited water storage capacity, especially in high-Ro coal reservoirs. Even when these reservoirs are fully saturated, water production remains low. Sustained high water output must involve substantial external water input.

国家自然科学基金项目(42172188)资助。

https://doi.org/10.11781/sysydz2025010054