School of Energy Resources, China University of Geosciences (Beijing)
Research Institute of Exploration and Development, PetroChina Huabei Oilfield Company
Shanxi Coal Geology Surveys Research Institute

温度是影响深部煤储层含气性的重要因素，继而影响深部煤层气的开发效果。因此，明确煤储层地温条件及其对深部煤储层含气性的影响是系统认识深部煤层气富集特征及生产规律的关键。宁武盆地太原组9号煤层埋深大于1 000 m的面积占比超过90%，盆地腹部煤层埋深基本大于1 500 m，最大埋深超过2 500 m，属于典型的深部煤层气。以宁武南区块为例，基于井温测井数据、实验测试数据、录井资料及试井资料，确定宁武南煤储层地温场特征及其对含气性的影响效应。结果显示，宁武南区块9号煤储层温度为15.5~40.1℃，与煤层埋深具有显著的正相关性，地温梯度为1.27~1.95℃/hm，平均为1.52℃/hm，显示出低地温场特征。研究区煤储层含气饱和度为40.1%~93.7%，平均为71.7%，显示出深部煤储层低含气饱和度的特征。随着埋藏深度的增加，较低的地温梯度使得研究区煤储层温度增加缓慢，导致在相似埋深下，温度对研究区深部煤储层吸附能力的负效应显著低于大宁−吉县、临兴等深部煤层气区块，使得研究区煤储层吸附气向游离气的转换深度加深且转换比例降低。低地温条件是影响研究区深部煤层含气性的重要因素之一，继而影响其可开采程度。在深部煤层气的勘探开发中应重视煤储层地温条件的研究。

Temperature acts as an important factor affecting the gas-bearing properties of deep coal reservoirs, further affecting the development performance of deep coalbed methane (CBM). Therefore, ascertaining the geothermal conditions of coal reservoirs and their effects on the gas-bearing properties of deep coal reservoirs is critical to the systemic understanding of the enrichment characteristics and production patterns of deep CBM. For coal seam No.9 in the Taiyuan Formation within the Ningwu Basin, over 90% of the area has burial depths exceeding 1000 m. In the hinterland of the basin, coal seams generally exhibit burial depths greater than 1500 m, with a maximum exceeding 2500 m. These findings suggest typical deep CBM. Based on the log data, experiments data, and well test data, this study determined the geothermal field characteristics of the coal reservoirs in the Ningwunan block and their effects on the gas-bearing properties. The results show that coal seam No.9 in the Ningwunan block exhibits reservoir temperature ranging between 15.5℃ and 40.1℃ and there is a significant positive correlation between the reservoir temperature and the burial depth. The coal reservoirs have geothermal gradients ranging from 1.27 to 1.95℃/hm, with an average of 1.52℃/hm, indicating the characteristics of low geothermal fields. These reservoirs demonstrate gas saturation ranging from 40.1% to 93.7%, with an average of 71.7%, suggesting low gas saturation of the deep coal reservoirs. With an increase in the burial depth, the coal reservoir temperature increases slowly due to the low geothermal gradients. This results in significantly reduced negative effects of temperature on the adsorption capacity of deep coal reservoirs in the study area compared to deep CBM-bearing blocks at similar burial depths, such as Daning-Jixian and Linxing. Accordingly, the depth at which adsorbed gas transitions into free gas increases for coal reservoirs in the study area, with the transition ratio between both types of gases decreasing. Low temperature serves as an important factor affecting the gas-bearing properties of deep coal reservoirs in the study area, further influencing their recoverable degree. Therefore, the geothermal conditions of coal reservoirs should be highlighted in the exploration and recovery of deep CBM.

国家自然科学基金项目(42272197，U1910205)

郗兆栋，唐书恒，刘忠，等. 宁武盆地深部煤储层地温场特征及其对含气性的影响[J]. 煤田地质与勘探，2024，52(2)：92−101.

XI Zhaodong，TANG Shuheng，LIU Zhong，et al. Deep coal reservoirs in the Ningwu Basin: Geothermal field characteristics and their effects on gas-bearing properties[J]. Coal Geology & Exploration，2024，52(2)：92−101.