煤田地质与勘探2024，Vol.52Issue(2)：92-101,10.DOI:10.12363/issn.1001-1986.23.07.0408
宁武盆地深部煤储层地温场特征及其对含气性的影响
Deep coal reservoirs in the Ningwu Basin:Geothermal field characteristics and their effects on gas-bearing properties
摘要
Abstract
Temperature acts as an important factor affecting the gas-bearing properties of deep coal reservoirs,further af-fecting the development performance of deep coalbed methane(CBM).Therefore,ascertaining the geothermal condi-tions 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 Taiy-uan Formation within the Ningwu Basin,over 90%of the area has burial depths exceeding 1 000 m.In the hinterland of the basin,coal seams generally exhibit burial depths greater than 1 500 m,with a maximum exceeding 2 500 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 prop-erties.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,indicat-ing 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 buri-al depth,the coal reservoir temperature increases slowly due to the low geothermal gradients.This results in signific-antly reduced negative effects of temperature on the adsorption capacity of deep coal reservoirs in the study area com-pared 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 proper-ties of deep coal reservoirs in the study area,further influencing their recoverable degree.Therefore,the geothermal con-ditions of coal reservoirs should be highlighted in the exploration and recovery of deep CBM.关键词
宁武盆地/深部煤层气/地温梯度/地温场/含气性Key words
Ningwu Basin/deep coalbed methane/geothermal gradient/geothermal field/gas-bearing properties分类
天文与地球科学引用本文复制引用
郗兆栋,唐书恒,刘忠,屈晓荣,张鹏豹,苏育飞,张迁..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):92-101,10.基金项目
国家自然科学基金项目(42272197,U1910205) （42272197,U1910205）
