Research Institute of Exploration and Development, Jilin Oilfield Company
School of Energy Resources, China University of Geosciences (Beijing)
Research Institute of Petroleum Exploration & Development, PetroChina
PetroChina Bohai Drilling Downhole Operation Company

松辽盆地南部王府断陷煤层气资源量丰富，但深部煤层气勘探程度较低，在煤层气地质特征、富集成藏主控因素及有利目标优选等方面缺乏系统研究，制约了该区煤层气勘探进程。为此，在系统分析煤系地质特征的基础上，明确深部煤层气成藏主控因素，建立有利区优选指标体系，预测煤层气富集有利区。结果表明：(1) 王府断陷火石岭组宏观煤岩类型以光亮煤、半亮煤为主，具有低水分、低挥发分、低灰分的特征，镜质体最大反射率大于1.8%，孔隙率平均5.01%，CS38井计算的平均含气量为21.80 m3/t。(2) 王府断陷火石岭组火山喷发填平补齐沉积环境利于煤层发育，煤层主要发育于断陷双陡坡带之间与断陷中、东部的火山喷发的填平补齐效应形成的浅水区，形成了“填平补齐成煤模式”。此外，区内发育的大面积巨厚泥岩顶板与封闭断层使得煤层气得以富集保存。(3)王府断陷Ⅰ类有利区主要发育在断陷中部，煤层厚度大于5 m，断层断距<50 m，盖层厚度>80 m，气测全烃值>15%，具有较大勘探开发潜力；Ⅱ、Ⅲ类有利区主要发育在断陷的北部和南部，煤层厚度一般<5 m，盖层厚度<80 m，气测全烃值<15%，断层封闭性弱或不封闭，盖层厚度差异大，勘探开发风险较大。

The Wangfu fault depression in the southern Songliao Basin is rich in coalbed methane (CBM) resources. However, CBM exploration in this area has been restricted by the low-level exploration of deep CBM and a lack of systematic studies on the geological characteristics of CBM, primary factors controlling CBM enrichment and accumulation, and the selection of favorable targets. Therefore, based on the systematical analysis of the geological characteristics of coal-bearing strata, this study identified the major factors controlling deep CBM accumulation, established the index system for favorable area selection, and predicted the favorable areas of CBM enrichment. The results show that: (1) Macroscopically, coals in the Huoshiling Formation in the Wangfu fault depression can be primarily categorized into bright and semi-bright coals, possessing the characteristics of low moisture, low volatile constituents, and low ash content. They exhibit vitrinite reflectance > 1.8%, average porosity of 5.01%, and average gas content of 21.80 m3/t (calculated based on well CS38). (2) The sedimentary environment, filled and leveled through volcanic eruption, of the Huoshiling Formation in the Wangfu fault depression is conducive to the formation of coal seams. Specifically, coal seams primarily occur between the double steep slope zones and in the shallow water areas of the central and eastern Wangfu fault depression, which were formed by the filling and leveling effects of volcanic eruption. In this manner, the coal formation mode featuring filling and leveling is formed. Additionally, the presence of large-area thick mudstone roofs and closed faults allow for CBM enrichment and preservation in the fault depression. (3) Class I favorable areas in the Wangfu fault depression predominantly occur in the northern and central parts of the fault depression, with coal seam thicknesses > 5m, fault throw <50 m, cover thicknesses > 80 m, and gas logging-derived total hydrocarbon values > 15%. These suggest great potential for exploration and exploitation. Classes Ⅱ and Ⅲ favorable areas are mainly found in the northern and southern parts of the fault depression, with coal seam thicknesses < 5m, cover thicknesses < 80 m, and gas logging-derived total hydrocarbon values < 15%. Weak-sealing or open faults and greatly different cover thicknesses pose risks to CBM exploration and exploration in these areas.

中国石油天然气股份有限公司攻关性应用性科技专项项目(2023ZZ18)

沈霞，公海涛，邵明礼，等. 松辽盆地南部王府断陷深部煤层气地质特征及有利区评价[J]. 煤田地质与勘探，2024，52(2)：113−121.

SHEN Xia，GONG Haitao，SHAO Mingli，et al. Geological characteristics and favorable area evaluation of deep coalbed methane in Wangfu fault depression, southern Songliao Basin[J]. Coal Geology & Exploration，2024，52(2)：113−121.