四川盆地大安区块深层煤岩气储层特征及勘探潜力  

Reservoir characteristics and exploration potential of deep CBM in the Da'an Block,Sichuan Basin

作　　者：王高成[1,2] 田文广 章超[2] 姜振学 牛伟 田禾丰[2] 顾小敏 WANG Gaocheng;TIAN Wenguang;ZHANG Chao;JIANG Zhenxue;NIU Wei;TIAN Hefeng;GU Xiaomin(China University of Petroleum-Beijing,Beijing 102249,China;PetroChina Zhejiang Oilfield Company,Hangzhou,Zhejiang 310000,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;CNPC Key Laboratory of Coal-rock Gas,Langfang,Hebei 065007,China)

机构地区：[1]中国石油大学(北京) [2]中国石油浙江油田公司 [3]中国石油勘探开发研究院 [4]中国石油集团煤岩气重点实验室

出　　处：《天然气工业》2025年第3期68-81,共14页Natural Gas Industry

基　　金：中国石油天然气股份有限公司科技项目“深地煤岩气成藏理论与效益开发技术研究”(编号:2023ZZ18YJ01);中国石油天然气股份有限公司科学研究与技术开发项目“煤岩气富集规律与开发机理研究”(编号:2024DJ23)。

摘　　要：近期,四川盆地深层煤岩气测试获得高产工业气流,取得煤岩气勘探重大突破,展示出良好的勘探开发前景。为了深入探索该盆地大安区块龙潭组深层煤岩气的勘探潜力,系统开展了该区块龙潭组主力煤层煤岩煤质、储层物性和含气性测试分析,明确了深层煤储层微观孔隙结构等对煤岩气赋存的影响,初步讨论了深层煤岩气的勘探潜力。研究结果表明:(1)研究区龙潭组煤层埋深为2000~3500m,龙潭组19号煤层是主力煤层,其煤岩最大镜质体反射率为2.36%~2.89%,镜质组含量为48.4%~78.26%,灰分产率为10.86%~40.57%,煤体结构以原生结构为主;(2)煤岩孔隙结构非均质性强,有机质孔发育,以微孔发育为主,微孔的平均孔体积和平均比表面积占比分别为76.87%和98.28%;(3)煤岩具备较高的吸附能力,平均兰氏体积为23.28 m^(3)/t,平均兰氏压力为2.29 MPa,储层原位平均理论吸附量为18.68 m^(3)/t,实测平均含气量为21.76m^(3)/t,平均游离气占比13.47%。结论认为:(1)研究区煤岩微孔为煤岩气吸附提供点位,吸附气量随微孔发育呈现增大的趋势;(2)深埋藏条件下,优质煤储层为游离气的富集提供了良好的赋存空间,使该区深层煤岩气具备“高含气、富含游离气”的赋存特征;(3)大安地区龙潭组煤岩气资源量约0.34×10^(12)m^(3),勘探开发潜力巨大。The high-yield industrial gas flow recently obtained during deep coal-rock gas testing in the Sichuan Basin marks the great breakthrough of coal-rock gas exploration,and reveals the promising prospect of coal-rock gas exploration and development.To deeply evaluate the exploration potential of the Longtan Formation deep coal-rock gas in the Da'an block of the Sichuan Basin,this paper systematically tests and analyzes the coal quality,reservoir properties,and gas content of the principal coal seams of Longtan Formation in this block,clarifies the influence of microscopic pore structures in deep coal reservoir on the occurrence of coal-rock gas,and preliminarily discusses the exploration potential of deep coal-rock gas.The following results are obtained.First,the Longtan Formation coal seam in the study area is at the burial depth ranging from 2000 m to 3500 m.The No.19 coal seam of Longtan Formation is the principal coal seam,with maximum vitrinite reflectance of 2.36%-2.89%,vitrinite content of 48.4%-78.26%,ash yield of 10.86%-40.57%,and it is dominated by primary coal structures.Second,the pore structures in the coal rocks are of strong heterogeneity,with developed organic pores dominated by micropores(76.87%pore volume and 98.28%specific surface area).Third,coal rocks have strong adsorptivity with average Langmuir volume of 23.28 m^(3)/t,average Langmuir pressure of 2.29 MPa,in-situ theoretical adsorbed gas content of 18.68 m^(3)/t,average measured gas content of 21.76 m^(3)/t and average free gas proportion of 13.47%.In conclusion,the micropores in coal rocks in the study area provide sites for coal-rock gas adsorption,with the volume of adsorbed gas positively correlated to the development of micropores.What's more,under great burial depth,high-quality coal reservoirs provide good space for the enrichment of free gas,resulting in the occurrence characteristics of deep coal-rock gas,i.e.,"high total gas content with enriched free 12 gas".Furthermore,the volume of the Longtan Formation coal-rock gas resources in

关 键 词：四川盆地 上二叠统龙潭组 深层煤岩气 储层物性 含气性 吸附性 勘探潜力 

分 类 号：TE122.2[石油与天然气工程—油气勘探]