鄂尔多斯盆地上古生界煤岩气成藏地质条件及勘探方向  

Reservoir-forming geological conditions and exploration directions of Upper Paleozoic coal-rock gas in the Ordos Basin

作　　者：牛小兵[1,2] 喻健 徐旺林[3] 王康乐[1,4] 问晓勇[1,5] 孙远实[3] 张君莹 NIU Xiaobing;YU Jian;XU Wanglin;WANG Kangle;WEN Xiaoyong;SUN Yuanshi;ZHANG Junying(National Engineering Laboratory of Low-permeability Oil&Gas Exploration and Development,Xi'an,Shaanxi 710018,China;PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;Exploration and Development Research Institute,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;Oil and Gas Technology Research Institute,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China)

机构地区：[1]低渗透油气田勘探开发国家工程实验室,陕西省西安市710018 [2]中国石油长庆油田公司 [3]中国石油勘探开发研究院,北京市100083 [4]中国石油长庆油田公司勘探开发研究院 [5]中国石油长庆油田公司油气工艺研究院

出　　处：《天然气工业》2024年第10期33-50,共18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:2023ZZ18YJ03);中国石油长庆油田公司关键核心技术攻关项目“鄂尔多斯盆地深层煤岩气赋存机理、富集规律及有效提产关键技术攻关”(编号:2023DZZ01)。

摘　　要：为了进一步提高鄂尔多斯盆地煤岩气勘探开发效益,综合钻井、录井和分析测试等资料,从盆地尺度上系统地研究了上古生界煤系地层聚煤环境、煤质特征、储层物性和含气性,分析了盆地煤岩气成藏条件,总结了煤岩气勘探开发关键技术,评估了盆地煤岩气资源,并指出了煤岩气的勘探方向。研究结果表明:①盆地石炭纪本溪期海陆交互相沉积与二叠纪山西期陆相三角洲沉积发育形成广泛分布的煤岩,热演化程度较高,镜质组含量高,生烃规模大。②盆地深层煤质优良,以光亮煤和半亮煤为主,煤体结构良好,以原生结构煤为主,固定碳含量高,挥发分和灰分产率低。③煤岩储层发育储集空间包括气孔、植物组织孔和无机矿物质孔,割理和裂隙发育,平均孔隙度为4.80%,平均渗透率为2.35 mD,属于致密储层;煤岩平均含气量为22.53 m^(3)/t,其中游离气平均含量为5.65 m^(3)/t,占总含气量的25.08%。④煤岩与上覆不同岩性形成了煤岩-泥岩、煤岩-石灰岩和煤岩-砂岩3种储盖组合,控制了游离气富集分布,提出了“源储一体、持续生烃、盖层封堵”的煤岩气成藏模式。⑤在煤岩气勘探实践中形成了地震地质综合建模、水平井钻完井、压裂改造和限压排采等一系列配套工程技术。⑥盆地本溪组8号煤岩和山西组5号煤岩埋深1500 m以深煤岩叠合总面积16.70×104 km^(2),估算煤岩气总资源量23.47×10^(12) m^(3)。其中8号煤岩分布面积10.63×104 km^(2),煤岩气资源量17.43×10^(12) m^(3);5号煤岩分布面积6.06×104 km^(2),煤岩气资源量6.04×10^(12) m^(3)。结论认为:①鄂尔多斯盆地煤岩气地质条件优越,资源潜力巨大,勘探配套技术已基本形成,煤岩气勘探开发前景良好;②神木周边、榆林周边、乌审旗周边、米脂北、佳县、绥德、吴堡、大宁-吉县等区带8号煤岩,神木-伊金霍洛旗、榆林-佳县、乌审旗北、横山-子洲等�In order to further improve the efficiency of coal-rock gas exploration and development in the Ordos Basin,this paper systematically studies the coal accumulation environment,coal quality,reservoir properties and coal-rock gas content of the Upper Paleozoic coal rock strata at the basin scale using the drilling,logging and testing data.Then,the reservoir-forming conditions of coal-rock gas in this basin are analyzed,and the key technologies for coal-rock gas exploration and development are summarized.Finally,the coal-rock gas resources in this basin are assessed,and the direction of coal-rock gas exploration is pointed out.The following results are obtained.First,the coal rocks,which are formed due to the development of Carboniferous Benxi Formation marine-continental interactive deposits and Permian Shanxi Formation continental delta deposits,are distributed widely in the Ordos Basin,and they have a high thermal evolution degree,high vitrinite content and large hydrocarbon generation scale.Second,the deep coal rocks in the Ordos Basin are of excellent quality,and they are mainly bright coal and semi-bright coal.The coal texture is good,with primary-texture coal in dominance.The fixed carbon content is high,while the volatile and ash yields are low.Third,the storage space in coal-rock gas reservoirs includes stomata,plant tissue pores and inorganic mineral pores,with cleats and fissures.The average porosity is 4.80%and the average permeability is 2.35 mD,so it is classified as tight reservoir.The average gas content of coal rock is 22.53 m^(3)/t,and the average free gas content is 5.65 m^(3)/t,accounting for 25.08%of the total gas content.Fourth,the coal rocks and their different overlying lithologies constitute three reservoir-caprock assemblages,i.e.,coal rock-mudstone,coal rock-limestone and coal rock-sandstone,which control the enrichment and distribution of free gas.On this basis,the coal-rock gas accumulation model of"integrated source and reservoir,continuous hydrocarbon generation,caprock sealing"is put f

关 键 词：鄂尔多斯盆地 石炭系本溪组 二叠系山西组 煤岩气 成藏条件 煤岩气资源量 勘探方向 

分 类 号：TE122[石油与天然气工程—油气勘探]