四川盆地上奥陶统五峰组—下志留统龙马溪组页岩气藏超压成因及演化规律  

Origin and evolution of overpressure in shale gas reservoirs of the Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation in the Sichuan Basin

作　　者：唐令 宋岩[2] 赵志刚[1] 姜振学 蒋恕[3] 陈晓智[1] 李卓 李倩文[4] TANG Ling;SONG Yan;ZHAO Zhigang;JIANG Zhenxue;JIANG Shu;CHEN Xiaozhi;LI Zhuo;LI Qianwen(Research Institute Co.,Ltd.of CNOOC,Beijing 100028,China;Unconventional Oil&Gas Science and Technology Research Institute,China University of Petroleum-Beijing,Beijing 102249,China;Faculty of Earth Resources,China University of Geosciences-Wuhan,Wuhan,Hubei 430074,China;Sinopec Petroleum Exploration&Production Research Institute,Beijing 102206,China)

机构地区：[1]中海油研究总院有限责任公司 [2]中国石油大学(北京)非常规油气科学技术研究院 [3]中国地质大学(武汉)资源学院 [4]中国石化石油勘探开发研究院

出　　处：《天然气工业》2022年第10期37-53,共17页Natural Gas Industry

基　　金：国家科技重大专项“五峰—龙马溪组富有机质页岩储层精细描述与页岩气成藏机理”(编号:2017ZX05035002)、中海石油(中国)有限公司北京研究中心科研项目“中海油油气勘探战略选区研究”(编号:20210T-XNY01)。

摘　　要：四川盆地上奥陶统五峰组—下志留统龙马溪组页岩气藏普遍存在超压现象,但目前对于页岩气藏超压形成的原因及演化过程尚不清楚。为了揭示五峰组—龙马溪组页岩气藏超压的形成机制与演化规律,利用测井、数值模拟和激光拉曼实验等方法,综合判识了五峰组—龙马溪组页岩超压成因机理,并基于正演模拟联合反演方法验证了埋藏—抬升全过程的压力动态演化,进而建立了盆内、盆缘和盆外的超压发育模型。研究结果表明:①采用测井组合法、鲍尔斯法、声波速度—岩石密度交汇图版法综合判识出五峰组—龙马溪组页岩的超压成因属于生烃膨胀增压机制;②生烃增压与有机质丰度及类型、原始氢指数、干酪根质量分数及转化率、原油裂解率和滞烃系数等因素密切相关;③焦石坝地区五峰组—龙马溪组页岩干酪根生油可致储层地层压力系数增至1.73,理论计算原油裂解生气可致储层地层压力系数增至2.78,原油裂解生气增压贡献率远大于生油增压;④川南地区五峰组—龙马溪组页岩中流体包裹体的平均捕获压力为163.20 MPa,平均地层压力系数为2.51;⑤焦石坝地区构造抬升过程中因温度下降、孔隙回弹和页岩气散失分别引起地层压力下降44.16 MPa、40.28 MPa和36.50 MPa。结论认为,超压成因和演化的系统研究有助于页岩气差异富集成藏理论的认识,对指导四川盆地及其周缘地区复杂构造背景下海相页岩气选区评价具有重要意义。Overpressure is common in the shale gas reservoirs of the Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation in the Sichuan Basin.However,the origin and evolution process of overpressure in shale gas reservoirs has not been understood clearly.In order to reveal the formation mechanism and evolution law of overpressure in the Wufeng Formation–Longmaxi Formation shale gas reservoirs,based on well logging,numerical simulation and Laser Raman experiments,the formation mechanism of overpressure in the Wufeng Formation–Longmaxi Formation was comprehensively identified,the dynamic evolution of overpressure during burial and uplift was verified by forward and inversion simulation,and the overpressure development model of the Wufeng Formation–Longmaxi Formation inside,margin and outside of basin were established.The following results were achieved.(1)Hydrocarbon generation pressurization is the formation mechanism of overpressure in the Wufeng Formation–Longmaxi Formation by well logging combination methods,Bowers method and acoustic velocity–rock density cross plot.(2)Hydrocarbon generation pressurization is closely related to the abundance and type of organic matter,original hydrogen index,kerogen mass fraction and conversion rate,oil cracking rate and residual hydrocarbon coefficient.(3)The formation pressure coefficient of the reservoir during kerogen oil-generating can reach 1.73 in the Wufeng Formation–Longmaxi Formation of the Jiaoshiba area,while it can reach 2.78 during oil gas-cracking by theoretical calculation.The pressurization contribution of oil gas-cracking is much greater than that of kerogen oilgenerating.(4)The average capture pressure in the Wufeng Formation–Longmaxi Formation shale in the southern Sichuan Basin is 163.20 MPa and the average formation pressure coefficient is 2.51.(5)During the tectonic uplift in the Jiaoshiba area,the formation pressure decreased by 44.16 MPa,40.28 MPa and 36.50 MPa respectively due to temperature drop,pore rebound and shale gas loss.It

关 键 词：四川盆地 上奥陶统五峰组—下志留统龙马溪组 超压成因 生烃膨胀 增压模式 超压演化 埋藏—抬升 

分 类 号：P618.13[天文地球—矿床学]