川东侏罗系凉高山组页岩沉积环境特征及有机质富集机理  

Characteristics of the shale sedimentary environment and organic matter enrichment mechanism in the Jurassic Lianggaoshan Formation in the East Sichuan Basin

作　　者：郭战峰[1] 舒逸 陈绵琨[2] 刘皓天[2] 彭伟[2] 肖雄[2] GUO Zhanfeng;SHU Yi;CHEN Miankun;LIU Haotian;PENG Wei;XIAO Xiong(Jianghan Oilfield Branch Company,SINOPEC,Qianjiang Hubei 433124,China;Research Institute of Exploration and Development,Jianghan Oilfield Branch Company,SINOPEC,Wuhan 430223,China)

机构地区：[1]中国石油化工股份有限公司江汉油田分公司,湖北潜江433124 [2]中国石油化工股份有限公司江汉油田分公司勘探开发研究院,武汉430223

出　　处：《地质科技通报》2024年第4期62-74,共13页Bulletin of Geological Science and Technology

基　　金：中国石油化工股份有限公司“十条龙”科研项目“复兴侏罗系陆相页岩油气藏地质评价技术”(P21078-2);中国石油化工股份有限公司科研项目“川东地区重点层系页岩气成藏条件与评价技术研究”(P23077)。

摘　　要：四川盆地东部复兴地区泰页1井和兴页L1井均在侏罗系凉高山组页岩段测试获得高产油气流,试采效果好,实现了川东侏罗系陆相页岩油气勘探重大突破。为进一步明确川东侏罗系凉高山组页岩油气勘探潜力及有机质富集机理,选取复兴地区兴页X井、兴页Y井作为典型代表,综合测录井、岩心资料和全岩X衍射、有机碳、主微量元素等分析测试方法研究表明:凉二下亚段页岩沉积古气候处于暖湿型环境(中等风化条件),不同单元地层沉积的古气候之间无明显差异,处于淡水-微咸水沉积环境。通过镧-钴法计算古水深整体介于10.9~56.1 m之间,属于半深湖-深湖沉积环境,自下而上沉积水体深浅交替,整体古生产力呈现增大的趋势,页岩段总体上处于缺氧还原环境,发育砂质纹层,沉积速率相对砂岩段较小。通过不同沉积环境参数与w(TOC)相关性分析,凉二下亚段页岩有机质富集主要受古水深、古氧化还原环境、沉积速率和古生产力等多因素耦合控制作用,古盐度和古气候条件影响相对较小。沉积环境的差异控制了页岩纵向上非均质性特征,其中⑥号单元页岩相形成于深水缺氧沉积环境,具有低沉积速率、高古生产力及受陆源影响较小的特点,为有机质的富集提供了有力条件,为有利勘探目的层。[Objective]The good oil test results of Taiye 1 and Xingye L1 wells in the Jurassic Lianggaoshan Formation shale indicate the breakthrough of shale oil/gas exploration in the Jurassic continental shale in the Fuxing area of the eastern Sichuan Basin.To further clarify the oil/gas exploration potential and the organic matter enrichment mechanism of the Jurassic Lianggaoshan Formation shale,utilizing logging and core data of two typical wells Xingye X and Xingye Y,the whole-rock X-ray diffraction,organic carbon,major and trace elements were analyzed.[Methods]The Liang-2 lower submember was deposited in the environment of warm-wet(moderate weathering conditions)and freshwater,and there was no obvious difference in palaeoclimates of different unit formations.The La-Co data suggests a semi-deep to deep lake environment with a palaeowater depth ranging from 10.9 to 56.1 m;the anoxic reducing environment persisted on the lake floor despite the lake level fluctuation,but the palaeoproductivity was vertically increased.The shale interval is rich in sandy laminae,but the deposition rate of the shale layer is lower than that of the sandstone layer.[Results]According to the correlation analysis between sedimentary environment parameters and organic carbon content(TOC),the organic matter enrichment in the Liang-2 lower submember shale was mainly controlled by factors of palaeowater depth,palaeoredox environment,deposition rate,and palaeoproductivity,and slightly affected by the palaeosalinity and palaeoclimate conditions.The variation in the deposition environment resulted in the vertical heterogeneity of shale.[Conclusion]The shale facies of Unit 6,formed in the good conditions for the organic matter enrichment referring to an anoxic environment in deep water,with a low deposition rate,a high palaeoproductivity,and the slight influence of terrigenous sources,was a favorable target layer for exploration.

关 键 词：侏罗系 凉高山组 页岩 沉积环境 有机质富集机理 

分 类 号：P618.13[天文地球—矿床学]