川西坳陷中段雷口坡组烃源岩评价及气源分析  

Source Rock and Natural Gas Source of Leikoupo Formation in the Middle Part of West Sichuan Depression

作　　者：王鹏 朱童 徐邱康 陈刚 范厚江 潘树林 Wang Peng;Zhu Tong;Xu Qiukang;Chen Gang;Fan Houjiang;Pan Shulin(College of Resources and Environmental Engineering,Yibin University,Yibin Sichuan 644000,China;Research Institute of Geological Exploration and Development,Chuanqing Drilling Engineering,PetroChina,Chengdu 610051,China)

机构地区：[1]宜宾学院资源与环境工程学院,四川宜宾644000 [2]中国石油集团川庆钻探工程有限公司地质勘探开发研究院,成都610051

出　　处：《地质科技情报》2019年第3期180-187,共8页Geological Science and Technology Information

基　　金：国家自然科学基金项目"川西坳陷上三叠统须家河组储层水岩相互作用机理研究"(41172119);四川省教育厅重点项目"川西坳陷上三叠统须家河组地层水成因研究"(17ZA0454);四川省科技支撑计划项目"川西坳陷东坡沙溪庙组层序地层及其构造控制研究"(2017JY0315)

摘　　要：在对川西坳陷中段雷口坡组烃源岩评价基础上,结合雷口坡组天然气地球化学特征与成藏地质条件分析,探讨了该区不同构造带雷口坡组天然气的气源及差异。烃源岩分析表明:该区雷口坡组烃源岩有机质类型为Ⅱ型,R_o大于2%,但有机质丰度偏低,w(TOC)平均值普遍低于0.3%,普遍未达到有效烃源岩,能为雷口坡组提供的气源非常有限。天然气组分分析显示:新场构造带雷口坡组天然气更富烃类组分,不含或含微量H_2S,而龙门山前构造带雷口坡组天然气更富非烃组分,天然气中H_2S体积分数为3.50%～9.97%,平均值为4.91%,属高含H_2S气藏。受雷口坡组烃源岩生烃有限与雷口坡组多套膏盐层封堵的影响,新场构造带雷口坡组天然气主要来自上覆须家河组烃源岩。龙门山前构造带雷口坡组气藏得益于沟通下伏海相层系的断裂与下伏发育的多套优质烃源岩,下伏海相层系为该区雷口坡组气藏提供了主要的气源。两构造带气源的差异导致了天然气组分特征的显著差异。This paper discusses the source of the natural gas of Leikoupo Formation in the middle part of West Sichuan Depression based on the research of source rocks and geochemical characteristics and accumulation conditions of natural gas. The formation source rock analysis shows that organic type is type II,with Ro value greater than 2%. But the organic abundance is too low, with the TOC value generally less than 0.3%. Accordingly, the source rocks generally are not effective source rocks and cannot provide enough gas for Leikoupu Formation reservoir. The research of component of Leikoupo Formation natural gas shows that the gas in the Xinchang tectonic belt is more enriched in hydrocarbon and contains no or trace of H2S. But in the Longmenshan piedmont tectonic belt, the natural gas is more enriched in nonhydrocarbon, with H2S content ranging from 3.50% to 9.97% and averaged at 4.91%, thus illustrating that the gas reservoir is a high H2S gas reservoir. Influenced by the limited hydrocarbon generation of the source rocks of the Leikoupo Formation and the blocking of multiple layers of the gypsum salt in the Leikoupo Formation, the natural gas of the Leikoupo Formation in the Xinchang tectonic belt is mainly from the source rocks of the uplap Xujiahe Formation. Because there are many faults connecting the underlying marine strata and sets of high quality source rocks, the underlying marine source rocks provide the main gas for the Leikoupo Formation gas reservoir in the Longmenshan piedmont tectonic belt. The dfferent gas sources are the main reason for the difference of natural gas components.

关 键 词：川西坳陷 雷口坡组烃源岩 雷四段气藏 龙门山前构造带 气源 

分 类 号：P618.13[天文地球—矿床学] TE122[天文地球—地质学]