四川盆地五峰组—龙马溪组深水陆棚相页岩生储机理探讨  

Hydrocarbon generation and storage mechanisms of deep-water shelf shales of Ordovician Wufeng Formation–Silurian Longmaxi Formation in Sichuan Basin, China

作　　者：郭旭升[1] 李宇平[1] 腾格尔[2] 王强[1] 袁桃 申宝剑[2] 马中良[2] 魏富彬 HONG Difeng;TANG Xueping;GAO Wenkai;MAO Weimin;WANG Peng;LIU Ke(CNPC Engineering Technology R&D Company Limited,Beijing 102206,China)

机构地区：[1]中国石化勘探分公司 [2]中国石化石油勘探开发研究院无锡石油地质研究所

出　　处：《石油勘探与开发》2020年第1期193-201,共9页Petroleum Exploration and Development

基　　金：国家科技重大专项“页岩气区带目标评价与勘探技术”（2017ZX05036）;“重点地区页岩气富集规律与勘探评价方法”（2017ZX05036001）

摘　　要：针对上奥陶统五峰组—下志留统龙马溪组优质页岩生储机理不清的问题,以四川盆地五峰组—龙马溪组深水陆棚相优质页岩为研究对象,结合页岩气形成地质条件和实验分析模拟,从岩石学、矿物学、地球化学等多方面对页岩成烃、成储机制及内在耦合关系等进行分析。结果表明,四川盆地五峰组—龙马溪组优质页岩热演化程度高、生烃强度大、物质基础好,具有良好的顶底板条件;深水陆棚相优质页岩不仅具有高生物成因硅、高有机碳含量,而且具有相对高孔隙度耦合特征。研究认为:①四川盆地五峰组—龙马溪组高演化深水陆棚相优质页岩保存条件好,早期原油滞留效率高,其气源主要来自原油滞留裂解气。②深水陆棚相生物成因的硅质(蛋白石A),在埋藏成岩早期转化成高硬度晶态石英,伴生形成大量微米级粒间孔,而生物成因的硅质格架抗压性强,为优质页岩储集层早期原油充注及纳米级蜂窝状有机孔的发育和保持提供了空间和保护,是有机孔得以保存的关键因素。③五峰组—龙马溪组优质页岩脆性好,均质性强,微米级硅质粒间孔与纳米级有机孔共生,是压裂形成复杂缝网、硅质粒间纳米级有机孔实现高效连通的关键,有利于页岩气高产、稳产。As the hydrocarbon generation and storage mechanisms of high quality shales of Upper Ordovician Wufeng Formation– Lower Silurian Longmaxi Formation remain unclear, based on geological conditions and experimental modelling of shale gas formation, the shale gas generation and accumulation mechanisms as well as their coupling relationships of deep water shelf shales in Wufeng-Longmaxi Formation of Sichuan Basin were analyzed from petrology, mineralogy, and geochemistry. The high quality shales of Wufeng-Longmaxi Formation in Sichuan Basin are characterized by high thermal evolution, high hydrocarbon generation intensity, good material base, and good roof and floor conditions;the high quality deep-water shelf shale not only has high biogenic silicon content and organic carbon content, but also high porosity coupling. It is concluded through the study that:(1) The shales had good preservation conditions and high retainment of crude oil in the early times, and the shale gas was mainly from cracking of crude oil.(2) The biogenic silicon(opal A) turned into crystal quartz in early times of burial diagenesis, lots of micro-size intergranular pores were produced in the same time;moreover, the biogenic silicon frame had high resistance to compaction, thus it provided the conditions not only for oil charge in the early stage, but also for formation and preservation of nanometer cellular-like pores, and was the key factor enabling the preservation of organic pores.(3) The Wufeng-Longmaxi Formation high quality shale had high brittleness, strong homogeneity, siliceous intergranular micro-pores and nanometer organic pores, which were conducive to the formation of complicated fissure network connecting the siliceous intergranular nano-pores, and thus high and stable production of shale gas.

关 键 词：生储机理 上奥陶统五峰组 下志留统龙马溪组 深水陆棚 硅质页岩 四川盆地 孔隙保存 

分 类 号：TE122[石油与天然气工程—油气勘探]