摘要:
成岩相作为油气勘探过程中的热门方法,其定义的不同造成研究成果的差异。前期通过对苏里格气田东二区盒8段储层岩石学和成岩作用的详细研究,按照邹才能等(2008)提出的成岩相分类和命名原则,将研究区盒8段储层划分为五种成岩相。此次研究结合流体包裹体的分析测试结果,对研究区盒8段储层的成岩环境进行了分析,并利用成岩环境对其成岩相进行了再研究,在原研究程度的基础上完善了成岩相的形成过程和形成阶段。研究区盒8段储层在成岩过程中经历了淡水-弱酸性的大气成岩环境、弱酸性-酸性的埋藏成岩环境和弱碱性的埋藏成岩环境。受成岩环境的影响,形成了不同的成岩相:同生成岩-早成岩A早期受大气淡水、弱酸性埋藏成岩环境的影响,主要发生压实、弱酸性溶蚀作用形成弱溶蚀-压实相;早成岩A晚期-早成岩B期受弱酸性埋藏成岩环境的影响,压实作用与酸性溶蚀作用持续增强,形成溶蚀-压实相;中成岩A期-中成岩B早期为酸性埋藏成岩环境,广泛产生胶结作用与酸性溶蚀作用,形成溶蚀-胶结相;中成岩B晚期表现为碱性埋藏成岩环境,主要发生碱性交代作用,形成交代相。根据储层成岩相的影响因素:岩性、成岩环境、成岩作用类型和孔隙结构特征,按照"成岩相是成岩环境的物质表现"的定义,提出采用"岩性+成岩环境+(孔渗级别)+主要成岩作用"的命名方法,将苏里格气田东二区盒8段储层成岩相划分为五种类型:中细粒(杂)砂岩大气环境致密压实相;净砂岩大气、酸性埋藏环境特低孔渗溶蚀-压实相;净砂岩酸性埋藏环境低孔渗溶蚀相;净砂岩酸性埋藏环境特低孔渗溶蚀-胶结相以及净砂岩碱性埋藏环境致密交代相。
Abstract:
Diagenetic facies is a popular method in the exploration of oil and gas, however, there were different research achievements because of the different definition. Based on the detailed research of petrology and diagenesis of reservoir in He8 section of Shihezi Formation, EastⅡpart of Sulige Gas Field, there were five kinds of diagenetic facies in He8 section of the study area, according to Zou(2008)'s classification and nomenclature of diagenetic facies. Combining with fluid inclusions analysis results, the diagenetic environments in He8 section of East Ⅱ part of Sulige Gas Field were analyzed, and restudied the diagenetic facies according to the diagenetic environments, which improved the forming process and stages of diagenetic facies. The reservoirs in He8 section were undergone three kinds of diagenetic environments:neutral to weak acid atmospheric diagenetic environment, weak acid to acid burial diagenetic environment and weak alkaline burial diagenetic environment, different diagenetic facies were produced in different diagenetic environments. Weak dissolution-compaction facies was formed due to the compaction and weak acid dissolution in the Syndiagenetic-Period A of Early diagenetic stage, with atmosphere and acidic burial environment. There was weak acidic buried environment of Period A-Period B of Early diagenetic stage, due to the enhancing compaction and dissolution, dissolution-compaction facies was formed. Cementation and acid dissolution were the main diagenesis of the Period A-early Period B of Middle diagenetic stage, so dissolution-cementation facies was formed in the stage. And metasomatic facies was dominated by the alkaline metasomatism and cementation in late Period B of Middle diagenetic-Epigenetic stage, so the metasomatic facies was mainly formed in the alkaline burial environment when the diagenetic evolution had been up to the Period B of Middle diagenetic stage. According to the definition that diagenetic facies is the material performance of diagenetic environment, "lithology+diagenetic environment+(physical characteristics)+main diagenesis" is as the basis to divide diagenetic facies. Following the classification scheme, five types of diagenetic facies are divided for the reservoirs in He8 section:Dense compaction facies of greywacke in atmosphere environment, Dissolution-compaction facies of arenite with extra low porosity and permeability in atmosphere and acidic burial environment, Dissolution-cementation facies of arenite with extra low porosity and permeability in acidic burial environment, Dissolution facies of arenite with low porosity and permeability in acidic burial environment, and last, Dense metasomatic facies of arenite in alkaline burial environment.
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