成岩作用对致密砂岩储层物性的影响——以川中地区上三叠统须四段气藏为例  

INFLUENCE OF DIAGENESIS ON POROPERM CHARACTERISTICS OF TIGHT SAND RESERVOIRS:TAKING THE GAS RESERVOIRS IN THE 4TH MEMBER OF XUJIAHE FORMATION IN THE UPPER TRIASSIC AS EXAMPLES

作　　者：库丽曼[1] 刘树根[1] 朱平[2] 张长俊[2] 雍自权[1] 罗玉宏[3] 龚昌明[3] 

机构地区：[1]"油气藏地质及开发工程"国家重点实验室.成都理工大学 [2]成都理工大学沉积地质研究院 [3]中国石油西南油气田公司川中油气矿研究所

出　　处：《天然气工业》2007年第1期33-36,149-150,共4页Natural Gas Industry

基　　金：新世纪优秀人才支持计划项目(项目编号:NCET-04-0903)

摘　　要：川中地区上三叠统须家河组四段砂岩是四川盆地内的天然气储层之一,该碎屑岩储层具有低孔隙度、低渗透率的特点。在对该区上三叠统须家河组气藏宏观沉积特征研究的基础上,采用岩石薄片、铸体薄片、扫描电镜及X射线衍射等方法,对该气藏储层的成岩作用及其对储集物性的影响进行了探讨,建立了该区致密砂岩成岩作用序列以及孔隙演化模式。研究结论如下:①随压实作用的不断增强,孔隙度呈持续下降的趋势;②成岩作用对致密砂岩储集层的影响具有双重性,压实作用、胶结作用使得砂岩孔隙度降低,而溶蚀作用则增加了孔隙度;③该区的孔隙构成主要是环边绿泥石剩余原生粒间孔以及溶蚀形成的长石、岩屑粒内溶孔,泥质杂基溶蚀粒间孔,伊利石黏土中微孔以及由压实压裂、压实滑动和构造动力所形成的微裂缝孔;④勘探中既要注意机械压实作用、压溶作用对储层的负面影响,同时也要重视成岩早期环边绿泥石胶结物形成、碎屑(主要是长石)及其填隙物溶蚀作用等有利因素。Sandstone in the 4th member of Xujiahe Formation of the Upper Triassic is one of the main gas reservoirs in central Sichuan region and has low permeability and low porosity. Based on the study of macroscopic depositional characteristics of the gas reservoirs in the Upper Triassic Xujiahe Formation in the central Sichuan Basin, various methods, such as core thin section, cast thin section, scanning electron microscope and X ray diffraction, are used to systematically and thoroughly study the diagenesis and its influences on the storage capacity of gas reservoirs, and to build models of diagenesis and porosity evolution of the tight gas sand in the study area. They provide an important basis and information for the study of reservoirs and formation of gas pools. The main types of pores in the study area include remaining original intergranular pore of rim chlorite, dissolved intragranular pore of feldspar and debirs, dissolved intergranular pore of argillaceous matrix, micropore of illite and clay, and micro-fracture resulted from compaction fracturing, compaction slipping and tectonic dynamic force. These types of pores are in good timing with the migration of hydrocarbons, thus consists of the main spaces for accumulation of natural gas. Compaction and cementation are two key factors that resulted in the tight gas sand. The following conclusions are achieved. ①Porosity continuously lowers along with the intensifying of compaction. ②Diagenesis has double-edged influences on tight sand reservoirs, i.e. compaction and cementation lower the porosity of sandstone, while dissolution enhances porosity. ③The pores in the study area are mainly of remaining original intergranular pore of rim chlorite, dissolved intragranular pore of feldspar and debirs, dissolved intergranular pore of argillaceous matrix, micropore of illite and clay, and micro-fracture resulted from compaction fracturing, compaction slipping and tectonic dynamic force. ④Attentions should be paid to both the negative effects of mechanical compactio

关 键 词：四川盆地 中 晚三叠世 致密砂岩 储集层 物性 成岩作用 胶结作用 溶蚀作用 

分 类 号：P618.13[天文地球—矿床学]