苏里格气田苏6区块盒8段致密砂岩储层次生孔隙成因探讨  

Genesis of secondary pores of tight sandstone reservoir in He 8th Member in Su 6 area of Sulige gas field

作　　者：毕明威 陈世悦 周兆华[2] 刘金 郑国强[2] 张满郎[2] 

机构地区：[1]中国石油大学地球科学与技术学院,山东青岛266580 [2]中国石油勘探开发研究院廊坊分院,河北廊坊065007

出　　处：《中国石油大学学报（自然科学版）》2015年第1期8-16,共9页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家科技重大专项(2011ZX05013-002)

摘　　要：利用岩石薄片、扫描电镜、电子探针、能谱分析、包裹体测温及拉曼光谱分析等方法,对苏里格气田苏6区块下石盒子组8段储层的孔隙发育特征进行研究。结果表明:储层残余原生粒间孔占现今孔隙的3.0%,次生孔隙中溶蚀孔隙占67.5%,黏土矿物晶间孔占29.5%;储层次生孔隙的形成主要经历两期溶蚀作用,Ⅰ期溶蚀为酸性环境下长石、岩屑等的溶蚀,形成的次生孔隙多在后期成岩过程中损失,Ⅱ期溶蚀为偏碱性环境长石、高岭石等的溶蚀,形成的次生孔隙对现今储层起到主要的贡献;偏碱性环境下钾长石的溶解为高岭石的伊利石化反应提供K+,促进了高岭石的转化,而高岭石的伊利石化使得孔隙流体中K+的浓度降低,促进了长石的溶解,两者的协同反应是次生孔隙形成的主要原因;Ⅰ期溶蚀作用的强弱直接关系到Ⅱ期溶蚀反应的程度,Ⅰ期溶蚀反应强烈,能够保证Ⅱ期溶蚀协同反应的充分进行。Pore characteristics of the tight sandstone reservoir of the 8th Member of the Lower Shihezi Formation in Su 6 area of Sulige gas field were analyzed using a series of techniques,including thin section identification,scan electron microscope,electron probe micro-analysis and energy spectrum,homogenization temperatures and Raman microprobe method of fluid inclusions. The results show that primary remained intergranular pores account for 3. 0% of total pores,and the secondary pores which contain dissolved pores and intercrystalline pores in clay minerals,account for 67. 5% and 29. 5% respectively.There are two stages of dissolution to form the secondary pores. The first dissolution is the dissolution of feldspar and debris dissolution under acid condition,and the early dissolution pores are usually damaged and disappeared after the later compaction and cementation. The second dissolution under mild alkaline condition dissolves feldspar and kaolinite to form secondary pores and illite,which has a main contribution to reservoir. Dissolution of potassium feldspar provides K＋to the transformation of kaolinite to illite to promote the transformation of kaolinite,and the transformation of kaolinite results in reducing K＋concentration to promote the dissolution of potassium feldspar. The two processes（ cooperative reaction） cooperating with each other are the dominant reasons of generation of secondary pores. The extent of first dissolution directly affects the second dissolution,and the strong dissolution reaction of first dissolution should be helpful in finishing the cooperative reaction of second dissolution.

关 键 词：致密砂岩储层 次生孔隙 偏碱性环境 苏里格气田 

分 类 号：TE122.2[石油与天然气工程—油气勘探]