西湖凹陷斜坡带深层异常高孔隙储层特征及成因  

Characteristics and origin of deep high-porosity zones in slope of Xihu Sag

作　　者：曹茜[1,2] 周文[1,3] 刘岩[1,3] 陈文玲[1,3] 姬安召[4] 吕晶[1,3] 王昱翔[1,3] 

机构地区：[1]成都理工大学油气藏地质及开发工程国家重点实验室,四川成都610059 [2]四川省科源测试中心页岩气评价与开采四川省重点实验室,四川成都610072 [3]成都理工大学能源学院,四川成都610059 [4]陇东学院能源工程学院,甘肃庆阳730070

出　　处：《中南大学学报（自然科学版）》2017年第3期751-760,共10页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(41502135);国家科技重大专项(2011ZX5023-004-009);中国石化股份公司重大勘探先导项目(34000002-12-ZC0613-0015)~~

摘　　要：通过铸体薄片、扫描电镜、黏土矿物X线衍射、压汞和岩心实测孔隙度等资料,研究西湖凹陷斜坡带深层异常高孔隙储层特征及其成因,系统分析异常超压对斜坡带深层异常高孔隙发育带的影响。研究结果表明:西湖凹陷斜坡带深层砂岩储层纵向上3 600~4 300 m及>4 600 m地层异常高孔隙发育,孔隙度最大值为24.9%,对应储集层岩性以长石岩屑砂岩和岩屑长石砂岩为主,砂岩粒度以中—细粒为主,颗粒分选好,颗粒间多为点—线接触,对应孔隙类型包括残余原生粒间孔隙、次生孔隙、铸模孔以及少量裂缝,孔喉组合类型以大孔—粗喉、中孔—中喉型组合为主。研究区异常超压广泛存在,异常超压抑制上覆地层的机械压实作用,保存部分原生孔隙,同时减少了由于胶结作用而损失的孔隙;此外,在一定的封闭系统内异常超压的存在增加了胶结物溶蚀时间和强度,产生大量次生孔隙。The characteristics and origins of deep, high-porosity zones in the slope of Xihu Sag were investigated by thin-section casting, scanning electron microscopy, clay mineral X-ray diffraction, mercury penetration measurement, and core property measurement. The relationship between overpressure and high porosity was studied. The results show that high-porosity zones develop at a depth ranging from 3 600 m to 4 300 m and below 4 600 m, and that the maximum porosity value is 24.9%. The corresponding reservoir rocks are mainly feldspar lithic sandstones and lithic feldspar sandstones with good sorting characteristic and point-to-line contact. The pores include relic primary pores, dissolution pores, mold pores, and a small amount of microfractures. The pore-throat assemblages are mainly moderate pore to moderate throat. Overpressure also extensively occurs in the high-porosity zones in the deep and tight sandstone reservoir. Abnormal pressure slows down the rate of compaction and some intergranular primary pores remain, which decreases porosity caused by cementation. In a closed system, the occurrence of an abnormally high pressure is beneficial for improving the dissolution of cement, which will result in the dissolution of pores, and improve reservoir porosity.

关 键 词：异常高孔隙度 异常超压 储层特征 西湖凹陷 

分 类 号：TE122.2[石油与天然气工程—油气勘探]