西湖凹陷斜坡带深层异常高孔隙储层特征及成因

来源期刊:中南大学学报(自然科学版)2017年第3期

论文作者:周文 曹茜 刘岩 陈文玲 姬安召 吕晶 王昱翔

文章页码:751 - 761

关键词:异常高孔隙度;异常超压;储层特征;西湖凹陷

Key words:high-porosity zones; abnormal overpressure; reservoir characteristics; Xihu Sag

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。

Abstract: 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.

有色金属在线官网  |   会议  |   在线投稿  |   购买纸书  |   科技图书馆

中南大学出版社 主办 版权声明   电话:0731-88830515 88830516   传真:0731-88710482   Email:administrator@cnnmol.com

互联网出版许可证:(署)网出证(湘)字第028号   湘ICP备09001153号