乌石凹陷东区流沙港组成岩作用及次生孔隙发育特征

Diagenesis and secondary pore development characteristics of Liushagang formation in the east of Wushi sag

通过岩石薄片、扫描电镜和X射线分析等手段,对乌石凹陷东区流沙港组二段和三段成岩作用及次生孔隙发育特征进行研究。结果表明,乌石凹陷东区流沙港组二段和三段储层处于中成岩阶段A期,纵向上发育4类次生孔隙发育带。Ⅰ类次生孔隙发育带压实作用相对较弱,以原生孔隙为主,次生孔隙起次要作用。Ⅱ、Ⅲ、Ⅳ类次生孔隙发育带随着压实作用的加强,原生孔隙逐渐减少,次生孔隙极大地改善了储层物性。尤其是Ⅱ次类生孔隙带,胶结作用相对较弱,次生孔隙最为发育,且与生油层相邻,是油气勘探开发的有利方向。

Based on microscopic,microscanning and X-ray analysis,the diagenesis and secondary pore development in Liushagang formation in the eastern area of Wushi sag are studied.The results show the reservoirs of the second and third members of the Liushagang formation in the eastern area of the Wushi sag are in the stage A of the middle diagenetic period,and four secondary pore zones are developed longitudinally.The compaction of the 1st secondary pore zone is relatively weak,so the primary pores are the main ones.With the enhancement of compaction in the 2^nd to 4^th secondary pore zones,the primary pores gradually decreased,and the secondary pores greatly improved the reservoir physical properties.Especially in the 2nd secondary pore zone,the secondary pores are most developed because of weak cementation.In addition,the 2^nd secondary pore zone is adjacent to the source rock,which is a favorable direction for oil and gas exploration and development.