伊川盆地上三叠统储层成岩作用与孔隙演化

Diagenesis and porosity evolution of the reservoirs from the upper Triassic in the Yichuan basin

伊川盆地上三叠统砂岩致密,非均质性强,对成岩作用及其孔隙演化的认识不清,在一定程度上制约了油气勘探的部署。通过薄片、扫描电镜和X射线等分析结果的研究,结合埋藏史、热史等资料,认为伊川盆地上三叠统储层以岩屑细砂岩、长石细砂岩为主,物性总体较差,属于低孔、低渗砂岩储层。上三叠统成岩作用主要为中成岩A期,早成岩期的压实作用和胶结作用是孔隙度降低的主要原因,长石溶蚀作用形成的次生孔隙对砂岩的储集性能具有明显的改善作用;油气充注之前的早成岩期储层已经致密化。

The formation of the upper Triassic sandstone in the Yichuan basin is dense and the heterogeneity is strong.Due to unclear understanding of diagenesis and its pore evolution,the hydrocarbon deployment was restricted to some extent.Through thin section,scanning electron microscopy(SEM) and X-ray analysis of the results of research,combined with the burial history,thermal history and other information,the Triassic reservoirs of Yichuan basin are mainly of fine sandstone and feldspar lithic sandstone,with poor physical properties in general,which belongs to low porosity and low permeability sandstone reservoir.Diagenesis of upper Triassic belongs to stage A of middle diagenesis phase.The early diagenetic compaction and cementation are main factors to decreasing porosity of reservoir.The formation of secondary porosity in feldspar corrosion has obvious effect on sandstone reservoir performance.The early diagenesis reservoir has been densified before oil and gas filling.