绿泥石环边胶结物对致密砂岩孔隙的保存机制—以川中-川南过渡带包界地区须家河组储层为例

Pore-preserving mechanism of chlorite rims in tight sandstone—an example from the Tx Formation of Baojie area in the transitional zone from the central to southern Sichuan Basin

刘金库 彭军 刘建军 汪彦 刘建锋

Liu Jinku Peng Jun Liu Jianjun Wang Yan Liu Jianfeng

用薄片鉴定、扫描电镜等分析手段,对川中-川南过渡带荷包场、界市场地区(简称包界地区)上三叠统须家河组砂岩储层中绿泥石环边胶结物的产状、形成条件及其对储层孔隙的保存机制进行了研究。结果表明,绿泥石环边胶结物以等厚环边方式垂直颗粒表面生长,此类胶结物形成于早成岩阶段,其形成过程主要受沉积环境和物源条件控制;绿泥石环边胶结物的存在提高了岩石的抗压实能力,抑制了石英次生加大,促进了溶蚀作用,形成了有利的孔隙结构。因此,绿泥石环边胶结物对该区致密砂岩储层残余原生孔隙的保存起到了至关重要的作用。

The occurrence,forming conditions,and pore-preserving mechanism of chlorite rims in the Upper Triassic Xuejiahe Formation of Baojie area from central to southern Sichuan basin were studied in detail by means of thin section analysis and SEM analysis.The result shows that chlorite rims grew vertically on the grain surface and took the shape of isopachous grain-coating.This kind of cement was formed during the early diagenetic stage and was controlled mainly by depositional environment and provenance conditions.The presence of chlorite rims enhanced the compaction resistance of rock,inhibited quartz overgrowth on detrital-quartz grains,accelerated dissolution and formed excellent pore-throat configuration.Therefore,the chlorite rims played an important role in the preservation of residual primary pores in the tight sandstone reservoirs in the study area.

10.11743/ogg20090108