塔河地区西南缘东河砂岩的成岩作用与孔隙演化

Diagenesis and porosity evolution of Donghe sandstone in southwest of Tahe area

分布于塔河地区西南缘东河砂岩的储层物性明显比塔里木盆地其他地区的东河砂岩的储层物性差。通过对岩心、岩石薄片的观察，结合电镜扫描、阴极发光等分析方法，对研究区东河砂岩储层的成岩变化作用及其对孔隙形成与演化的关系进行研究。研究结果表明：对孔隙形成与演化起主要控制作用的成岩作用是埋藏压实、石英的次生加大、碳酸盐的胶结及溶蚀溶解；埋藏压实使原始孔隙减少10％～15％，石英的次生加大则可使孔隙减少2％～5％，多期次的大量碳酸盐胶结物也使储层的物性变差及非均质性变强；溶蚀溶解作用可使储层孔隙增加5％～8％；导致区内东河砂岩储集物性较差的主要因素除了受沉积环境的影响之外，还受邻近碳酸盐岩剥蚀区大量的碳酸盐物质的注入和胶结的影响。

The reservoir physical property of Donghe sandstone in southwest of Tahe areas is inferior to other area in Tarim. Donghe sandstone diagenesis as well as its effects on porosity formation and evolution were studied through core and rock slice observation and data analysis of scanning electron microscope and cathodoluminescence in the studied area. Main effects of diagenesis on porosity formation and evolution are compaction during burying, quartz secondary enlargement, carbonate cementation and dissolution. The compaction makes primal porosity 10%-15% less, the quartz secondary enlargement reduces it by 2%-5%. Several periods of carbonate cementation leads to reservoir physical property inferior and heterogeneity stronger. Dissolution increases reservoir porosity by 5%-8%. The main factors, which lead to the poor reservoir physical property of Donghe sandstone are the entering of considerable amount of carbonate from nearby erosion area and the carbonate cementing in addition to sedimentary environment.