顺托果勒柯坪塔格组储层成岩作用与孔隙演化

Diagenesis and Porosity Evolution of Kepingtage Formation in Shuntuoguole Block

针对柯坪塔格组致密砂岩储层成岩作用过程复杂、孔隙演化规律尚待明确等问题,在储层特征研究基础上,系统研究了储层成岩作用类型、成岩阶段划分及成岩序列,恢复其孔隙演化过程。结果表明:顺托果勒区块柯坪塔格组储层以岩屑砂岩、岩屑石英砂岩及长石岩屑砂岩为主,物性较差。储层发育压实作用、胶结作用、溶蚀作用、交代作用、油气充注及构造破裂作用,成岩阶段处于中成岩A期,局部达到中成岩B期。多种成岩作用共同控制着储层的孔隙演化过程,压实作用对孔隙演化的影响最大,平均减孔21.82%;其次为胶结作用,使孔隙度降低约8.18%,其中钙质胶结减孔6.06%,硅质胶结减孔1.80%,黏土矿物胶结影响不明显;沥青充填也导致储层损失了2.53%的孔隙度;溶蚀作用使孔隙度增加了3.91%。

This paper systematically studies the diagenetic types, classification of diagenetic stages and diagenetic sequences, and builds the porosity evolution process. The study shows that the Kepingtage Formation reservoir in Shuntuoguole area, mainly consisting of lithic sandstone, the lithic quartz sandstone and feldspathic litharenite, is poor in physical property. The reservoir, which is predominantly in diagenetic stage A with some parts reaching diagenetic stage B, was mainly controlled by compaction, cementation, erosion, metasomatism, hydrocarbon charging, and tectonic fracturing. Multiple diagenesis fac- tors dominated the reservoir pore evolution： compaction was the most influential with average porosity reduction of 21.82%; cementation was the secondary with porosity reduction of about 8.18% of which calcareous cementation reduced porosity by 6.06%, and silicic cementation reduced porosity by 1.80% while clay cementation gave insignificant influence; bitumen filling led to 2.53% porosity loss; erosion increased porosity by 3.91%.