鄂尔多斯盆地华池长8储层成岩相与孔隙度演化

Reservoir Diagenetic Facies and Porosity Evolution Pathways of Chang 8 Formation in Huachi,Ordos Basin

为探讨成岩作用与储层物性演化特征之间的成因联系,查明不同成岩相物性差异的成因及其形成过程,对华池地区长8储层各成岩相的孔隙度演化进行了定量模拟,分析了其孔隙度演化路径的差异.本区绿泥石膜胶结成岩相、不稳定组分溶蚀成岩相、压实充填成岩相与碳酸盐致密胶结成岩相压实损失孔隙度分别为17.6%、20.5%、25.8%和11.4%,早期胶结损失孔隙度为4.5%、4.9%、5.6%和24.9%,溶蚀增加孔隙度为1.4%、2.3%、0.2%和0,晚期胶结损失孔隙度为7.8%、9.7%、3.2%和0.沉积物初始组构差异造成的各成岩相初始孔隙度差别是微小的,但其在很大程度上控制了成岩作用的类型和强度,从而造成了不同成岩相经历了不同的成岩变化过程和孔隙度演化路径,形成了现今组构面貌和孔隙度的差异.

In order to analyze the genetic relationship between diagenesis and reservoir porosity evolution process and the forma tion process of physical property difference in different diagenetic facies, diagenesis types and facies of Chang 8 formation are studied in Huachi, Ordos basin. Furthermore, porosity evolutions of different diagenesis facies are simulated quantitatively, and their pathways are analyzed. According to the diagenesis characteristics, the reservoirs can be divided into four diagenesis facies, namely, grain-coating chlorite cementation, corrosion of unstable components, intense compaction with packing and dense carbonate cementation. COPL （compactional porosity loss） of them are 17.6%, 20.5%, 25.8% and 11.4% respectively CEPL （cementational porosity loss） by early quartz overgrowth, grain-coating chlorite, and carbonate are 4.5%, 4.9%, 5.6% and 24.9% respectively; CRPI （corrosional porosity increase） are 1.4%, 2.3%, 0.2% and 0 respectively; CEPL by late pore filling chlorite, kaolinite, illite, ferrocalcite and ferrodolomite are 7.80/oo, 9.7%, 3.2% and 0 respectively. The porosity evolu tion pathways of different diagenesis facies show that the differences of OP （original porosity） caused by the sediment components and structures are tiny, but the diagenesis types and grades are controlled by sedimentary processes to a great extent. It is concluded that the reservoirs with diagenesis facies have different diagenetic changes and porosity evolution pathways, which results in differences of components, structures and physical properties.