Diagenesis and Pore Evolution of Chang 8 Reservoir in Ansai Area
Based on the analysis of reservoir basic characteristics,diagenetic processes,and diagenetic sequences through methods such as thin section identification and scanning electron microscope analysis,the pore evolution of the Chang 8 reservoir in the Ansai area was quantitatively analyzed and a reservoir pore evolution model was established.The research indicates that compaction is the most destructive to the reservoir,being the primary cause of its tightness,reducing porosity by 67.56%.Cementation reduces porosity by 23.65%and is the key factor in achieving tightness during the mid-diagenetic phase A.Dissolution,on the other hand,has a certain ameliorative effect on the reservoir properties,partially slowing down the process of reservoir tightness and increasing porosity by 1.47%.The pore evolution underwent a rapid compaction-early cementation stage during the early diagenetic phase A,followed by a compaction slowing-early dissolution stage in the early diagenetic phase B,and finally an erosion-cementation densification stage during the mid-diagenetic phase A.This study provides a basis for the next step of exploration and development of the Chang 8 reservoir in the Ansai area.
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