Abstract:

In order to find out distribution zones of high-quality reservoirs in Penglai area, based normal thin sections, casting thin sections, scanning electron microscope analysis data and core data, the reservoirs have been worked on lithological characteristics, reservoir property and pore structure, diagenesis, diagenetic minerals, diagenetic environment, diagenetic stage and diagenetic evolution sequence in Member 2 of Xujiahe Formation. The results show that the reservoirs have experienced diagenesis such as compaction, cementation, corrosion, and fracture, it is now in the stage A of middle diagenetic stage. Three types of diagenetic facies are divided based on diagenesis, diagenetic minerals and their effect on the reservoir quality, these facies include high compactionauthentic minerals cementation facies, high compactioncorrosion of unstable components facies, and tectonic fracture facies. According to various well logging response characteristics, five normal logging curves and imaging logging data which are sensitive to the diagenetic facies are chosen to characterize diagenetic facies, which include compensated neutron logging(CNL), density logging(DEN), acoustic slowness(AC), natural gamma ray(GR), resistivity log(R_t) and EMI, different types of diagenetic facies has various response characteristics on various logging curve and their combination, and the vertical and plane distribution of diagenetic facies can be figured out with well logging data. The favorable diagenetic facies are used to optimize favorable regions of oil and gas bearing zones. The high quality reservoir distributed in the middle part of the slope on the plane surface.

Key words: diagenetic facies, Penglai area in central Sichuan basin, Member 2 of Upper Triassic Xujiahe Formation, logging recognition methods, high quality reservoirs