STUDY ON THE SEQUENCE DIVISION AND RESERVOIR OF MIDDLE PERMIAN IN CENTRAL SICHUAN BASIN, CHINA

摘要

Carbonate reservoirs are developed in Qixia and Maokou Formations of Middle Permian in central Sichuan. In this paper, the sequence of the study area is divided according to the core and logging data, and the reservoir characteristics are also studied. The results show that (i) Qixia Formation can be divided into one third order sequence and Maokou Formation can be divided into two third-order sequences. Each third order sequence can be subdivided into two system tracts, transgression system tract (TST) and highstand system tract (HST); (ii) Reservoirs in the study area mainly include dolomite, bioclastic limestone and fine crystalline limestone. Reservoir space types can be divided into pores, caves and fractures. The study area develops low porosity and low permeability reservoir; (iii)The porosity of Qixia Formation reservoir is mainly between 2% and 4%, the permeability is mainly between 0.1mD and 1 mD, the porosity of Maokou Formation reservoir is mainly between 0 and 2%, and the permeability is mainly between 0.1 and 1 mD.