CARBONIFEROUS RESERVOIR CHARACTERISTICS AND ITS DISTRIBUTION IN EASTERN CHONGQING

The reservoirs in eastern Chongqing are deeply studied based on lithologic characteristics, reservoir property, micropore structure and main control factors. According to logging -reservoir processing and seismic -reservoir prediction, the reservoir distribution has been studied. It is considered that the Carboniferous reservoir characteristics in eastern Chongqing are similar to those in East Sichuan. Reservoir properties with low porosity and low permeability in the 2nd Member of Huanglong Formation are best. Reservoir rocks include grain limestone, crystal limestone and breccia limestone. Reservoir spaces are pores, fractures and caves. Main pore types are classified into intragranular solution pore and intragranular solution pore. Fractures are very developed in reservoir rocks. The reservoir type is fractured-porous type, with type II and III as the soul. Simultaneously reservoirs are affected and controlled by sedimentary microfacies, diagensis and epigenetic tectonism. Vertically, reservoirs are distributed in the 2nd Member of Huanglong Formation. The reservoir thickness varies from 0 m to 30 m , generally thicker in the west and thinner in the east. With NE-SW-ward favorable reservoirs mainly distribute at Chi 34-Zhaigou 4 and Yunan 3 wellblocks .