Micro-pore Structure and Percolation Characteristics of Upper Neogene Lacustrine Carbonate Reservoir in Nanyishan

The reservoir lithology of Youshashan Formation of oil-bearing series in Nanyishan Oilfield was lake-facies carbonate-rock. The rock types was composed of grain limestone, grain dolomite, algal limestone, micritic limestone, micritic limestone and a part of fine grained detrital rock, of which grain carbonate was main reservoir lithology. Due to the weak lake water energy, the size of deposited grain carbonate and pore throat of reservoir were fine, fissures were not well-developed and storage-permeation performance of reservoir was poor in this area. Oil well productivity and oil recovery rate were low, water well injection was difficult and development efficiency was poor. Thus, the key of raising reservoir development and ultimate recovery percent is to intensify microscopic study on reservoir pore structure and percolation characteristics.