Combining small well spacing with polymer flooding to improve oil recovery of marginal reservoirs

Abstract

The recovery factor of water flooding is very low in some continental and heterogeneous sandstone oil fields,especially when the reservoir continuity is poor,permeability low and high permeability variation between different zones.Because the amount of incremental producible oil is not large enough to further drill infill wells economically,drilling infill wells and performing polymer flooding simultaneously was proposed and a pilot test has been conducted.This paper introduces the laboratory studies on selection of polymer injection parameters and project design optimization.Under well spacing of 100 m,the zones with a thickness of less than 1m and with a permeability range of 5 to 100 md were combined together and put on development.Both lab studies and pilot results show that the recovery factor has over 10% increase,especially after applying separate zone injection measures in polymer injectors.The pilot test indicates that the technique of combining infill wells with polymer flooding is economically feasible.