Practice and Recognition of Polymer-Surfactant Combination Flooding in Thick Sandstone Reservoir

In China, the practice of conducting chemical flooding in thick sandstone reservoirs has always faced numerous challenges, and there has been no successful precedent up to now. In 2015, Liaohe Oilfield selected 5 well groups in the third layer system of Block J16 to conduct field test on polymer-surfactant combination flooding in thick sandstone reservoirs. Through in-depth analysis of the effects of the field test over nearly a decade, the development laws and displacement effects of chemical flooding in thick reservoirs have been more deeply understood. At the same time, relevant research on the reasonable injection mode of chemical flooding in thick layers has been carried out to verify the feasibility of chemical flooding in thick sandstone reservoirs. Finally, by means of optimizing the injection-production layers and parameters, the chemical flooding effect has been improved, and the central well group is expected to increase the recovery rate by more than 15%. This field test shows that the effects of chemical flooding will be greatly affected by the lack of development of inter-layer, low physical property section and external water intrusion. The key to improving the utilization of top remaining oil is to narrow the well section, strengthen top injection and production, increase viscosity, and expand sweep. The test results can provide an important basis for the large-scale promotion of chemical flooding in this type of reservoir.