Research on heterogeneous compound flooding system based on dispersed particle gel

Abstract

Aiming at addressing the problem that the remaining oil maintains wide distribution after polymer flooding and the existing chemical compound flooding systems lack extensive application, a heterogeneous compound flooding system based on dispersed particle gel (DPG) is proposed as an alternative technology for enhanced recovery after polymer flood-ing. This study designs and characterizes the heterogeneous compound flooding system, as well as its impact factors, and field trial performances. With the systematic viscosity and oil-water interfacial tension as evaluation indicators, the field trial performance of the heterogeneous polymer flooding system is optimized and evaluated based on DPG. The results show that the systematic viscosity is 12.1 to 17.3 mPa·s while the interfacial tension keeps constant at 10−3 mN/m magnitude. At 80◦ C, with 60 days aging, the viscosity retention ratio of the system is over 83.5%, and the interfacial tension between oil and water is still maintained at 10−3 mN/m. The results of core flooding experiment show that the heterogeneous compound flooding system exhibits good injection performance, moving characteristics of plugging, breakthrough migration and re-plugging. After high-temperature aging, subsequent water flooding still sustains at high pressure with high resistance to erosion. Through the selective high and low permeability layers, the water injection profile is improved, and eventually oil recovery is enhanced to 20.61% after polymer flooding.