Research on High Temperature Compound Gas Drive Oil Displacement Mechanism for Heavy Oil Reservoirs

摘要

Based on the analysis of the viscosity-temperature characteristics and rheological characteristics of heavy oil, this paper systematicaly investigates seepage characteristics and oil displacement mechanism of exploiting heavy oil by steam drive and high temperature compound gas drive. The experimental results indicate that, according to the displacement efficiency from strong to weak, each displacement method can be ranked as following: compound gas (steam,N2 and CO2) drive, compound gas(steam and N2) drive, compound gas (steam and CO2) drive, steam drive. The main stimulation mechanism of high temperature compound gas drive is to reduce viscosity by heating, to improve the sweep efficiency, to improve oil phase permeability and oil-water mobility ratio, to maintain and enhance formation pressure, to expand heavy oil volume and so on. The results of this research provide theoretical criterion for application of high temperature compound gas drive in heavy oil field.