Author(s)

He Tang, Hao Chen, Xiansong Zhang, Baozhen Li

Corresponding Author

He Tang

ABSTRACT

CO2 has been studied for many years as a displacement agent for reservoir enhanced oil recovery. However, due to the difficulty of purification of CO2 and high purification costs, the use of impure CO2 flooding is often implemented in the field. Therefore, in this paper, to study the change of crude oil properties by injecting gas with different purity of CO2, based on the oil and gas of QHD29-2E oilfields, expansion tests and simulations were conducted to determine and simulate the saturated pressure, swelling factor, gas oil ratio(GOR), density and viscosity of CO2-crude oil under pure/impure conditions. Results show that under the same pressure, with the decrease of CO2 purity, the solubility of the injected gas decreases, the swelling factor decreases, and the viscosity reduction effect becomes worse. The intermediate component (C2-C6) in the impure CO2 can improve the dissolution, swelling and viscosity reduction of the crude oil by impure CO2 injection to some extent.

KEYWORDS

Impure CO2, gas oil ratio, expansion, viscosity reduction