Study on multiple‐contact phase behavior in natural gas injection for enhanced oil recovery in Tarim Basin, China

Abstract

AbstractThe crude oil samples used in the study was from high‐pressure and high‐temperature (HPHT) reservoirs of Donghetang Oilfield in Tarim Basin in northwestern China. Crude oil–hydrocarbon gas multiple‐contact test and swelling tests are conducted to study the characteristics of phase behavior after hydrocarbon gas is injected into in the formation crude oil. The effect of different amounts of the injected hydrocarbon gas on saturation pressures of reservoir fluid is analyzed. The experimental results are regressed through PVTsim software. The authors use a state‐of‐the‐art HPHT pressure–volume–temperature (PVT) system to conduct the first contact miscibility pressure and swelling tests. Study results show that the multiple‐contact miscibility pressure is on the curve of saturation pressure of reservoir fluid versus the amount of injected gas. Furthermore, the first contact miscibility pressure is at the point of the curve where the tangent is zero. Multiple‐contact experiment is an important method for studying the mechanisms of miscible hydrocarbon gas flooding.