Experimental study on enhanced oil recovery by multiple thermal fluid flooding in mid-deep heavy oil reservoirs

Multiple thermal fluid mainly consists of steam, N-2 and CO2 and is a new heat-carrier introduced into the petroleum reservoir development in recent years, which is more suitable for the development of mid-deep heavy oil reservoirs. In this paper, the PVT tests under different conditions were carried out to research the properties of heavy oil-CO2/N-2 system. Then, a series of 3D simulation experiments were conducted, including steam flooding experiment, multiple thermal fluid flooding experiments and steam flooding to multiple thermal fluid flooding experiments, to analyse the production characteristics of multiple thermal fluid flooding and optimise the gas-water ratio of multiple thermal fluid flooding. Finally, the best way to develop mid-deep heavy oil reservoirs was discussed, according to the production characteristics of steam flooding and multiple thermal fluid flooding. This study provided a feasible way to development mid-deep heavy oil reservoirs with multiple thermal fluid. [Received: February 18, 2020; Accepted: January 10, 2021]