Cyclic Gas Injection in Low-Permeability Oil Reservoirs: Progress in Modeling and Experiments

Cyclic gas injection effectively enhances oil recovery for low-permeability oil reservoirs. Numerous theoretical, mathematical, and laboratory investigations have attempted to unlock underlying recovery mechanisms and optimal design for the cyclic gas injection in these reservoirs. While these investigations have shed light on various aspects of the process, different descriptions of key recovery mechanisms and optimal design parameters can be found in the literature. Many of these published studies consider conventional approaches and concepts, such as assuming advection-dominated fluid flow and mixing between injected gas and oil within the matrix, to simulate the process or conduct experiments. Under different reservoir and operational conditions, to be reviewed, one or a combination of mechanisms can be responsible for improving oil recovery. This review aims to critically examine the published modeling and experimental studies regarding the recovery mechanisms of gas cyclic injection and the conditions under which the process can enhance oil recovery. The review will identify lessons learned and areas in need of further research.