A dynamic control strategy for improving combustion chamber sweep efficiency during the in-situ combustion

Combustion chamber extension is closely associated with oil production efficiency and ultimate oil recovery during in-situ combustion (ISC) process. However, the effective method for controlling combustion chamber extension is is still being explored. This work proposes a novel measure to modify the unfavorable expansion behaviors of combustion chamber while minimizing the impact on variations in pressure difference and combustion stability, and it is implemented by the production well intermittent shutdown (PWIS) method in the heterogeneous porous medium. The variation of effluent gas compositions, spatial distribution of coke zone, swept area of combustion chamber, burning stability, and pressure difference are studied. The results show that the combustion chamber and coke zone develop uniformly and their expansion volume in low and medium permeability regions enlarge noticeably with the PWIS implementation. The PWIS method is able to modify the unfavorable expansion behaviors of combustion chamber with little influence on the burning state, especially as the combustion front propagated in the central section between the injector and producer. The final oil recovery factor can be enhanced by 73.8% after implementing the PWIS method. This work is of significance to the ISC field application and provides an approach to achieving a higher volumetric sweep efficiency of combustion chamber.