Research and Application of Bottom Water Control and Suppression Technology by CO2 Huff-and-Puff

In order to solve the problems about rapid increasement rate of water cut and large production decline in bottom water heavy oil reservoir due to active bottom water and high crude oil viscosity, the research on CO2 huff-and-puff technology is carried out. The results showed that the mechanism of CO2 huff-and-puff was mainly to reduce the viscosity of heavy crude oil, carbonate reacted with bottom water and formed interlayer to achieve viscosity reduction and precipitation. The comprehensive water cut was decreased by 35%, and the average oil production of a single well was increased by 3∼4 times. Therefore, CO2 huff-and-puff technology was one of technologies about bottom water control and oil production stabilization, and it is of great significance to enhance oil production in heavy oil bottom water reservoirs.