Field Practice of Carbon Dioxide Huff and Puff in Bottom Water Heavy Oil Reservoirs of the Sixth District of Gangxi Oilfield

The heavy oil reservoirs in the sixth district of Gangxi Oilfield, with active bottom water, has serious problems of bottom water coning in the development, resulting in uneven movement of the oil formation in plane and longitudinal directions and low recovery rate. Scholars at home and abroad proposed a recovery technology that uses CO2 huff and puff to control water pressure cone and improve the development effect of heavy oil reservoirs in bottom water. To further prove the applicability of this technology, a small-scale mine trial of CO2 huff and puff to increase production in heavy oil reservoirs with bottom water has been conducted in Gangxi Oilfield, and the production increase effect of single well was obvious, which clarified the major controlling factors of the CO2 huff and puff control water stimulation effect. In this paper, based on the current geological reservoir status of the heavy oil reservoir in the sixth district of Gangxi Oilfield, the main control parameters affecting the huff and puff effect, including the CO2 injection volume, injection rate, injection pressure and well staging time, were optimized, and implements a larger-scale CO2 huff and puff and production increase measure. The results of the field implementation confirm that CO2 huff and puff can cooperate with bottom water to increase the elastic driving capacity of the formation, reduce the viscosity of crude oil, inhibit the cone of bottom water, and improve the oil drive efficiency of heavy oil reservoirs. This paper’s research results can be applied to guide similar reservoirs to adjust their development plans and implement CO2 huff and puff to improve the effectiveness of development and enhance the recovery rate. At the same time, CO2 huff and puff technology can also contribute to China’s goal of “carbon peak and carbon neutrality”.