Research progress and prospects of reservoir engineering by CO2 flooding
CO2 capture,utilization,and storage(CCUS)can achieve a win-win situation of carbon emission reduction and oil pro-duction increase,and it is a key technology for the green and low-carbon transformation of the fossil energy industry.The petroleum and petrochemical industries have accelerated the large-scale application of CCUS technology after China proposed the goals of"peaking carbon emissions before 2030 and achieving carbon neutrality before 2060"in September 2020.It has gradually been re-vealed that CO2 flooding has contradictions such as a low impact,short effective time,and rapid increase in the gas-oil ratio in the field practices of SINOPEC Shengli Oilfield and CNPC Jilin Oilfield.It is necessary to strengthen the optimization design of reser-voir engineering further.This article systematically analyzed field practices of CO2 flooding to enhance oil recovery in sandstone res-ervoirs in China and abroad and key issues in the optimization design of reservoir engineering,such as the matching between reser-voir pressure maintenance level and miscible pressure,between well pattern direction and formation stress direction,between well spacing and reservoir permeability,and optimization of gas-water alternative displacement methods combined with the research re-sults of the million-ton CCUS demonstration project in Shengli Oilfield.Then,the article summarized the latest progress in reser-voir engineering research,such as reservoir pressure maintenance level during CO2 flooding,well network,well spacing,and gas-water alternative displacement,and analyzed the increasing pressure method,well pattern,well spacing,and gas-water alternative displacement optimization design for high-pressure miscible flooding.Finally,it indicated that the research direction of CO2 flood-ing reservoir engineering design should focus on the phase and flow laws of crude oil,CO2,and water in porous media under high-pressure conditions,the synergistic mechanism of CO2 flooding and storage,and the gas channeling mechanism of CO2 flooding un-der complex reservoir conditions.This article provides technical support for large-scale CO2 flooding in China.
CCUSCO2 floodingreservoir engineeringoptimization designdevelopment direction
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