In the quest to boost oil recovery and reduce carbon emissions, a groundbreaking study has emerged from the collaboration between Sinopec Carbon Industry Technology Co., Ltd. and the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation at Southwest Petroleum University. Led by CHEN Jun and his team, the research delves into the potential of CO2 huff-n-puff technology in shale oil reservoirs, offering promising insights for the energy sector.
Shale oil reservoirs often face rapid production decline and low recovery rates, posing significant challenges to energy companies. Traditional waterflooding methods have proven less effective compared to CO2 injection, which boasts superior injectivity and miscibility with crude oil. “CO2 huff-n-puff not only enhances oil recovery but also addresses carbon sequestration, making it a win-win scenario for the industry and the environment,” explains CHEN Jun, the lead author of the study published in *Evaluation and Development of Petroleum Reservoirs*.
The study employed advanced numerical simulation techniques to model the formation and distribution of hydraulic fractures, integrating logging data, geological parameters, and fracturing operation data. By establishing a composite discrete fracture network numerical model, the researchers analyzed the oil recovery enhancement mechanisms of CO2 huff-n-puff. The findings revealed that CO2 injection restores production capacity by replenishing formation energy, extracting light and intermediate components from shale oil, and leveraging CO2 diffusion, oil viscosity reduction, and expansion effects.
One of the key discoveries was the optimal injection strategy for a single well, which includes initiating when daily oil production declines to just above 8 cubic meters, injecting 15,000 to 24,000 tons of CO2 at a rate of 500 to 900 tons per day, a shut-in duration of 30 to 50 days, and conducting 2 to 3 huff-n-puff cycles. Among the reservoir engineering parameters, injection volume was identified as the primary factor, with a weight of 0.48.
The implications of this research are substantial for the energy sector. By optimizing CO2 huff-n-puff techniques, companies can enhance oil recovery rates, extend the productive life of shale oil wells, and contribute to carbon emission reduction. “This study provides technical guidance and evaluation support for the implementation of Carbon Capture, Utilization, and Storage (CCUS) technology in shale oil reservoirs,” says WANG Haimei, a co-author of the study.
As the energy industry continues to seek innovative solutions for sustainable development, this research offers a compelling case for the adoption of CO2 huff-n-puff technology. By bridging the gap between enhanced oil recovery and carbon sequestration, the study paves the way for a more efficient and environmentally friendly approach to shale oil extraction. The findings not only offer immediate practical applications but also set the stage for future advancements in the field, potentially reshaping the landscape of oil and gas production.