Empirics prove – CCS can enhance oil extraction by removing carbon emitted.

Although oil and gas production has incompatibility with green and low-carbon development, synergy can be accomplished via technical advancement and scientific innovation. With the rapid development and large-scale application of carbon emission reduction technologies such as CCS and CCUS, the oil and gas industry will certainly be able to move toward a green future of low-carbon, efficient, and sustainable development while ensuring the safe supply of oil and gas.

In the oil and gas industry, CCUS provides more advantages than CCS. In applications, CCUS is a well-established system technology, with three parts: CO2 capture, utilization, and storage.

CO2 capture technology refers to the separation and collection of CO2 from industrial production or the separation of oxygen from the air for oxygen-enriched combustion to achieve the purpose of CO2 concentration, thereby reducing the difficulty in and energy consumption of capture. The CCUS fully integrated demonstration project of the Sinopec Shengli Oil Field branch, which can capture and store more than one million tons of CO2 per year, is planned to start up in 2022 (Hu et al., 2022). At present, there are mainly three methods of CO2 capture: oxygen-enriched combustion capture, postcombustion capture, and precombustion capture. Oxygen-enriched combustion capture burns the fuel with a high concentration of oxygen rather than air, followed by flue gas circulation, to create flue gas mostly made up of water and CO2, which is then processed with a flue gas cooling system to achieve a high concentration of CO2. Postcombustion capture is a more mature and widely used capture method. Precombustion capture is coupled with the integrated gasification combined cycle (IGCC) process.

As early as October 1996, the CO2 storage project in the Beihai Oil Field reached 100 × 104 t per year, with a planned total CO2 storage capacity of 2,000×104 for the whole project lifetime. At present, there are four feasible methods for CO2 storage. Geological storage refers to the permanent storage of CO2 injected directly into appropriate underground formations, and the formations suitable for CO2 injection include deep saline aquifers, depleted oil and gas fields, and basaltic aquifers.

In oil and gas production sites, CO2 utilization is the injection of collected CO2 into deep underground formations to improve the extraction of oil, natural gas, water, or other resources (Li et al., 2014; Nocito and Dibenedetto, 2019). CO2 utilization, particularly improved oil recovery, is still in industrial demonstration stages in China, with a significant gap compared with the world’s advanced level, whereas developed countries in Europe and America have established successful commercial systems.

In addition, the application of CCS and CCUS in the oil and gas industry also include supercritical CO2 fracturing and CO2 flooding. When compared to traditional hydraulic fracturing, supercritical CO2 fracturing has advantages such as reducing formation damage, utilizing CO2 to increase the complexity of the fracture network, and replacing adsorbed combustible gases, with the potential to increase oil and gas production, reduce water demand, and alleviate the environmental impact. CO2 flooding technology is an oil recovery method that replenishes formation energy in low-permeability reservoirs, boosting their development efficiency. It has been widely used in oil and gas operations, and it can also make a significant contribution to carbon emission reduction.