In light of the increasing demand for oil and gas globally, efforts are drawn to boost production. Reducing CO2 emissions while providing the needed energy at the lowest costs becomes vital for a safe and secure future. With the continued technological development, CO2 foam injection has emerged as one of the much-needed technologies seeking to enhance oil recovery and can be used for carbon storage, which is useful in achieving decarbonization goals.
More about CO2 Foam Injection
Carbon dioxide injection refers to pushing the CO2 into the reservoir to increase the oil production by reducing oil viscosity and providing miscible or partially miscible displacement of the oil. CO2 enlarges the oil, therefore pushing it towards the producing well for extraction, GK Today stated.
A study published by Intechopen mentioned that the CO2 injection technique was started for EOR applications in the 1950s. However, it has been seen as impractical due to its low viscosity compared to formation fluids, leading to viscous fingering and an early breakthrough.
Then, polymer flooding emerged to reduce the mobility ratio of the displacing fluid to the displaced fluid. However, polymer flooding caused “formation damage due to physical adsorption of the high- molecular-weight polymer on the rock surface and mechanical trapping within the smaller-diameter pore throats.” After that, CO2 foam came out in the 1960s to replace the polymer seeking to avoid such formation damage.
CO2 Foam Efficiency
The article by Intechopen said that foam contains little water, which helped in reducing the formation damage, especially in water-sensitive formations and allows fast clean-up. Another article published by the National Center for Biotechnology Information (NCBI) elaborated that “foam injection can be considered as an effective way for gas channeling mitigation, mobility ratio modification, sweeping efficiency enhancement, and oil recovery increasing in the gas flooding process.” It has the ability to block high permeability areas as well as block water and gas in porous media.
According to the International Energy Agency (IEA)’s data about enhanced oil recovery (EOR) projects reported in April 2019, there are about 500,000 barrels of oil produced daily by using CO2 which represents around 20% of total oil production from EOR. During CO2- EOR, part of the injected CO2 stays under the ground. “If the CO2 that returns to the surface is separated and reinjected to form a closed loop, this results in permanent CO2 storage,” IEA stated. According to IEA data in 2019, between 300 kg CO2 and 600 kg CO2 are injected in EOR processes per barrel in the US.
Frontiers released an article about the benefits of enhanced oil recovery and CO2 sequestration that addressed a case study of injecting CO2 into three different wells. These scenarios included CO2 injection into the reservoir, CO2 injection into the aquifer, and CO2 injection into the aquifer followed by waterflooding. The three well configurations were considered; these configurations include all injectors and producers being drilled vertically, all wells being drilled horizontally, and vertical injectors and horizontal producers being used. By using the Computer Modeling Group software package, the following results were concluded: “The highest oil recovery of 73% of the original oil-in-place (OOIP) was obtained by injecting CO2 into the reservoir, utilizing vertical injectors and producers. During EOR treatments, around 7,928 tons of carbon dioxide can be sequestered in the reservoir/aquifer systems, on average.” Injecting CO2 into the water zone was very successful and enhanced the oil recovery by around 68–70% of the OOIP. Horizontal produces and injectors gave more oil.
“Overall, injection of CO2 into the depleted reservoir can provide dual benefits of CO2 sequestration and enhanced oil recovery.”