Carbon capture tech makes oilfield go greener

Oil reserves in this area are 3.58 million tons, with the majority being heavy crude oil, which is difficult to extract. Through the operation of the CCUS cyclic injection station, not only has the carbon dioxide emissions problem been solved, but the extraction efficiency has also been increased from around 10 percent to 40 percent, Wang said.

Oil exists in different forms at different depths underground, and different geological conditions and oil states require different extraction methods. For example, in some areas, oil can be directly extracted. While in others, water injection is needed. In areas where rock formations have high density and low permeability, such as low permeable oil layers, gas injection is required to aid in oil recovery.

"The concrete floor we are standing on has high density, and it is difficult for water to pass through it. When the underground rock formations that contain oil have high density, injecting high-pressure gases like carbon dioxide can help to force out the oil stored in the formations and increase the extraction rate," Wang said.

Construction began for the CCUS cyclic injection station in the 229 Block in March last year. Since its completion in December, over 40,000 tons of carbon dioxide have been injected underground, leading to an increase of over 6,000 tons in oil production.

Liang explained that in recent years, nearly 80 percent of new geological reserves in the Liaohe region are special lithological oil reservoirs such as tight oil and shale oil, which have a large oil expansion rate and low permeability. Their carbon absorption capacity is three to four times that of water, and it has been confirmed that carbon dioxide has a significant oil displacement and energy supplementation effect, as well as good viscosity reduction effect.

It is estimated that there are 262 potential blocks suitable for CCUS applications in the Liaohe area, with a carbon storage capacity of over 200 million tons, making it a natural large carbon storage facility.

Luan Ruizhi, director of the CCUS project department at the Oilfield Technology Research Institute, said Liaohe Oilfield has the deepest burial and the most diverse types of CCUS projects in the country, which means that some problems have no domestic solutions and must be resolved independently.