Abstract
CO2 geo-sequestration, as an effective method to reduce Green House Gas emissions, is a front subject in China. In order to identify the potentials of implementing large scale CO2 sequestration projects according to China's current development tendency, this paper analyzes the general formation conditions of the main oilfields in China, which are manifested in complex formation structure with strong heterogeneity, low or ultra-low permeability and low porosity.
In China, the main application mode of CO2 sequestration, also the most profitable method, is to inject CO2 into oil and gas reservoirs to enhance recovery. Meanwhile, 60%-80% of the injected CO2 could be stored into the formation. Jilin oilfield in northeast of China, the dominant test field for CO2 sequestration, has been listed into the National Key Program in 2006. Pilot tests reveals formation here is featured with well developed sand body, good connectivity, well defined cap rock, undeveloped fractures, and independent hydro-geological system, which contribute to a considerable and secured storage for CO2. Though still on the initial stage, studies here would shed light on the further researches in China.
Some unique advantages of conducting CO2 sequestration projects in China have been summarized and analyzed in this work too. Most of the new-found oil and gas reservoirs belong to low-permeability reservoirs, wherein CO2 flooding shows its superiority over conventional water injection in tight formations. Moreover, both main CO2 sources (coal-fired plants & power plants) and injecting sites(low-permeability reservoirs) locate in northern and eastern China, which would meet the demand of CO2-EOR and shorten the distance of transportation to reduce corrosion risk and operation cost. Although being not regulated by Kyoto Protocol, positive measures of CO2 sequestration in China possesses a significant and far-reaching meaning to releive the pressure of global environment.
