This study evaluates reservoir and reservoir fluid parameters relevant to CO2 flooding to enhance hydrocarbon recovery from an Ordos's Basin oilfield located in Northwest China.
Field M is a tight sandstone reservoir containing light and low viscosity oil.CO2 could be available from a power plant and a coal refining factory nearby. Laboratory experiments were conducted for the purpose of determining the crude oil MMP with CO2 and oil PVT properties. The MMP of CO2 flooding was determined through slimtube test and calculation of PR3- equation. In addition, the utilization factor of CO2 injected to oil was calculated at MMP with pure CO2, and the sequestration potential of CO2 in field M was calculated with the sequestration coefficient multiplying recoverable reserves. We also quoted the methods mentioned in the Carbon sequestration Leadership Forum to calculate the sequestration potential of Field M. Finally, we draw a contrast among the predictive sequestration CO2 results, and the contrast show that applying the sequestration coefficient to evaluate the CO2 sequestration potential of field M is reasonable and reliable.
As a major role of greenhouse gasses, carbon dioxide (CO2) generated from human beings activities is seriously resulting in air pollution, global warming, and threatening the environment safety and people's health -. How to effectively implement geological sequestration of CO2, which is one of the most useful means to mitigate greenhouse gas emission, is becoming a public issue for scientists to focus on(Bachu S et al.,2002,2003).
For CO2 geological sequestration, formations like oil and gas reservoirs, deep saline aquifers, and coal beds are available. Not only could geological sequestration of CO2 in reduce greenhouse gas emission, also in EOR, scientists are seeking more effective ways to utilize CO2 for EOR of oil and gas reservoirs in the world. Generally, CO2 sequestrating in oil and gas reservoirs is most economical and reliable for countries (Bradshaw J et al.,2005,2007,2008, Stevens S H et al.,1999, Bachu S et al.,2004, Kovseek A R.2003).
Chinese government is dedicating to reduce CO2 emission and trying to utilize it as a resource (Liao Xinwei,2011). From 2006 to 2011, China Ministry of Science and Technology has supported a series of projects to reduce CO2 emission: such as the National Fundamental Research Program—"Research on Utilizing Greenhouse Gas as a Resource for EOR and Geological Storage" (2006) (Authorized CNPC to undertake); "Pilot test of CO2-EOR and CO2 Storage in Jilin Oil Field" (2007) (Authorized CNPC to undertake); "CO2 Capture and Storage for EOR" (2008). In 2011, Chinese National Fundamental Research Program ("973 and 863 programs") and Chinese National Major Science and Technology Projects have been approved to carry out continually, and a lot of successes have been achieved in these projects.
Studies for assessment of CO2 flooding and sequestration have already been taken in Changqing oil field, Ordos Basin, northwest China to enhance EOR in low porosity and low permeability reservoirs there. Oil viscosity from reservoir M there is 1.35mPa.s under reservoir condition, and MMP is 19.8MPa (lower than oil reservoir pressure 22MPa), all of which could be suitable for CO2 flooding. This paper presents the achievements from the experiments making an assessment of CO2 flood for EOR and sequestration benefits in Ordos Basin, Northwest China. Based on the evaluation of reservoir M, a foundation for further research on CO2 flooding and sequestration and for further implement have been set up.