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Abstract
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.
Introduction
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 [1]-[2]. 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.
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