CO2 Near-Miscible Flooding Research
Research: CO2
Near-Miscible Flooding
Near Miscible CO2 Application to Improve Oil Recovery for
Small Producers
Carbon dioxide (CO
2) injection for enhanced oil
recovery is a proven technology. It is also considered as one
of the most promising methods for carbon sequestration in geologic
formations. CO
2 injections are normally operated
at a pressure above the minimum miscibility pressure (MMP), which is
determined by crude oil composition and reservoir conditions. However,
many reservoirs in the United States and around the world are at
shallow depths or geologic conditions exist such that they operate at
pressures below the MMP. The goal of this project is to demonstrate
near miscible CO
2 application can substantially
increase oil productions with CO
2 injection at
pressures below MMP. The application of CO
2
injection at near miscible conditions may lead to development of CO
2
projects for small producers in reservoirs where the MMP is not
attainable at current operating reservoir pressures.
When CO
2 injection operates at a pressure below
the MMP, displacement efficiency decreases as a result of the loss of
miscibility. Near miscible displacement generally refers to
the process occurring at displacement pressures below the MMP, but the
actual pressure range has never been clearly defined. At
displacement pressures near miscible, significant oil recovery has been
observed in slim-tube experiments and to a lesser extent in core tests.
This better recovery has been attributed to possible improvement of the
mobility ratio in the displacement and an extraction process, both of
which are closely related to operating pressure. To increase
the resource base for CO
2 flooding and
substantially increase the production from reservoirs operated by small
producers, it is proposed to investigate the feasibility of applying CO
2
displacement at near miscible pressures by conducting appropriate
experimental work and reservoir simulation.
The project includes both experimental and computational
studies. In the experimental study, work will 1)
systematically characterize the near miscible condition and study
recovery of waterflood residual oil using CO
2
displacement at near miscible pressures, and 2) identify key parameters
in phase behavior and flow tests for simulation modeling.
In the computational study, the work will 1) develop a representative
model to simulate near miscible displacement physics and 2) assess the
potential of recovery processes at near miscible pressures.
This project is a joint effort by the Tertiary Oil Recovery Project
(TORP) at the University of Kansas and Carmen Schmitt, Inc. (Kansas
independent producer). The successful completion of this feasibility
study will lead to future field demonstration pilots in producing areas
operated by our project partner in the Arbuckle formation. The
potential benefits will be significant with an increase in the resource
base for CO
2 flooding and an expanded
opportunity for small producers to apply CO
2
flooding.
This project is funded by
RPSEA under the Unconventional Onshore & Small Producer Program. The Principal Investigator is Dr.
Jyun-Syung Tsau, and graduate students are Ly Huong Bui and WoanJing
Teh.
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CO2 flooding and sequestration
