| dc.description.abstract | Miscible gas flooding has recently overtaken to be the most successful enhanced oil
recovery technique. Carbon dioxide flooding is an integral part of miscible gas flooding.
This thesis focuses on the feasibility of the implementation of miscible CO2 flooding and
demonstrates the effects of different parameters, alongside alternative approaches to EOR
which my result in more incremental oil production.
To distinguish the miscibility of CO2 gas and oil, a key parameter of miscible CO2
flooding is the determination of the minimum miscibility pressure (MMP). MMP is the
minimum pressure at which the oil and injected gas achieve miscibility so that previously
trapped oil can be recovered. MMP can be determined in a variety of ways: through
experimental, analytical, and computational methods, as well as through other empirical
relationships. In common industry practice to define MMP, a series of carefully designed
slim tube tests is required. However, since slim tube testing is time-consuming and costly,
mathematical correlations are attractive, as they require few input parameters and little
information regarding the fluids and are quick and easy to use. This thesis develops a
more accurate MMP correlation for pure CO2 injection into high temperature reservoirs
by applying a series of 17 new MMP slim tube experiments, with the assistance of a large
database of slim tube MMPs that has been published in the literature.
Gas/oil interfacial tension (IFT) is seen as one of the most critical fluid characteristic
properties in oil reservoirs affecting gas injection production. Because IFT does not
appear in the flow equations directly, it would be difficult for the current commercial
reservoir simulator to capture its effect. Very few experimental data are available in the
literature on displacement involving a low IFT. However, those data were based on
synthetic oil not crude oil. This study evaluated the performance of miscible/near miscible
gases as a displacing fluid. The study investigated the feasibility of near-miscible CO2
application and improve our understanding of the mechanisms of near-miscible CO2
flooding by conducting a series of two-phase CO2 gas/oil core flood experiments under
reservoir condition in a carbonate core. Phase behaviour studies were carried out to
characterize the near miscible conditions. Slim tube and swelling/extraction tests were
performed to identify the near miscible range and eliminate mass transfer mechanisms to
create phase equilibrium for the displaced fluid/fluid flow in porous media. The study's overall results indicate that near miscible could achieve the same ultimate oil
recovery as miscible condition. This outcome will define a new strategy when applying
CO2 gas injection hence economical in terms of compression costs.
Reliable relative permeability curves of oil/gas systems are important for the successful
simulation and modelling of gas injections, especially when the miscibility condition
approaches. In this study, a series of relative permeability were obtained by history match
the experiential data at different IFT level (immiscible, intermediate, and near miscible).
To investigate the IFT scaling effect on gas/oil relative permeability. The results shows
that the relative permeability of both gas and oil increase as the IFT decreases, but not
equally. As the system moves from immiscible toward miscible conditions, the relative
permeability increases, and its curvature reduces but does not achieve straight crossline.
Finally in This thesis, will demonstrate the two different approaches in modeling miscible
gas injection utilizing compositional and extended black oil model. Fully compositional
model is complex and required a lot of information. Extended black oil simulation is an
alternative approach to compositional simulation and provides an engineering tool to
account for oil displacement by a miscible or immiscible fluid. the result shows that using
EOS to obtain for MCM Miscible CO2 indicate that excellent prediction to experimental
data at 1-D simulation. However, utilizing the ultra-low relative permeability for
predicting the miscible displacement has shown promising results in terms of the ultimate
oil recovery, this new approach would allow the performance of miscible displacement
to by predicted utilizing the black oil model. | en |
