The Injection of CO2 in Displacement of Reservoir Oil
To improve extraction of oil, there are techniques used to enhance oil recovery in reservoirs. Gas introduction is the most commonly employed technique, whereby carbon dioxide or nitrogen is introduced into the basin to expand and push extra oil to the nearest fabrication well bore. The injected CO2 lowers the thickness oil and thus progresses its gush velocity. The other important thing is that the injected carbon dioxide swells the crude oil and lowers the interfacial tension between the oil and CO2, and oil phase in the near miscible areas.
The Problems in Inoculation of CO2 in Disarticulation of Basin-Oil
One of the main challenges in the introduction of CO2 concerns basin force required to uphold the produced miscibility. This is because pressure range from about 1150 psi for the carbon dioxide to about 4900 psi for the augmented pressure (Satter 465). In essence, the core issue related to hydro-carbonation miscible flooding concerns poor vertical and horizontal sweep effectiveness based on viscous fingering. In this regard, large volumes of carbon dioxide are expensive and required greatly, but the gas solvent may be trapped inside and prove difficult to or impossible to recover (recycle to reduce costs). It is also significant to point out that huge outlays are sustained in acquiring carbon dioxide, but the end result of augmenting oil recovery causes a problem. This implies that there is relatively marginal contribution in regards to total oil recovered in countries like Canada and the U.S. In contemporary terms, CO2 offers about 279000 containers of oil every day depicting about 4.9 percent of the overall US rudimentary oil fabrication (Rafiqul 187). Recent carbon dioxide flooding has been so expertly and financially attractive that carbon dioxide supply rather than price has been the constraining developmental aspect. In accord, CO2 flooding is carried out by introducing huge quantities of CO2 up to fifteen percent of the hydrocarbon pore amount into the reservoir. In typical terms, it takes about ten Mcf of carbon dioxide to recover a single incremental barrel of oil.
An early breakthrough of carbon dioxide leads to numerous issues that comprise corrosion in producing wells. They carbon dioxide presence also poses the issue of separating it from saleable hydrocarbon, which calls for repressing of carbon dioxide for recycling. The added major problem involves augmented obligation of CO2 in each incremental barrel produced. There is a huge problem in regard to the method that can be used to overcome carbon dioxide miscible procedure constraint and functional issues (sweep effectiveness, unfavorable injectivity profiles, augmented ratios of carbon dioxide to oil produced, as well as gravity override) (Islam 300). It is difficult to recognize and implement affordable and effective carbon dioxide thickeners that would have allowed augment in the viscosity of carbon dioxide. This is also as a result of lack of precision to allow careful regulation of the augment in viscosity of carbon dioxide. Moreover, the possible alternative to this is carbon dioxide soluble thickener composed of brine and crude oil insoluble. However, this presents a challenge since it is bound to inhibit partitioning into other fluid phases and its subsequent absorption onto the reservoir rock. It is also challenging to have an efficient blueprint of carbon dioxide foams for mobility decrease, especially for high temperature reservoirs where chemical degradation of surfactants is of great concern.
The Displacement Differences in Injection of CO2 in Displacement of Reservoir Oil
The technique of gas
injection displacement comprises miscible flooding, oil volume swelling, and viscosity
reduction. Therefore, preliminary reservoir pressure of a sub reservoir is lower
than the minimum miscible pressure. This is in regard to related gas injection
and that is augmented than minimum miscible pressure as a result of carbon dioxide
(CO2) injection. This implies that the dislocation technique of
related chatter inoculation in a sub reservoir is immiscible deluging and that
of CO2 inoculation is ‘miscible
flooding.’ CO2-water alternate ‘miscible flooding’ is the most efficient manner or technique to
enhance revitalization (Dipietro et al 48). At this point, its recovery is
augmented than water flooding, carbon dioxide CO2 miscible flooding,
and related gas-water alternative immiscible flooding. Hence, related gas water
alternative immiscible flooding can also enhance recovery since gas injection
has the impact of distension and it also depicts viscosity lessening as a result
of this process. The other thing concerns the recovery of carbon dioxide, CO2,
and this occurs when water alternate miscible flooding after flooding is
fundamentally the same with merely carbon dioxide, CO2 wateralternative
miscible flooding carbon dioxide- water alternative miscible flooding. This
occurs following related gas- water immiscible flooding that has no apparent impact
in enhancing recovery. As such, this is
centered on the reason that mobility of related gas is augmented in sufficient
levels to result in finger advance and hence form preponderance flow path. The resultant
injected carbon dioxide flows only along this flow path and it would not sweep
more residual oil.
Dipietro et al, “The Role of Naturally-Occurring CO2 Deposits in the Emergence of CO2 Enhanced Oil Recovery.” Retrieved from: http://co2conference.net/pdf/1.2-Slides_DiPietroCO2Sources2011-CO2FloodingConf.
Islam, Rafiq. Greening of Petroleum Operations: The Science of Sustainable Energy Production. New York, NY: John Wiley & Sons, 2011.
Rafiqul, Islam. Unconventional Gas Reservoirs: Evaluation, Appraisal, and Development. Boston: Elsevier, 2014.
Satter, Abdus. Practical Enhanced Reservoir Engineering: Assisted with Simulation Software. Washington, DC: PennWell Books, 2008.