Abstract
An effective parameter in the miscible-CO2 enhanced oil recovery procedure is the minimum miscibility pressure (MMP) defined as the lowest pressure that the oil in place and the injected gas into reservoir achieve miscibility at a given temperature. Flue gases released from power plants can provide an available source of CO2, which would otherwise be emitted to the atmosphere, for injection into a reservoir. However, the costs related to gas extraction from flue gases is potentially high. Hence, greater understanding the role of impurities in miscibility characteristics between CO2 and reservoir fluids helps to establish which impurities are tolerable and which are not. In this study, we simulate the effects of the impurities nitrogen (N2), methane (C1), ethane (C2) and propane (C3) on CO2 MMP. The simulation results reveal that, as an impurity, nitrogen increases CO2–oil MMP more so than methane. On the other hand, increasing the propane (C3) content can lead to a significant decrease in CO2 MMP, whereas varying the concentrations of ethane (C2) does not have a significant effect on the minimum miscibility pressure of reservoir crude oil and CO2 gas. The novel relationships established are particularly valuable in circumstances where MMP experimental data are not available.
Highlights
The life cycle of oil production from crude oil reservoirs involves three main stages: primary, secondary and tertiary
As there are no experimental data available for minimum miscibility pressure, it is appropriate to compare the MMP obtained by this simulation study with the results of Glaso (1985) and National Petroleum Council (NPC) (Klins 1984) based on the constraints of various correlations
The MMP simulation results for a 30° API reservoir crude oil (Iran) lead to the following conclusions: 1. PVT properties of the oil sample could be successfully estimated with high precision by applying the threeparameter Soave–Redlich–Kwong (SRK) equation of state and Lorenz–Bray–Clark (LBC) correlation
Summary
The life cycle of oil production from crude oil reservoirs involves three main stages: primary, secondary and tertiary. Reservoir-related forces, including gas cap expansion, aquifer expansion, dissolved gas expansion, rock and fluid expansion, gravity drainage, or a combination of these mechanisms provides sufficient energy to enable the oil to be produced through wellbores. The oil production rate decreases as the energy associated with these mechanisms decreases. Some secondary injection methods, mainly gas or water injection, are widely applied to help boost recovery as the impact of primary drive mechanisms decline. Primary and secondary recovery is typically responsible for recovering about 35% of the in situ reservoir oil (Chatterjee 2006). Enhanced oil recovery (EOR), when applied, are typically able to recover substantial additional oil from many reservoirs
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