M Khazam, T Arebi, T Mahmoudi and M Froja
University of Tripoli, Libya
Scientific Tracks Abstracts: J Pet Environ Biotechnol
The minimum miscibility pressure (MMP) is one of the most important parameter to be determined in miscible gas injection projects to ensure and maximize the displacement sweep efficiency inside the reservoir. Usually the most effective way of determining the MMP is to run slim tube experiments. However, in the early screening stage, we often relay on the published empirical correlations to estimate the MMP and identify the most suitable candidates for the EOR gas injection projects. Also reliable estimation of the MMP helps the operator to develop injection conditions and to plan suitable surface facilities. In this paper, our main aim objective was to examine different published empirical CO2 MMP correlations using measured data mainly obtained from Libya and other published resources, and also to develop a new simple reliable correlation to be applied in the oil industry. The data collected covered a wide range of CO2 MMP (1544�??6244 psia) and oil API gravity (28-52ºAPI). Minitab regression tool was deeply used in our study and a wide range of new constructed correlations ranging from simple to complex ones were developed and statistically evaluated. Different PVT variables including Pb, T, API, γg, Rsi, molecular weight, volatile oil fraction, and intermediate oil fraction were considered in our study. The proposed simple CO2 MMP correlation is mainly function of the measured Pb, API, T, and Rsi and has very reliable degree of accuracy (SD=6.7%, RE =0.44%, AbsRE = 5.74%, R2 =95.22%) for the examined data. Also, this new correlation is more superior to all other industry published correlations that demonstrated an abs relative error ranges between 14.04% to 20.40% which are much higher percentage of error than our correlation and the standard deviation ranges between 14.67% to 29.52% which almost triple times of our correlation accuracy. The new correlation was validated against 100 measured PVT variables (Pb, Rsi, T & API) obtained from Libya, and the predicted CO2 MMP results have demonstrated very reliable trend (within the measured CO2 MMP trend) with no anomalies. Introducing more variables such as mole fraction of the light components and the molecular weight of the C7+ to the simple proposed correlation will add minor improvement to the accuracy, which supports the emphasis on adopting the simple correlation.