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This paper seeks to overcome the shortcomings of previous correlation work on PVT. More than a hundred oil samples were PVT. More than a hundred oil samples were collected from three major oil producing countries in Africa — Libya (97 samples), Nigeria (27), and Angola (4). PVT data on samples analyzed and correlations established. Equations were developed using multiple regression analysis to predict the saturation pressure, the solution gas-oil ratio, and the pressure, the solution gas-oil ratio, and the chemical composition of oil reservoir fluids in the three countries. A new equation was developed for estimating gas gravity, which eliminates the need to know the gas gravity for predicting saturation pressure. predicting saturation pressure. The developed correlations are functions of easily measurable field data such as first-stage separator pressure and temperature, producing gas-oil ratio, stock-tank oil gravity, and reservoir pressure and temperature. They were found to adequately fit with random PVT data in the available literature and to be more practical and accurate than other techniques such as those used by Standing Glaso, and Vasquez. Moreover, they may be applied to other geographical areas.
The saturation pressure is determined in the PVT laboratory from pressure-volume relationships. However, if a PVT analysis is not conducted, the bubble-point pressure can be estimated from well-known correlations available in the literature. Unfortunately the aforementioned correlations are not functions of easily measurable field data. The Standing and Laster correlations are based on total gas-oil ratio and total gas gravity and they relate to a specific geographical area. The total gas-oil ratio and total gas gravity cannot be obtained directly from production tests. In order to evaluate them, one should already have PVT analyses. In addition, Standing's correlations when applied to different geographical areas such as Brazil and the North Sea, resulted in different equations from those of Standing. These drawbacks reduce the universal application of Standing's correlations. Glaso developed a correlation based on Standing's assumptions but used average gas gravity instead of total gas gravity. He also introduced corrections for the paraffinity to account for the differences in the oil base. However, his work still has the drawback of using total gas-oil ratio and the need for chemical composition.
