PVT Correlations for Trinidad Oil Offshore the South West Coast

Abstract

Reservoir fluid properties such as bubble point pressure, oil formation volume factor and solution gas-oil ratio are used for the evaluation of reservoir performance and reserves estimation. Laboratory analyses of these properties are not always available and they are best estimated from correlations. The available correlations were developed for both worldwide applications or for specific regions since oil from different regions vary in compositions. In this study correlations by Standing, Vasquez and Beggs, Glaso, Al-Marhoun, Petrosky and Farshad and Velarde et al. were tested to estimate the above mentioned PVT data for Trinidad oils offshore the Southwest Coast. A spread sheet was developed for the calculations and the data for the evaluations were taken from twelve PVT reports.

The results show that the Velarde et al correlations gave the best estimate of the aforementioned PVT data for the twelve available PVT data sets. A comparison of the estimated and experimental PVT data show differences of less than ± 7.0 % for bubble point pressures, less than ± 4.0 percent for oil formation volume factors and less than ± 10.0 percent for solution gas oil ratios. These results indicate that the Velarde et al. correlations can be used to obtain accurate estimation of the above PVT properties for Trinidad oils offshore the Southwest Coast for future reservoir engineering calculations. The Verlade et al correlation was developed for worldwide application and its suitability to predict PVT data for a region should be tested prior to the development of new correlations.

Key words: PVT Correlations; Oil; Bubble-point pressure; Oil  formation volume  factor; Solution gas-oil ratio; Trinidad