Empirical PVT correlations for Colombian crude oils

Abstract

Empirical PVT correlations are presented for estimating bubble-point pressure, solution gas-oil ratio, oil formation volume factor, and isothermal compressibility. To develop the above correlations, the data base consisted of ninety-eight PVT laboratory analyses for Colombian crude oils. The gas-oil ratios, gas gravities, oil gravities, and formation volume factors involved in the development of the correlations are the result of one, two and three-stage flash separation as recorded from PVT samples analyzed in the laboratory. The effect of separator conditions on the prediction of the bubble-point pressure, solution gas-oil ratio and oil formation volume factor is studied. A new correlation that corrects the separator solution gas-oil ratio for separator conditions is provided. Improved correlations for estimating the bubble-point pressure, based on the corrected separator solution gas-oil ratio, are developed. In addition, total solution gas-oil ratio and oil formation volume factor correlations based on separator data are presented. Since the stock-tank gas-oil ratio and stock-tank gas gravity are not usually measured in the field, these correlations represent a realistic form of estimating PVT properties. Although the correlations presented are based on Colombian crude oils and gases, consideration should be given to their applicability to all types of gas/oil mixtures with "API gravities ranging between 18 to 44.9 (single stage separation), 14.3 to 29.0 (two stage separation) and 40.3 to 44.1 (three stage separation).