PREDICTION OF BUBBLEPOINT SOLUTION GAS/OIL RATIO IN THE ABSENCE OF A PVT ANALYSIS

Several published correlations used to estimate the bubblepoint pressure and the bubblepoint oil formation volume factor of reservoir oils require that the value of the bubblepoint solution gas/oil ratio be one of the input variables. Consequently, engineers resort to an additional correlation in order to estimate this value. The majority of the published bubblepoint solution gas/oil ratio correlations are functions of bubblepoint pressure and gas gravity, which can be obtained either experimentally (pressure-volume-temperature, PVT analysis) or estimated from the existing correlations. Thus, it is difficult to apply the correlations in the absence of a PVT analysis. In this study, a multiple regression analysis technique was applied to develop two novel correlations to estimate the bubblepoint solution gas/oil ratio and stock-tank vent gas/oil ratio in the absence of a PVT analysis. The developed correlations can be directly applied by using readily available field data, thus, forgoing the requirement of additional correlations or a PVT analysis. The bubblepoint solution gas/oil ratio correlation is related to the separator gas-oil ratio, to the separator pressure, and to the stock-tank oil specific gravity. However, separator pressure and temperature with the stock-tank oil specific gravity were the only independent variables used in stock-tank vent gas/oil ratio correlation. Another additional and important application of the proposed stock-tank vent gas/oil ratio correlation was to estimate the stock-tank vent gas flow rate