PREDICTION OF BUBBLEPOINT SOLUTION GAS/OIL RATIO IN THE ABSENCE OF A PVT ANALYSIS
S. Elmabrouk, E. Shirif
Abstract
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.
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