Prediction of Bubblepoint Pressure and Bubblepoint Oil Formation Volume Factor in the Absence of PVT Analysis

Abstract

Up till now, there has not been one specific correlation published to directly estimate the bubblepoint pressure in the absence of PVT analysis and, at the moment, there is just one published correlation available to estimate the bubblepoint oil FVF directly in the absence of PVT analysis. The majority of the published bubblepoint pressure and bubblepoint oil FVF correlations cannot be applied directly. This is because the correlations require the knowledge of bubblepoint solution GOR and gas specific gravity as part of the input variables, both of which are rarely measured field parameters. Solution GOR and gas specific gravity can be obtained either experimentally or estimated from correlations. In this study, multiple regression analysis technique is applied in order to develop two novel correlations with which to estimate the bubblepoint pressure and the bubblepoint oil FVF. These new correlations can be applied in a straightforward manner by using direct field data. Additional correlations or experimental analyses are unnecessary. Separator GOR, separator pressure, stock-tank oil gravity and reservoir temperature are the only key parameters required to predict bubblepoint pressure and bubblepoint oil FVF using the proposed correlations. IntroductionReservoir fluid studies are essentially based on pressure-volume-temperature (PVT) analysis. This analysis consists of a series of laboratory procedures designed to provide the values of the reservoir fluid properties required in material balance calculations, well test analysis, reserves estimates, inflow performance calculations, and numerical reservoir simulation. Ideally, reservoir fluid properties are determined from laboratory studies on live oil samples collected from the bottom of the wellbore or from the surface. Standard reservoir PVT fluid studies are designed to simulate the simultaneous fluid flow of oil and gas from the reservoir to the surface. The production path of reservoir fluids from the reservoir to surface is simulated in the laboratory at reservoir temperature. During this process, the bubblepoint pressure (p b ) is measured. Likewise, the oil volumes and the amount of gas released are measured and used to determine oil FVF (B o ) and solution GOR (R s ) as functions of pressure.

Evaluating the Effect of New Gas Solubility and Bubble Point Pressure Models on PVT Parameters and Optimizing Injected Gas Rate in Gas-Lift Dual Gradient Drilling

“…There have been many studies on various methods for obtaining the bubble point pressure in the published literature, but there has not been an organized study on "comparing the performance of various models in obtaining the bubble point pressure in dual gradient gas drilling", and therefore, it would be suggested as a topic for future research. The aforementioned existing studies have covered such aspects as reviewing the correlations of the bubble point pressure and oil formation volume factor [46], novel empirical correlations for estimation of bubble point pressure [47], prediction of bubble point pressure, and bubble point oil formation volume factor in the absence of PVT analysis [48], comparing bubble point pressure of irreverent, crude oils [49], application of artificial intelligence techniques [50], and adopting the technique of Boosting ensembles [51]. However, the reason for selecting the Drift Flux model in the present study was that it is one of the widely-used models in two-phase drilling projects and enables obtaining a high calculation speed and a high precision.…”

“…Figure 12 summarizes the general advantages, limitations, and also future extensions of the present study in a concise form. point pressure [47], prediction of bubble point pressure, and bubble point oil formation volume factor in the absence of PVT analysis [48], comparing bubble point pressure of irreverent, crude oils [49], application of artificial intelligence techniques [50], and adopting the technique of Boosting ensembles [51]. However, the reason for selecting the Drift Flux model in the present study was that it is one of the widely-used models in two-phase drilling projects and enables obtaining a high calculation speed and a high precision.…”