Bubblepoint Oil Formation Volume Factor Research Articles

The Prediction of Bubble-point Pressure and Bubble-point Oil Formation Volume Factor in the Absence of PVT Analysis

Up to now, there has not been one specific correlation published to directly estimate the bubble-point pressure in the absence of pressure-volume-temperature (PVT) analysis. Presently, there is just one published correlation available to estimate the bubble-point oil formation volume factor (FVF) directly in the absence of PVT analysis. Multiple regression analysis technique is applied to develop two novel correlations to estimate the bubble-point pressure and the bubble-point oil FVF. The developed correlations can be applied in a straightforward manner by using direct field measurement data. Separator gas oil ratio, separator pressure, stock-tank oil gravity, and reservoir temperature are the only key parameters required to predict bubble-point pressure and bubble-point oil FVF.

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-volumetemperature, 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 stocktank 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 stocktank vent gas/oil ratio correlation. Another additional and important application of the proposed stocktank vent gas/oil ratio correlation was to estimate the stock-tank vent gas flow rate.

Assessment Of Bubblepoint Oil Formation Volume Factor Empirical PVT Correlations

The oil formation volume factor (FVF) among other factors is the most important factor that enables the calculation of the amount of reserves in a particular reservoir. In this paper, the existing oil formation volume factor correlations were assessed for their performance using data from the Niger Delta Region. Two hundred and fifty PVT reports were validated for this study from various oil fields. Both quantitative and qualitative analytical methods were implemented through statistical parameters and performance plots respectively. From the general evaluation i.e. using the full range of the data, Hemmati and Kharrat (2007) correlation performed the best for the Niger Delta crude with percent mean absolute relative error (Ea) of 1.9055 and correlation coefficient (r) of 0.9897. From the oil API gravity ranges reliabilityanalysis, it is clear that different correlations other than Hemmati and Kharrat (2007) would be more appropriate for API≤ 35.

Comparison of the Performance of Empirical Models Used for the Prediction of the PVT Properties of Crude Oils of the Niger Delta

A review of the literature has revealed the lack of a formal analysis of the performance of empirical methods for the prediction of pressure volume temperature (PVT) properties of Niger delta crude oils. This study presents an assessment of the predictive accuracy of five bubble-point pressure (P b ) correlations and five bubble-point oil formation volume factor (B ob ) correlations against a large measured PVT data bank from Niger Delta crude oils. Statistical analysis techniques were used to evaluate the performance and the accuracy of the commonly used empirical models for estimating PVT properties of Niger crude oil in order to guide designers and operators in selecting the best correlations for their particular applications. Agreement between calculated and measured P b and B ob values for the various models was very poor. The model predictions of P b and B ob can be different from the measured values by 56% and 242%, respectively. Development of improved models for predicting the PVT properties of Niger delta crude oils is urgently required.

Pressure-Volume-Temperature Correlations for Gulf of Mexico Crude Oils

Summary New empirical pressure-volume-temperature (PVT) correlations for estimating bubblepoint pressure, solution gas-oil ratio (GOR), bubblepoint oil formation volume factor (FVF), and undersaturated isothermal oil compressibility have been developed as a function of commonly available field data. Results show that these PVT properties can be predicted with average absolute errors ranging from 0.64% for bubblepoint oil FVF to 6.66% for undersaturated isothermal oil compressibility.

Correlations for predicting solution gas/oil ratio, oil formation volume factor, and undersaturated oil compressibility

Careful estimation of reservoir fluid behavior is necessary for evaluating of hydrocarbon reserves, predicting future performance, designing production facilities, and planning methods of enhanced oil recovery. Over the last decade increased attention has been focused on models for predicting reservoir fluid properties from reservoir pressure, temperature, crude oil API gravity, and gas gravity. The present study develops new empirical PVT correlations for estimating the solution gas/oil ratio, bubblepoint oil formation volume factor, and isothermal oil compressibility above bubblepoint for crude oils. Multiple regression analysis was used in developing those correlations. A total of 175 PVT analyses of crude oil samples collected from different Kuwaiti oil fields were used to develop the new correlations. Some of the recently developed correlations and those frequently used in the literature were compared to the new correlations. The correlations developed in this study exhibit significantly lower average absolute error and standard deviation than the other published correlations.

Evaluation of empirical correlations for bubblepoint oil formation volume factor

This paper evaluates several empirical correlations for estimating the bubblepoint oil formation volume factor (FVF) for worldwide application. A total of 674 experimentally obtained pressure-volume-temperature (PVT) data gathered from different published sources is used for analysis of correlated parameters of physical properties and for comparison of the accuracy of correlations. A literature survey of empirical correlations for predicting bubblepoint oil FVF is provided along with their limit of applicability. The statistical and graphical results for the data used in this study show that some of the correlations were violating the physical behavior of bubblepoint oil FVF as a function of the gas relative density. Also, all the available correlations do not adequately represent the contribution of solution gas-oil ratio and temperature at their higher values.