Modified Black Oil PVT Properties Correlations for Volatile Oil and Gas Condensate Reservoirs

Abstract This work presents new Modified Black Oil (MBO) PVT properties (Rs, Rv, Bo, and Bg) correlations for volatile oil and gas condensate reservoir fluids. These new correlations do not require the use of fluid samples or EOS calculations. The correlations have the advantage of taking into consideration the effect of surface separator configuration (two and three stages) and conditions (separators pressures and temperatures). The correlations were developed using fourteen actual reservoir fluid samples (7 gas condensates, 3 near critical fluids, and 4 volatile oils) spanning a wide range of fluid behavior and characteristics. Whitson and Torp method was used to generate Modified Black Oil (MBO) PVT properties that were used as a data set for correlations development. The MBO PVT properties data points were generated by extracting the PVT properties of each sample using commercial PVT software program at twelve different separator conditions spanning a wide range of surface separator configuration and conditions to generate twelve curves for each sample. A statistical approach using a statistical software program (SPSS) was used to develop the new correlations models. The results of the new models show reasonable agreement between Modified Black Oil PVT properties generated from the new correlations and the MBO properties extracted using Whitson and Torp method. The average absolute error in the correlations was 8.5% for volatile oils and 17.5% for gas condensates. These correlations were also validated by comparing the results of modified black oil simulation using MBO PVT properties generated from these correlations to the results of full equation of state (EOS) compositional simulation. Also, the generalized material balance equation (GMBE) was used to calculate the initial oil/gas in place (IOIP/GIIP) for many simulated cases using PVT data generated from the new correlations and data generated from EOS models. The advantage of the new correlations comes from being the first in the industry (to the best of our knowledge) that explicitly take into consideration the effects of surface separators configurations (two or three stages) and conditions. Also, all input parameters in the correlations are readily available from field production data. These correlations do not require elaborate calculation procedures or PVT reports.