Volatile Oil and Gas Condensate Fluid Behavior for Material Balance Calculations and Reservoir Simulation

Abstract

This work presents a comparison of different methods for generating PVT properties for modified black-oil simulation of volatile oil and gas condensate reservoir fluids. These methods are evaluated by comparing the results of the modified black-oil simulation using these methods to the results of full equation-of-state (EOS) compositional simulation. Also, the generalized material balance equation as straight line was used to calculate the initial-oil in place (IOIP). Comparisons between material balance calculations and simulation results were made. The methods are evaluated using nine actual reservoir fluid systems (six gas condensates, two volatile oils, and one wet gas) spanning a wide range of fluid properties. The obtained results indicated that modified black-oil simulation of reservoir depletion using PVT properties generated with the Whitson and Torp method provided a better agreement with full EOS compositional simulation than the other methods. In addition, the results of the IOIP calculations using PVT properties generated with the Whitson and Torp method gave better agreement with full EOS compositional simulation.

A new volatile oil-gas ratio Rv correlation for volatile oil and gas condensate reservoir fluids is developed. According to our knowledge, no correlation to calculate oil-gas ratio Rv exists in the petroleum literature. In petroleum industry, calculation of oil-gas ratio Rv has to come from combination of laboratory experiments and elaborate calculation procedures using EOS models. According to our study, Whitson and Tow method to generate Modified Black Oil (MBO) PVT properties is the most accurate method. This method will be used here to calculate Rv which used in developing the