The paper presents a methodology of hydrocarbon fuid composition calculation on the basis of gas and condensate profiles calculated in a black oil simulator. The methodology is based on the straight dependency of the condensate-gas factor (CGR) and the reservoir pressure (Pres). In order to determine a fluid composition a dependence function between a fraction of a hydrocarbon component and CGR is created using a PVT-simulator. Having a relationship between CGR and a hydrocarbon fraction a fluid composition can be calculated using the average CGR from black oil simulation results. This methodology gives a fraction of every individual component in comparison to composition modelling, where real components should be groupped in pseudocomponents.
Proposed methodology assumes several constraints - the methodology should be applied just for gas condensate reservoirs without oil rims and the reservoir should be developed on depletion. In the work black oil and composition simulation results were compared. The paper can be useful for reservoir engineers working with gas condensates because it allows reducing simulation time without losing information about fluid composition.
Today there are two different ways of reservoir fluid description in a simulation model. They are the black oil model where properties are given for two phases - gas and liquid which are in equilibrium and the compositional model where a fluid is described by means of an equation of state.
Every of these models have advantages and constraints. The compositional model allows determination of a fluid composition. A fluid composition is important for process of construction facilities and for creation of government documentation concerning the field development planning. The black oil model allows determination of gas and condensate production but its main advantage is a relatively low time of calculation. Proposed in the paper methodology combines advantages of both ways - a relatively high calculation velocity and an ability to determine a fluid composition.
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