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Fluid Preprocessor

Handling of fluid compositions and PVT data is a key element in PVTsim. Compositional analyses from a standard PVT report are easily entered into and stored in PVTsim. When opening the composition input menu, a default list of components is shown. Additional components may be retrieved from PVTsim's comprehensive component database, or the default list of components may be changed to comply with the user's individual needs.

PVTsim distinguishes between the following types of components

A composition to at least C7+ is required for a plus fraction type of composition. Molecular weights and densities are needed for each C7+ carbon number fraction. The user may rely on default values, or enter molecular weights and densities from a PVT report.

By default PVTsim handles components up to C80, but components up to C200 can be handled by use of an optional heavy oil characterization procedure.

By characterizing a plus fraction type of fluid, all component properties needed in subsequent simulations are established. The plus fraction is extrapolated to max. C200 and the C7+ components are grouped into pseudo-components.

User defined lumping is an option. A defined component may be grouped with any other defined component. The C7+ carbon number fractions may be lumped into a user specified number of components, and the user may as an option specify carbon number cut points. Previously characterized fluids may also be entered. A "Complete" button enables missing properties to be estimated.

Multiple compositions may be characterized to the same pseudo-components, mixed or weaved. A gas and an oil composition may be recombined according to a given separator GOR. Lumped compositions may be delumped to full component number again.

New components can be added to the database. Compositions may be entered in either mole% or weight%.

PVTsim may be used with the SRK or the PR equation of state (76 or 78 modifications) with or without volume translation. Temperature dependent volume translation parameters are an option.

Characterization can be set to match saturation point.

Bottom hole samples are often contaminated by base oil from drilling mud. Numerical rinsing of contaminated fluid compositions may be accomplished by use of a "clean for mud" option.

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