PVTsim for OLGA

PVTsim by Calsep

• Calsep – a Danish alliance partner– Founded in 1982– Specialists in PVT and fluid properties

calculations– Ensures most updated PVT calculation

methods for OLGA users

• PVTsim– On the market since 1991– Developed for process, reservoir and

laboratory engineers– More than 200 installations worldwide

PVTsim 15 main window

PVTsim OLGA Version

• Limited version of full PVTsim package– additional modules available through Calsep

• Use PVTsim to– characterize fluids

• tune characterized fluid to saturation points• mix fluids by volume, by weight or on molar basis• do flash calculations• calculate phase envelopes• calculate various fluid properties• make OLGA fluid property tables (.tab files)

Basic Models in PVTsim

• Equation of state (EOS)– Soave-Redlich-Kwong - Peneloux (SRK-P)

• default EOS– Peng-Robinson - Peneloux (PR-P)– Soave-Redlich-Kwong (SRK)– Peng-Robinson (PR)

• Water mixed with hydrate inhibitors– EOS with Huron and Vidal (1979) mixing rule

C7+ Characterization Procedure

• Pedersen et al, 1984 - estimate distributions of– mol fraction, density and molecular weight

• Based on above estimates– Calculate properties of carbon number fractions

• Tc , Pc ,acentric factor needed by EOS

– Group the carbon number fractions• TBP-fractions + estimated carbon number fractions of

plus fraction into a user defined number of pseudo components (default 12)

Estimate Molar Distribution

Estimate Density Distribution

Estimate Molecular Weight

• Molecular weight versus carbon number fraction

MWN = 14 CN - 4

– MWN : Molecular weight– CN : Carbon number fraction

Transport Properties• Viscosity

– Corresponding states principle (CSP) - default method• Pedersen et al, 1987

– Lohrenz-Bray-Clark (LBC)• same 1964

• Thermal Conductivity– Pedersen et al, 1987

Transport Properties cont.

• Surface Tension– Gas/oil: Weinaug & Katz 1943– Gas/pure water: API Technical databook, 1983– Oil/pure water: API Technical databook, 1983– Gas/salt water & oil/salt water: Firoozabadi & Ramey, 1988

OLGA Tables Content

• General specification– Pressure, temperature, total water mass fraction, gas mass fraction,

water vapor fraction of gas, • Physical properties for each phase

– density– density derivatives– enthalpy– heat capacity– entropy– viscosity– thermal conductivity– surface tension

OLGA Tables - Water Flashing

• Complete three-phase flash is always performed when water and other aqeous components(MeOH, MEG etc.) are present, i.e. full miscibility.

• For two-phase tables two liquid phases are lumped into one liquid with average fluid properties.

OLGA Tables - Water Flashing cont.

– Water properties from EOS

– Density and viscosity corrected for salts

References

• Search in pvtdoc.doc in the PVTsim directory• Characterization

– Pedersen: Ind. Chem. Process Des. Dev., 1984, 163 - 170• Mixing rule

– Huron, M. J. and Vidal, J.: Fluid Phase Eq. 3, 1979, 255.• Transport properties

– Weinaug, C. F. and Katz, D. L., Ind. Eng. Chem. 35, 1943, 239.– Lohrenz, J.,, Bray, B. G. and Clark, C. R.

J. Pet. Technol., Oct. 1964, 1171-1176.– Pedersen et al: Chem. Eng. Sci. 42, 1987, 182-186– Pedersen et al: J. Can. Pet. Tech, 1988– Firoozabadi, A. and Ramey, H. J., Journal of Canadian Petroleum

Technology 27, 1988, pp. 41-48.

PVTsim - Composition Input

PVTsim - Characterized Fluid

PVTsim - Mixing Fluids

PVTsim - Recombining Fluids

PVTsim - Phase Envelope

0

1000

2000

3000

4000

5000

6000

-100 0 100 200 300 400 500 600 700 800 900

Temperature/°F

Crit P

TEST 4 BHS OIL C10+

PVTsim - OLGA fluid table file input

Specify a sufficiently wide region of P and T.Account for occasional peak (high and low) values.

e.g.Tmin could be ≤ -10 CPmin should be ≥ 0.5 Bara

Example

Extract of fluid table

Fluid tables - Check the Results!

• Check the fluid tables for discontinuities and strange tendencies as function of P and T e.g.– Gas mass fraction– Densities– Derivatives of hydrocarbon liquid density

• Check the single phase regions in particular (gas mass fraction equals 0 or 1)

• Use the plotting facility in the OLGA 5 GUI

OLGA 5 fluid plotting (open a .tab file)

Densities as function of P at 200 Bara