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An Introduction To PeTra Pål Hedne Statoil F&U. Background: Application. Three-phase flow simulator with tracking of individual slugs and pigs. Computation of Pressure Temperature Phase fractions Slug lengths and velocities. Background: Code History.
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Background: Application Three-phase flow simulator with tracking of individual slugs and pigs. Computation of • Pressure • Temperature • Phase fractions • Slug lengths and velocities
Background: Code History 1983 Olga IFE-SINTEF Multiphase Flow Laboratory 1985 Comp.Olga 1986 Wolga 1988 Olga w/water 1989 Olga 1.0 com. 1994 PeTra 0.1 1997 Olga97 1998 Olga2000.x com. 1999 PeTra 2.x NDP 2001 PeTra 3.x com.?
Background: Experimental Foundation Laboratory Experiments • SINTEF Large Scale Flow Loop • Small Scale High Density • Atmospheric data Field Data • Gas/condensate • Oil Field • Three Phase Flow
Three phase flow model. Separate conservation equations for: Mass • gas • oil film • water film • oil droplets • water droplets Momentum • gas+oil droplets+water droplets • oil film • water film Energy • Mixture temperature Pressure (volume) Physical Model: Conservation Equations
Water film Water droplets Gas Physical Model: Conservation Equations Oil film Oil droplets
Physical Model: Conservation Equations Moving Control Volume Va Vb Za Zb Integral form of mass equation for phase k for a moving control volume where
Physical Model: Conservation Equations Momentum equations Gas Liquid Droplets Where: l=o,w k=g,l,w and
Volume equation Combination of mass equation and equation of state Physical Model: Conservation Equations Mass flux term Compressibility
Energy equation Physical Model: Conservation Equations
Physical Model: Flow Regimes Stratified Annular when 60° Dispersed Slug
Physical Model: Closure Relationships General parameters: • Wall friction • Interfacial friction • Entrainment/deposition rates Slug parameters: • Bubble nose velocity • Gas entrained in slug body
Numerical Model: Formulation One-dimensional Upwind in space Partly implicit in time. The equations are discretized on a staggered grid: • The velocities and fluxes are defined on the section boundaries • Pressure, masses and temperature in the grid sections. Upwind values are used in the convective terms.
Numerical Model: Dynamical Grid Discretization on a moving grid for the mass equations
Implementation: Code Layout Solver engine written in C++. Graphical user interface written in G (LabVIEW). Can be linked to existing code, i.e. Fortran, C, etc. Numerical Engine netPeTra.exe Graphical User Interface PeTraGUI.exe Communicates through TCP/IP
Implementation: Classes and Inheritance General code is separated from special Reuse of code Easy to add new models
Implementation: Linked Lists Flexible, general, easy to maintain
Delivery Year 2000 • PeTra will be tested and verified against available data set. • PeTra will be delivered to the NDP partners in the form of a binary executable program for the Win32 operating system. Year 2000+ • Scandpower will provide PeTra services to the NDP companies after the completion of the NDP work in 2000 on a commercial basis. • Further development of the PeTra code after 2000 will be carried out within the SSH (Statoil-Shell-Hydro) collaboration. • PeTra will be commercialized to 3rd parties at a later stage.