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TransAT OLGA CouplingJune 2014S. Reboux, N. Pagan ASCOMPwww.ascomp.chreboux@ascomp.ch11D-TransAT CouplingMotivationsCoupling paradigm: the oil & gas context

SeparatorOilGasWaterWellbore ModelsNear Horizontal-flow 1D modelsVertical-flow 1D models Darcys type of modelsHorizontal-flow 1D modelsDownhole Models3D CFD/CMFD3D CFD/CMFD3D CFD/CMFD3D CFD/CMFD3D CFD/CMFD3D CFD/CMFDCoupling paradigm : why and whatd be done

Potential examples of 1D/TransAT coupling Manifold splits, tee splits, elbows or bends: Transient redistribution of oil, gas or water phases before flow into downstream pipes. Subsea tree or jumper: cool-down after well shut-inSlug catchers: transient overall efficiency in response to ram-pup, pigging surge, etcOil spills: design optimization of subsea containment designs that are connected to a riser.Piping inserts / inline equipment: investigate discontinuities between up and downstream multiphase slip flow patternsSeparators: captures efficiency and re-entrainment in response to ramp-ups, surges, etc1D-TransAT CouplingModel basicsCoupling strategy and validation criteriaTransATOLGAConserved quantities:

mass fluxesheat fluxesValidation criteria based on:

continuity of mass fractionscontinuity of internal energycontinuity of pressure

Boundary couplingUnsteady simulations7Semi-implicit coupling methodAt each time step:

TransAT receives pressure data from OLGA, together with the sensitivity of the pressure to different mass fluxes. They define a local linear constraint.

TransAT determines pressure and mass fluxes by iteratively solving the implicit equation:

1D-TransAT CouplingValidtion Validation case # : single-phase flow in a pipeCoupling boundaryTransATOLGACouplingboundaryP0Water InflowThe pressure profile do not match exactly because the pressure drops are slightly different in TransAT and in OLGA.

This is because the inflow profile set in TransAT does not match (in this case) the one specified in OLGAPurpose:Validate the pressure-flux coupling scheme for single-phase flows at steady state.

10P0CouplinginterfaceOilWaterOil InflowTransAT:

- 2D-axisymmetric 4m long pipe- Inlet boundary condition (oil inflow) at the bottom, coupling boundary condition at the topOLGA:

- 1D, 20m long pipe

Pressure outlet condition at the top, closed node at the bottom.Three different sources at the first section from bottom, for coupling

Validation case # 2: slugs across a coupling boundary11Comparison of the profiles obtained with

OLGA (uncoupled simulation, 1D)TransAT (uncoupled simulation, 2D axisym.)OLGA-TransAT (coupled, 1D/2D axisym.)P0Oil InflowP0Oil InflowP0Oil InflowOLGATransATOLGATransATValidation case # 2: slugs across a coupling boundary12

Validation case # 2: slugs across a coupling boundary13

Validation case # 2: slugs across a coupling boundary14

Validation case # 2: slugs across a coupling boundary15

Validation case # 2: slugs across a coupling boundary

16TransAT:

- 2D-axisymmetric 4m long pipe- Wall at the bottom, coupling boundary condition at the topOLGA:- 1D, 20m long pipe

Closed node at top and bottom.Three different sources at the first section from bottom, for couplingCouplinginterfaceOil (300K)Water (280K)WallValidation case # 3: Rayleigh-Taylor instability

TransATOLGAcoupling17Comparison of the profiles obtained with

OLGA (uncoupled simulation, 1D)TransAT (uncoupled simulation, 2D axisym.)OLGA-TransAT (coupled, 1D/2D axisym.)OLGATransATOLGATransATValidation case # 3: Rayleigh-Taylor instability18Oil flowing UPWater flowing DOWNWater flowing DOWNOil flowing UPValidation case # 3: Rayleigh-Taylor instability19

U > 0U > 0U > 0U < 0U < 0

U > 0U > 0U > 0U < 0U < 0

U > 0U > 0U > 0U < 0U < 0

U > 0U > 0U > 0U < 0U < 0

U > 0U > 0U > 0U < 0U < 0t=8st=5st=10st=9st=7sValidation case # 3: Rayleigh-Taylor instability

Validation case # 3: Rayleigh-Taylor instability21

Validation case # 3: Rayleigh-Taylor instability22

Validation case # 3: Rayleigh-Taylor instability23

Validation case # 3: Rayleigh-Taylor instability24The results obtained using OLGA or TransAT (alone) are not consistent for this test case.The oil velocity is under-predicted by OLGA (perhaps because it is using friction models based on flow regimes from fully developed flows)The evolution in time of heat fluxes, mass fractions and pressure variations given by OLGA cannot be trusted quantitatively under these conditions.The coupled simulations suffer from this lack of consistency between the models of the two codes, but they are nonetheless stable, give plausible results and satisfy the conservation laws.Validation case # 3: Rayleigh-Taylor instability25Rayleigh-Taylor instability: results

Pressure at the coupling interface

Mass fluxes at the coupling interface

Mass fraction at the coupling interface

Heat flux at the coupling interface

Temperature at the coupling interface261D-TransAT CouplingApplications

1D 3D CFD (production line Separator)

3D CFD(TransAT)1D pipe model(GAP)

2D or 3D CFD(TransAT)1D riser model(OLGA)Coupling3D CFD 1D (capping of oil spills ship)Purpose:Proof of concept for complex multiphase flow with 3D/1D coupling.Demonstrate the robustness and physical consistency of the coupling method for subsea applications

t=0t=7st=9s3D CFD 1D (capping of oil spills ship)

Riser(Olga)Zoom on coupling boundary(TransAT)30Mixing of water and oil in pipeline using jets of recirculated fluid

3D CFD 1D (water-oil mixing using jets)

Mass flow rate to CATHARE Pressure from CATHARETracerInjection

(modelled with TransAT)3D CFD 1D (water-oil mixing using jets)

(Flow field in TransAT/CATHARE)

3D CFD 1D (water-oil mixing using jets)

3D CFD 1D (Cross heating of oil wells)

3D CFD 1D (Cross heating of oil wells)