TransAT – OLGA Coupling June 2014 S. Reboux, N. Pagan ASCOMP www.ascomp.ch reboux@ascomp.ch

1D-TransAT Coupling Motivations

Coupling paradigm: the oil & gas context Separator Oil Gas Water Horizontal-flow 1D models 3D CFD/CMFD 3D CFD/CMFD Vertical-flow 1D models Near Horizontal-flow 1D models 3D CFD/CMFD 3D CFD/CMFD 3D CFD/CMFD Wellbore Models Downhole Models  Darcy’s type of models 3D CFD/CMFD

Coupling paradigm : why and what’d be done Observation: flows in reservoir, wellbore and surface installations are tightly interrelated Solution: Coupling the various modeling approaches at different scales Result: Improved accuracy, Reduced uncertainty, Enhanced decision process

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-in Slug catchers: transient overall efficiency in response to ram-pup, pigging surge, etc… Oil 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 patterns Separators: captures efficiency and re-entrainment in response to ramp-ups, surges, etc…

1D-TransAT Coupling Model basics

Coupling strategy and validation criteria Conserved quantities: mass fluxes heat fluxes TransAT OLGA Validation criteria based on: continuity of mass fractions continuity of internal energy continuity of pressure Boundary coupling Unsteady simulations

Semi-implicit coupling method At 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 Coupling Validtion

Validation case # : single-phase flow in a pipe Purpose: Validate the pressure-flux coupling scheme for single-phase flows at steady state. Coupling boundary P0 Water Inflow TransAT OLGA Coupling boundary The 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 OLGA

Validation case # 2: slugs across a coupling boundary interface Oil Water Oil Inflow OLGA: - 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 TransAT: - 2D-axisymmetric 4m long pipe - Inlet boundary condition (oil inflow) at the bottom, coupling boundary condition at the top

Validation case # 2: slugs across a coupling boundary Comparison of the profiles obtained with OLGA (uncoupled simulation, 1D) TransAT (uncoupled simulation, 2D axisym.) OLGA-TransAT (coupled, 1D/2D axisym.) P0 P0 P0 OLGA TransAT OLGA TransAT Oil Inflow Oil Inflow Oil Inflow

Validation case # 2: slugs across a coupling boundary

Validation case # 2: slugs across a coupling boundary

Validation case # 2: slugs across a coupling boundary

Validation case # 2: slugs across a coupling boundary

Validation case # 3: Rayleigh-Taylor instability Coupling interface Oil (300K) Water (280K) Wall TransAT OLGA coupling OLGA: - 1D, 20m long pipe Closed node at top and bottom. Three different sources at the first section from bottom, for coupling TransAT: - 2D-axisymmetric 4m long pipe - Wall at the bottom, coupling boundary condition at the top

Validation case # 3: Rayleigh-Taylor instability Comparison of the profiles obtained with OLGA (uncoupled simulation, 1D) TransAT (uncoupled simulation, 2D axisym.) OLGA-TransAT (coupled, 1D/2D axisym.) OLGA OLGA TransAT TransAT

Validation case # 3: Rayleigh-Taylor instability Water flowing DOWN Oil flowing UP Water flowing DOWN Oil flowing UP

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

Validation case # 3: Rayleigh-Taylor instability

Validation case # 3: Rayleigh-Taylor instability

Validation case # 3: Rayleigh-Taylor instability

Validation case # 3: Rayleigh-Taylor instability

Validation case # 3: Rayleigh-Taylor instability The 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.

Rayleigh-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 interface

1D-TransAT Coupling Applications

1D – 3D CFD (production line – Separator) 1D pipe model (GAP) 3D CFD (TransAT)

3D CFD – 1D (capping of oil spills – ship) 1D riser model (OLGA) 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 Coupling 2D or 3D CFD (TransAT)

Zoom on coupling boundary 3D CFD – 1D (capping of oil spills – ship) Riser (Olga) t=0 t=9s Zoom on coupling boundary (TransAT) t=7s

3D CFD – 1D (water-oil mixing using jets) Mixing of water and oil in pipeline using jets of recirculated fluid

3D CFD – 1D (water-oil mixing using jets) (modelled with TransAT) Mass flow rate to CATHARE Pressure from CATHARE Tracer Injection

3D CFD – 1D (water-oil mixing using jets) (Flow field in TransAT/CATHARE)

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

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