Experimental and numerical study of two-phase pressure drop in downhole shut-in valve with Unified Comprehensive Model formulation

• We model two-phase flow of water–air and oil–air in a downhole shut-in valve.
• Using Unified Comprehensive Model (UCM) formulation for two-phase pressure drop.
• Simulated pressure drops are compared to experimental values and other methods.
• 1D mathematical formulation with least squares spectral elements.
• UCM friction model provides best comparison with experimental pressure drop values.

The Unified Comprehensive Model (UCM) formulation for two-phase flow identifies first the flow pattern, and applies subsequently the appropriate pressure drop calculation. In this work the UCM has been extended for dealing with the complex two phase flow in a shut-in valve. In particular, local two phase pressure drops were included where the loss coefficients were obtained from full 3D CFD simulations. The final mathematical model was solved by a least squares spectral element method. Two-phase flow simulations with the extended UCM were validated with experiments performed on a full scale mock-up of the valve. The suggested models provide a good estimation of the pressure drop. The predicted flow patterns from the UCM are also confirmed by the experiments.