A Numerical Study of Flow Field and Oil Water Separation in Vertical Deadlegs

Deadleg is a kind of blind pipe connected with a main pipe used for fluid transportation, which has distinct flow characteristics. This work aims to investigate the complex flow, oil/water separation and the relation between fluid flow and water concentration of a vertical deadleg. The investigation was based on the solution of algebraic slip mixture model, which calculated the continuity and momentum equations for the mixture of oil and water, and solved the volume fraction equation for the secondary phase. The computed results indicated that the mixing zone of the deadleg consists of two circulation vortexes and the whole mixing length depends on the inlet flow intensity. Furthermore, distinct oil/water stratification forms in the stagnant zone, and the maximum water volumetric concentration is related to the length of stagnant zone and also influenced by the flow intensity of the main pipe, which could increase from 25% to 72% with inlet velocity ranges from 0.75m/s to 5m/s.