MODELING AND SIMULATION OF A HORIZONTAL THREE-PHASE SEPARATOR: INFLUENCE OF PHYSICOCHEMICAL PROPERTIES OF OIL

Abstract

Fluids produced from oil reservoirs typically contain oil, natural gas, water, sediments, in varying amounts, and contaminating gases. Considering that economic interest usually targets mostly oil and gas, primary processing is used to separate water/oil/gas, in addition to treating these phases. Therefore, the well stream should be processed as soon as possible after reaching the surface. Separator vessels are among the main equipment used at surface production facilities, being responsible for the separation of the produced phases. This work focuses on studying the fluid dynamic behavior in a horizontal three-phase separator. To accomplish this goal, we used the computer fluid dynamics software ANSYS CFX. First, we performed a detailed analysis of a “Standard Case” to understand in detail the entire separation process within the vessel. The results show the three phases through the simulation time, analyses of the separation efficiency, different fluids flow lines, pressure gradient inside the vessel, and effect of the diverter baffle. It also considers a variation of fluid flow at the inlet of the separator. These analyses include pictures of all cases studied. Afterwards, some parameters of the standard case were altered to evaluate its influence on fluid dynamics behavior and the functioning of the separator vessel. At last, we analyzed the influences of oil density and viscosity on the separation. The oil quality affects the primary separation directly, as the oil density and viscosity increase, for example, increases the drag between the fluids and decreases the rate of sedimentation, which stickles the separation process difficult. Two out of the three cases generated satisfactory results. The simulation with the heaviest oil presented the worse results.