Investigation Of Oil-Water Separation Technology And Stratified Transportation

It is a strong desire to develop a high-efficiency oil-water separationtechnology for the offshore oil-gas exploitation and transportation. To designa compact, high-efficiency compound oil-water separator is a main goal of theresearch in this field. The helically coiled tube separator is one of theseefficient equipments. The investigation of the separation of oil-watertwo-phase flow in a helically coiled tube is important for the designing.Therefore, in this paper, the software, FLUENT, is applied for numericalsimulation, in which the Euler-Euler method and Euler model are adopted.The experimental condition with holes on the out side of the helical tube isconsidered in the simulation. The characteristics of the flow and themechanism of separation are studied and the numerical results agree well withthe experimental data. Some suggestions for improving experimental researchare made.Stratified flow is considered a basic flow in two-phase system. Themixed transferring of stratified flows is an important technology in petroleumengineering. Research in two-phase stratified flow, which aims to know thecharacteristics of the flow integrally and the relationship between the volumeflow ratio, the hold-up and the pressure drop, normally focuses on the shearstress between the wall and the phases or between the phases. Generally, theinterface between two phases is plane, except in some special conditions, suchas in reduced gravity systems, capillary systems, in the case of low densitydifferential or small ID pipe flows. In these cases, the surface forces becomeimportant compared with the gravity and thus the interface between twophases is curved. We did some numerical experiments by the VOF method inFLUENT and the Level-Set method. Both the advantage and the disadvantageof these two methods are given in the paper. A corrected exact analyticalsolution for the interface shape of two-phase stratified flow, which considersthe effects of the surface tension of the two fluids and the contact angle, isgiven. The analytical solution has been used to improve the Two-Fluid Model(TFM).TFM is a model for two-phase stratified flow. It can describe theattribute of the flow. We improve the old TFM by redefining the frictionfactors, characteristic velocities, hydraulic radius. The Advanced Two-FluidModel (ATFM) is developed to fit the liquid-liquid two-phase stratified flowwith the curved interface and the results fit well with the experiment results ofthe oil-water stratified flow in small ID tubes. The ATFM can not only predictthe position of three-phase point and the pressure drop, but also obtain thetransition range for the characteristic velocities of the two phases. It is ofpractical value for the oil-water mixed transferring.