The objective of this five-year project (October, 1997--September, 2002) is to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project will be executed in two phases. Phase I (1997--2000) will focus on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase will include the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000--2002), the developed GLCC separator will be tested under high pressure and real crudes conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP.

This report presents a brief overview of the activities accomplished during the first quarter of the budget period. The total tasks of the budget period are given initially, followed by the technical and scientific results achieved. A brief statement on the project work planned for the next quarter concludes the report. The objective of this five-year project is to expand the research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project will be executed in two phases. Phase I will focus on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase will include the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II, the developed GLCC separator will be tested under high pressure and real crudes conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP. 3 figs.

The objective of this five-year project is to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project will be executed in two phases. Phase 1 will focus on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase will include the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase 2, the developed GLCC separator will be tested under high pressure and real crudes conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP. This report presents a brief overview of the activities and tasks accomplished during the second quarter of the budget period. The total tasks of the budget period are given initially, followed by the technical and scientific results achieved. A brief statement on the project work planned for the next quarter concludes the report.

Problems associated with the use of compact cylindrical cyclone gas/liquid (CCGL) separators can be attributed to two physical phenomena: gas carry-under and liquid carryover(LCO). Inadequate understanding of the complex multiphase hydrodynamic flowpattern inside the cylindrical separator has inhibited complete confidence in its designand use, hence the need for more research. While many works have been done with a fixed inlet slot to predict the operational efficiency of the cyclone separator, very little is known about how separator performance can be influenced due to changes in fluid properties. During the operations of the CCGLseparator the complex flow situations arising from severe foaming within the separator has not been addressed. Also the effects of emulsion formation under three phase flow conditions on the properties of cyclone separators are yet to be studied. An understanding of liquid holdup and hydrodynamic nature of flow in a compact separator under zero net liquid flow (ZNLF) and zero net gas flow (ZNGF) conditions is necessary in many field applications, especially for the prediction of LCO and in the design of the CCGL separators. Also, ZNLF holdup is an important parameter inpredicting bottom-hole pressures in pumping oil wells. This research investigated the effects of fluid properties such as density, foam and emulsion formation on ZNLF, zero net gas flow ZNGF, and LCO in compact cyclone separators; this was achieved by replacing water, which is the conventional fluid used as the liquid medium in many previous research efforts with a foamy oil while maintaining air as the gas phase. Variable-inlet-slots that regulate the artificial gravity environment created by the separator were used to check for improved separator performance. Also experiments to check separator response to a range of water-cut in three-phase flow were performed. All experiments were carried out under low constant separator pressures. The ZNLF holdup is observed to decrease as the density of the fluid medium decreases. Varying the inlet slot configurations and recombination points does not haveany effect on the ZNLF holdup when changes in density of the liquid phase occur. Comparisons with previous work show that there exists a wide variation in the LCO operational envelope when severe foaming occurs in the CCGL separator. At high water cut (greater than 30%), the separator LCO performance was observed to be normal. However, at water-cut below 30%, LCO was initiated much earlier ; this is attributed to severe foaming in the CCGL separator.

Despite the numerous advantages associated with using compact cylindrical cyclone gas/liquid separators, particularly for upstream production operations, the lack of a full understanding of the complex hydrodynamic process taking place in it and its "unfamiliarity" to oil field personnel has hindered its widespread use. The complexity associated with this technology is attributed to two limiting physical phenomena, liquid carry-over and gas carry-under. While a lot of work has been done to better understand and predict the liquid carry-over operational envelope, little or no information about methods capable of adequately predicting or characterizing the gas carry-under performance of such separators is available. Traditionally, to mitigate the gas carry-under phenomena, the use of complex control algorithms and systems has been employed. These systems make the technology expensive (as opposed to the potential cost reduction it promises) and impractical for realistic use in the oilfield where reliability is of critical importance. A simpler solution, the use of changeable or adjustable inlet-slots that regulate the artificial gravity environment created in the separator, could significantly improve the gas carry-under performance of cylindrical cyclone separators. This research has focused primarily on the use of adjustable inlet-slots. Theoretical analysis and experimental data investigating the benefits of variable inlet geometry have been provided. This work lays the foundation or validation required to perform more tests on a field-scale version to verify the results presented here. A modular design of such a variable inlet-slot inlet-section has the potential of simplifying the design and specifications of cylindrical cyclone gas/liquid separators. From the results of this investigation, it was found that the gas carry-under performance of a cylindrical cyclone gas/liquid separator could be improved considerably over a wider range of operating conditions by adjusting the size of the inlet-slots. This contradicts earlier reports of liquid carry-over improvement in separator performance. Also, for the first time, a simple method for theoretically analyzing the percent improvement in separator gas carry-under performance using the optimum g-force concept is presented. This method could be incorporated into design software for determining the slot-size configuration required for varying separator-operating conditions.