Sahand Pirouzpanah

Evaluation of a Close Coupled Slotted Orifice, Electric Impedance, and Swirl Flow Meters for Multiphase Flow

The feasibility of a multiphase flow meter utilizing closely coupled slotted orifice and swirl flow meters along with an impedance sensor is investigated. The slotted flow meter has been shown to exhibit well behaved response curves to two phase flow mixtures with the pressure difference monotonically increasing with mixture density and flow rate. It has been determined to have less than 1% uncertainty in determining the flow rate if the density of the fluid is known. Flow visualizations have shown that the slotted orifice is a very good mixing device as well producing a homogenous mixture for several pipe diameters downstream of the plate. This characteristic is utilized to provide a homogeneous mixture at the inlet to the swirl meter. This is possible since the slotted orifice is relatively insensitive to upstream and downstream flow disturbances. The swirl meter has been shown to indicate decreased flow rate as the mixture density increases which is opposite to the slotted orifice making the solution of the two meter outputs to obtain density and flow rate feasible. Additional instrumentation is included. Between the slotted orifice and swirl meter where the flow is homogenous a custom manufactured electrical impedance sensor is installed and monitored. This array of instrumentation will provide three independent measurements which are evaluated to determine which system of equations are robust enough to provide accurate density and flow rate measurement over a wide range of gas volume fractions using a very compact system.Copyright

Flow Characterization in an ESP Pump Using Conductivity Measurements

Electrical Submersible Pumps (ESPs) are used in upstream petroleum industry for pumping liquid-gas mixtures. The presence of gas in the flow reduces the efficiency of ESPs. To investigate the effect of gas in the flow medium, Electrical Resistance Tomography (ERT) is performed on the two diffuser stages in a three-stage ESP which was manufactured by Baker Hughes Company. In an ERT system, the relative conductivity of the two-phase fluid mixture in comparison with the conductivity of pure liquid is measured which is used to obtain the Gas Volume Fraction (GVF) and mixture concentration. The measured GVF and concentration is used to characterize the flow for different flow rates of water and air, inlet pressures and rotating speeds.Copyright

Temporal Gas Volume Fraction and Bubble Velocity Measurement Using an Impedance Needle Probe

Impedance probes are used by the oil and gas industry to investigate multiphase flow behavior. In this study, an impedance needle probe has been developed to measure the local and temporal gas volume fraction in conductive and non-conductive process fluid. Measuring both resistance and capacitance enables this probe to be functional in both types of fluids and facilitates the measurement of local bubble velocity. Two 1/32″ insulated brass (alloy 260) rods with bare tips protrude into the flow. The gap between the electrodes is designed to be 0.085″. The probe can measure directional bubble velocity by measuring duration of signal gradient from liquid to gas transition. For a known distance between electrodes and by the measured time, directional bubble velocity in the direction of the connecting line between electrodes can be measured. The ratio between the time interval when signal is non-zero to the total time represents the temporal gas volume fraction.Copyright

CFD-Based Design Improvement for Single-Phase and Two-Phase Flows Inside an Electrical Submersible Pump

Computational fluid dynamics (CFD) is widely used to simulate fluid flows in turbomachinery. A detailed CFD study was performed to enhance the design of an electrical submersible pump (ESP) manufactured by Baker Hughes. The pump has a special patented impeller design enabling it to handle up to 70% gas volume fraction (GVF).A CFD-based design study was performed on the ESP diffuser (for the first time) to improve the pump’s performance and reduce losses. The CFD model was initially validated using experimental results. Different designs were simulated to reach the optimum design. Many factors affect pump performance, including flow separation losses in the stator (such as the number of blades, the meridional profile of the pump and the shape of the stator blades). In addition, a non-uniform flow while exiting one stage affects the rotor performance of the next stage. Therefore, improving the diffuser design improves the current stage performance as well as the performance of the next rotor. In this study, improved designs show that optimizing the stator design can increase the static pressure of the pump by 4% for single-phase flow, and 23% for two-phase flow in the simulated cases.Copyright

Predictive Erosion Modeling in an ESP Pump

Electrical Submersible Pumps (ESPs) are widely used in upstream oil production. The presence of a low concentration solid phase, particle-laden flow, in the production fluid may cause severe damage in the internal sections of the pump which reduces its operating lifetime. To better understand the ESP pump’s endurance, an ESP-WJE1000, manufactured by Baker Hughes Company was studied numerically to determine the pump’s flow behavior at its best efficiency point. Computational Fluid Dynamics (CFD) analysis was conducted on two stages of the pump’s primary flow path employing Eulerian-Granular scheme in ANSYS-Fluent. The key parameters affecting the erosion phenomena within the pump such as turbulence kinetic energy, local sand concentration and near wall relative sand velocity were identified. The predictive erosion model applicable to pumps was developed by correlating the erosion key parameters with available experimental results.Copyright