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Electric submersible pumps
Summary This paper presents electric-submersible-pump (ESP) -stage performance handling air and water in a laboratory setup. Experimental data gathered shows the effect of volumetric gas flow rate and intake-stage pressure for different rotational speeds. The presence of gas mildly deteriorates the stage performance at low volumetric gas flow rates. A sudden reduction in the stage-pressure increment is observed at this operation condition for a certain critical liquid flow rate, which marks the initiation of surging on the stage performance as mentioned by Lea and Bearden (1982). The surging initiates at lower liquid flow rates as the volumetric gas flow rate increases, which demonstrates the relationship between the surging initiation and liquid flow rate. It is also observed that the initiation of the surging moves toward lower liquid flow rates by increasing the rotational speed or the stage intake pressure. A two-phase stage-performance map was recently introduced, defining boundaries for five pump-performance regimes: homogenous, mild-performance deterioration, performance reverse slop, server performance deterioration, and nil performance (Gamboa and Prado 2011b). The current work shows that these performance regime boundaries are affected by rotational speed and intake-stage pressure.
- Europe (0.93)
- North America > United States > Oklahoma (0.29)
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (0.64)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (1.00)
- Production and Well Operations > Artificial Lift Systems > Electric submersible pumps (1.00)
Abstract The ESP system is an important artificial lift method commonly used for medium- to high-flow-rate wells for subsea developments. Multiphase flow and viscous fluids can cause severe problems in pump applications. Free gas inside an ESP causes operational problems and lead to system failures. Under two-phase flow conditions, loss of pump performance or gas lock condition can be observed. Under viscous fluids, the pump performance degrades as well. This paper provides a model on the effects of viscosity and two phase (liquid & gas) fluids on electric submersible pumps (ESPs), which are multistage centrifugal pumps for deep boreholes. The theoretical study includes a mechanistic model based on Barrios (2011) for the prediction of the degradation due to bubble accumulation. The model comprises a one-dimensional force balance to predict occurrence of the stagnant bubbles at the channel intake as a main cause of deviation from homogeneus flow model. The testing at Shell's Gasmer facility revealed that the ESP system performed as theoretical over the range of single flowrates and light viscosity oils up to Gas Volume Fractions (GVF) around 25%. ESP performance observed gas lock condition at gas fraction higher than 45%. Homogeneous Model has a fairly good agreement with pump performance up to 30% GVF. Pump flowrate can be obtained from electrical current and boost for all range of GVF and speed. Correlation depends strongly in fluid viscosity and pump configuration. The main technical contributions of this study are the determination of flow patterns under two important variables, high viscosity and two-phase flow inside the ESP to predict operational conditions that cause pump head degradation and the beginning of bubble accumulation that lead to surging Barrios (2011). For similar applications, pump performance degradation can be predicted in viscous environment and two-phase flow conditions.
- Reservoir Description and Dynamics (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring (1.00)
- Production and Well Operations > Artificial Lift Systems > Electric submersible pumps (1.00)