Experimental investigation of pressure drop in failed Electrical Submersible Pump (ESP) under liquid single-phase and gas-liquid two-phase flow

Abstract

The high viscosity of heavy oil calls for additional efforts to ensure the production in deep offshore fields, requiring innovative ways to optimize oil recovery. Considering the production by pumping system, one of the current approaches to increase the profitability is to associate the in-well Electrical Submersible Pump (ESP) and the Seabed Boosting ESP (SB-ESP). In this Tandem system, the oil must flow through the ESP while it is failed or damaged until it reaches the SB-ESP, resulting in additional head loss. This study aims to estimate the pressure drop in a damaged ESP under field conditions. For this, the study is divided into two parts. First, the pressure drop through the ESP is measured experimentally and empirical correlations are adjusted for the loss coefficient as a function of the flow parameters. Second, based on these empirical correlations and the use of black oil models for fluid properties, simulations are carried out to estimate the pressure drop under field conditions. The main contribution of this study is to provide experimental correlations for local pressure in a failed ESP since these are not available in the literature. The experimental tests used oil single-phase flow at different flow rates and viscosities. In addition, gas-liquid two-phase flow tests were performed to investigate the gas influence on the pressure drop. The experimental results indicate a decreasing dependence between loss coefficient and the Reynolds number. Regarding the fitted correlations, all equations correctly predicted the experimental data, with determination coefficients greater than 0.930. For gas-liquid two-phase flow results, the homogeneous model was suitable for predicting the pressure drop at the ESP within the experimental matrix, with gas fractions up to 35%.