Integrated Analysis for PCP Systems

Abstract

One of the concerns that artificial lift engineers have to face when they are working with PCP systems is the lack of information about effective procedures for PCP diagnosis and optimization. Most of the information available is limited to explaining the importance of keeping the fluid level over the pump to avoid dry run. On the opposite side, there are some studies that explain the hydrodynamics of the pumps, and how some variables, like intake void fraction and fluid viscosity affect the pump performance. However, there is no information available that may help field engineers understand the relationship between operational conditions and internal performance of the pump to know how each condition in the well could affect the pump, and how to determine and understand which condition is best for the system. This paper introduces a new procedure to be used for understanding PCP's wells performance and therefore determine the best condition for system operation. Based on a set of simple mathematical models and patterns recognition techniques, this procedure is a useful tool to reduce the timing to analyze PCP systems and to automatically determine the best operational conditions in terms of production and performance. Introduction PCP system is a fast growing artificial lift application, during the last years many operator have been introducing this method to lift light oil and high WOR wells, thus the application window of PCP system is on expansion and the method is been used to lift lighter, gassy and low viscosity fluid a better understanding of the system performance is required. Unfortunate the information that is available to understand the downhole pumps performance is limited to some experimental studies and simplified models that don't establish a relationship between the standard system variables and pump performance. Keeping in mind that pump is the critical element of and PCP artificial lift system. This work is dedicated to explain how to predict the pump performance under a wide range of downhole condition and how to recognize the optimum operational point or downhole pump adverse condition. The set of models that are presented in this study are based on Vetter [8] and Gamboa [11] developments, whom presented simplify models to predict and analyze the hydrodynamics phenomena inside of twin screw pump and Progressive cavity pump respectively. Internal Forces in a PCP When a PCP is operated some forces are generated due to the differential pressure, the eccentricity and rotational speed, some of these forces could affect the PCP duration and installation integrity.

Economical and Performance Evaluation Between Sucker Rod Pumps and Progressive Cavity Units for Heavy Oil Production in Some Syrian Fields

“…The rotor is made of steel to resist various corrosion factors, while the stator is made in the form of a helical screw. The joint work of these two elements forms a progressive cavity pump by forming cavities between the stator and the moving part (rotor) [24] where these cavities are filled with fluid when the pump rotates and rises to the top of the well as a result of the pressure provided by the pump [23]. The pump depends in its work when transferring fluids from the bottom to the surface on achieving an ideal intersection between the rotor and the stator and avoiding the fluids slipping by maintaining the clearance between the rotor and the stator properly closed so pumps using elastomers to remain the dominant due to their economic advantage, ability to handle abrasive fluids, and low slippage [25], where cavities are formed separated from each other when rotating [26][27]…”

A 3D Transient Model for the Multiphase Flow in a Progressing-Cavity Pump

“…When gas is present in the flow stream, as the volume displaced is constant (but the density increases with pressure), the pressure distribution along the pump becomes nonlinear, and the slippage between cavities is not constant along the pump. Experimental tests showed that disproportional pressure distribution causes premature failure of pump's components, which limits the pumping of high GVFs flows (Bratu 2005). In these cases, for a constantvolume displaced pump, the liquid return is, at least, equal to the volume reduction of the gas.…”