A Novel Methodology to Simulate PCP Dynamics Performance Under Oil Production Conditions

Abstract

Progressing cavity pump (PCP) is a new type of hydraulic machinery applied in the petroleum industry from 1980s. To date, it has been widely used in world oil production projects. However, considering the multiple undetermined influence factors in operation, it has been always a huge challenge to create a reasonable dynamics model to simulate the dynamics performance of PCP lifting system. This challenge comes from two respects: 1) The movement of the pump and production fluid is very complex due to its special profile geometry. 2) The properties of PCP elastomers vary significantly with the nature of the production medium and environmental characteristics, resulting in a strong personalization and dispersion of PCP dynamics model. After more than ten years of research and field application, a comprehensive PCP performance simulation methodology was established, which can considerably accurately describe the dynamic characteristics of PCP under actual operating conditions. This methodology has been applied in the design, optimization and development of PCP products and has achieved good results. The numerical simulations of PCP dynamics performance are based on multi-field coupled dynamics involving different scientific fields, including solid mechanics, fluid mechanics, and material mechanics. This methodology consists of the following four parts: 1) Establishing the basic form of the three-dimensional dynamic model of stator and rotor through experimental research of the constitutive relationship of elastomer. 2) Establishing PCP flow field distribution model based on gap flow theory and experimental results. 3) Establishing stator temperature field model by analyzing the influence of ambient temperature and elastomer's viscosity property. 4) Based on the analysis results and mutual influences of the above models, establishing a systematic dynamics model and proposing the guidance for structural parameter optimization design. Simultaneously, there are three vital research conditions in this project: 1) Numerical simulating research with FEM technique. 2) Simulation test study on elastomer material properties and PCP hydraulic characteristics. 3) Field tests for PCP with different structural parameters. Experimental tests showed that, PCP dynamics performance model can be applied both in simulating the hydraulic characteristics of the existing pump and optimizing PCP design characteristics. Based on new PCP dynamics simulation methodology, optimized PCP showed significant improvements both in operating performance and running life in application in Daqing Oilfield. PCP dynamic performance simulation technology is of great significance for PCP optimization design and new product development. The improvement of this technology is very helpful for fully utilizing the advantages of PCP, thereby expanding application scale of PCP in the world. In-depth research is urgent for further understanding on PCP dynamics performance under various operating conditions.