Artificial Lift Selection and Testing for an Enhanced Oil Recovery Redevelopment Project-Lessons Learned: From Laboratory Results and Pump Test Facility Experiments to Field Pilots

摘要

OMV Austria E&P GmbH is currently focusing on a significant chemical enhanced oil recovery (EOR) redevelopment project for a mature oil field. Cost-effective and flexible artificial lift systems (ALS) for the production wells are seen to be crucial for the economic success of this project. This paper shows the artificial lift selection process and results for the enhanced oil recovery redevelopment project, based on laboratory results, pump test facility experiments, and field pilots. The selected ALS for the chemical EOR field must be capable of dealing with changed fluid properties due to back produced polymer-water-oil mixture and achieve the target production rates at a reasonable pump run life. Field experience and an extensive testing program provided the information and data for the design of the ALS. Potential ALS types were screened according to their rate capabilities and flexibility, OMV Austria’s in-house experience, necessary surface networks, and design constraints. A literature review showed that there is only limited information available about the required adaptations and mitigation measures for the pump designs for polymer back producing wells. The consecutive risk assessment resulted in the necessity of testing the pump performance in the in-house laboratory, OMV Austria’s fields, and the pump test facility at the Montanuniversitaet, Leoben. The effects of chemical and rheological behavior of the polymer solution on the production system were analyzed and demonstrated the complexity of handling non-Newtonian fluids. The detailed analysis of the gathered information resulted in the decision to select electrical submersible pumps (ESPs) and sucker rod pumps (SRPs) as the artificial lift methods for the field redevelopment. The ESP lab test results provided a clear indication for severe derating of the pump performance when pumping polymer fluid, which can reach more than 50%, depending on the polymer concentration. The performed polymer ESP pilot well tests provided the most realistic conditions and confirmed the lab test results. The SRP lab tests have indicated an increase of the viscous friction between 20% to 50%, depending of the strokes per minute. This paper describes the selection process of ALS for the producing wells in a chemical EOR field, based on testing results and field pilot experience of ESPs and SRPs within OMV Austria. The required design adaptations due to the chemical and rheological behavior of the back produced polymer are identified, implemented, and installed in the field.