Artificial Lift Selection and Testing for an EOR Redevelopment Project – Lessons Learned from Field Pilots, Laboratory and Pump Test Facilities

Abstract

Abstract OMV Austria E&P GmbH is currently focusing on a major chemical enhanced oil recovery redevelopment project for a mature oil field within the Vienna Basin. Cost-effective and flexible artificial lift systems (ALS) for new and existing production wells within the planned polymer patterns are seen to be crucial for the economic success of this project. The selected ALS must be capable of dealing with changed fluid properties due to back produced polymer and achieve the target production rates with a reasonable run life. Prior to final selection and following field rollout, the production capabilities of the selected ALS must be demonstrated. Field experience and an extensive testing program supplied most essential information and data for the necessary design adaptations for future polymer back producing wells. The ALS were screened according to their rate capabilities and flexibility, OMV Austria's in-house experience, necessary surface networks and design constraints. Uncertainties regarding reservoir and production system behaviors in a future enhanced oil recovery (EOR) full-field application were identified. 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 demonstrated the necessity of testing the pump performance in the in-house laboratory, OMV Austria's fields, and pump test facilities sponsored by OMV. Existing polymer pilot patterns are used to derive information and lessons learned, which are continuously implemented in the artificial lift basis of design for the field rollout. The effects of chemical and rheological behavior of the polymer solution on the production system were analyzed and clearly demonstrated the complexity of handling non-Newtonian fluids. The combination of all requirements described above resulted in the decision to select electrical submersible pumps (ESPs) and sucker rod pumps (SRPs) as the desired artificial lift methods. The ESP test facility gives clear indications for severe derating of the pump performance when pumping polymer. The polymer ESP pilot wells are providing the most realistic input data, feeding into the final pump and motor design. The influence of polymer concentration on SRPs was shown with polymer spiking tests and a SRP test facility. From field experience several conclusions on the properties of the back produced polymer could be derived. Especially the degree of mechanical degradation of the polymer solution is essential for the artificial lift designs. Also, challenges regarding aspects of flow assurance were experienced; their reasons and potential remedies are currently analyzed in the laboratory. This paper describes the selection, testing program and pilot experience of ESPs and SRPs under the most realistic conditions within OMV Austria. The necessary design adaptations due to the chemical and rheological behavior of the back produced polymer are identified. The sum of all test activities should prepare OMV Austria for one of the largest field redevelopment projects in its history.