Polymer Flooding: Surface Facility Design for Mitigating Induced Vibrations and On-field Performance Validation

Abstract

This paper is in continuation to SPE-187306- MS "Enhanced Oil Recovery - Polymer Flooding: Surface Transfer Facility Design, Graphical Approach for Hydraulics and Tackle Induced Vibrations," with core focus on induced vibrations in surface facilities and corresponding mitigating steps. Cairn Oil & Gas, vertical of Vedanta Limited, has implemented one of the largest Enhanced Oil Recovery Process (Polymer flood) for its Mangala field (in Rajasthan block). The current facility set up follows centralized polymer handling facility concept. This concept was found to be the most economic and it ensured an optimal utilization of the existing water flood network. Large volume of polymer injection requirement for Mangala polymer project drove the requirement of higher concentrated mother solution to reduce the Central Polymer Facility (CPF) plant size. The CPF is among one of the largest centralized polymer solution preparation facilities in the world, producing 80,000 barrels of polymer mother solution at 15,000 ppm concentration. The concentrated polymer solution (mother solution) is transferred from the CPF to the various existing well-pads (15 nos.) via a pipeline distribution. The mother solution transfer pipeline network is of over 15 km. Once at the well pads the concentrated polymer solution (mother solution) is diluted with the injection water at a specific dilution ratio. The diluted solution is then injected into the individual wells through the existing injection water lines after boosting the pressure. However, post Mangala EOR commissioning some piping system failures have been experienced in polymer solution facility. These failures are largely attributed to vibration induced fatigue and arose both, at the suction and discharge lines of the Positive Displacement polymer Injection Pumps. The vibration is attributed mainly to the visco-elastic nature of the polymer fluid. The paper covers the issue through following steps: Evaluating the vibration effect on surface facilities and equipment due to polymer fluid rheology Identifying, in detail, the sections of surface facility susceptible to equipment failure and performance loss. Presenting lessons learnt based on field experience Qualifying effective design solutions to address the issues of flow induced vibration Establishing the efficacy of the recommendations through performance evaluation post on-site design modification