Challenges During Surface-Facility-Project Implementation for a Full-Field Polymer Flood

Abstract

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 181615, “Challenges During Execution, Construction, and Operational-Readiness Phase of Surface Facilities in a Full-Field Polymer-Flood Project,” by Santosh Mohanram, Premashis Bhaumik, SPE, and Shagun Jain, SPE, Cairn India, prepared for the 2016 SPE Annual Technical Conference and Exhibition, Dubai, 26–28 September. The paper has not been peer reviewed. This paper presents key challenges in surface-facilities project implementation during the construction and operational-readiness phase of a project and presents results from full-field implementation. The key areas discussed are operational difference in the available technologies for concentrated-polymer dissolution, transfer of viscous polymer mother solution with minimal viscosity loss, efficacy of the pumping facility with high-viscosity non-Newtonian liquid, and supply-chain strategy. Introduction Because of positive responses from an enhanced-oil-recovery pilot, a full-field polymer-flood development plan was implemented in the Mangala field in India. Selecting the right facility design was of paramount importance once the pilot study confirmed the benefits of polymer flood over waterflood. A multilayered pattern drive with 129 injectors in an intense brownfield execution poses immense challenges for facility engineering. Thus, the world’s largest polymer- injection plant was built, primarily by scaling up the pilot. New Facility The current facility setup consists of remote well pads with both producing and injection wells connected with the production-fluid and injection-water network. A central polymer-preparation facility was constructed to prepare the concentrated polymer solution, called the mother solution, at various levels of concentration. The concentrated polymer solution is transferred from the central polymer facility to the well pads through pipeline distribution. Once at the well pads, the concentrated polymer solution is diluted with injection water at a specific ratio and injected into the individual wells. Key Challenges Technologies for Concentrated-Polymer Dissolution. The industry has only two standard technologies for dissolving polymer into water—the eductor-type units and slicing/mixing units. Conventional eductors work on the Venturi principle and allow for the mixing of the polymer powder and water up to certain concentrations. Slicing units, on the other hand, reduce the polymer particle size with a cutting head, reducing the polymer particle to a uniform size and allowing for significantly higher polymer concentrations without affecting the polymer molecular weight. In recent years, the slicing-unit design has become more compact and capable of producing highly concentrated polymer mother solution with less sensitivity to flow variation.