Encapsulated Polymer Technology Overcomes Shear Degradation and Injectivity Loss Offshore

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 36263, “Encapsulated Polymer Technology: Overcoming Shear-Degradation and Injectivity-Loss Challenges in an Offshore Environment,” by Celia Silva, SPE, Guillaume Dupuis, SPE, and Thierry Leblanc, SNF SA. Copyright 2025 Offshore Technology Conference. _ Polymer flooding in offshore environments faces the challenge of high shear forces encountered in subsea injection systems. These extreme shear conditions can induce mechanical degradation of polymer chains. In response to this limitation, encapsulated polymer technology has been developed to mitigate shear degradation and optimize polymer performance in offshore applications. This approach involves encapsulating polymer molecules within a protective shell that shields them from degradation during injection while enabling controlled release within the reservoir. The introduction of this technology represents a significant advancement for offshore reservoir development, particularly for fields relying on subsea wells. Encapsulated Polymer Technology Encapsulated polymer-formulation technology represents a new way of considering polymer-flooding design. This approach fundamentally alters the deployment strategy for polymer flooding by decoupling the injection process from the viscosity-development process. Rather than injecting preformed polymer solutions with inherent viscosity, encapsulated systems inject low-viscosity dispersions that develop viscosity only after reaching the targeted reservoir zone. The specific implementation of the technology discussed in this paper is known as delayed viscosity polymer (DVP). DVP technology uses a core/shell structure wherein polymer chains are encapsulated within a protective shell (Fig. 1). The polymer is delivered as an inverse emulsion designed specifically for offshore operations. The encapsulation process involves preparing conventional polymers under emulsion form and then encapsulating the linear polymer chains to create the protective core/shell structure. The encapsulating shell is specifically designed to degrade under the temperature or pH conditions of the subsurface formation. The shell structure provides comprehensive protection for the water-soluble polymer against multiple degradation mechanisms. The encapsulated polymer maintains its linear structure without crosslinking, ensuring that, upon release, the polymer solution exhibits the same rheological properties as conventional partially hydrolyzed polyacrylamide systems. Controlled-Release Kinetics. The controlled-release mechanism is central to the effectiveness of encapsulated polymer technology. The release profiles are well-controlled, depending on reservoirs and flooding. Normal release times are between 12 to 72 hours following entry of the reservoir to allow the encapsulated system to be delivered to the desired interval with delayed action for displacement efficiency. The release mechanism can thus be configured to provide sustained polymer release for prolonged durations while maintaining effective concentration for the displacement process. Controlled release results in activation of the polymer in the reservoir and not in the injection equipment, increasing the effective radius in the treatment of the zone of enhanced viscosity and minimizing problems associated with injections. A section of the complete paper details technical advantages and performance characteristics of DVP technology as measured through various tests that established its extreme resistance to shear degradation, chemical stability, and injectivity preservation.