Prospects of Riserless Mud Recovery (RMR) Technology for Offshore Carbon Sequestration (OCS)

Abstract

With the steady progress of the global energy transition and the pursuit of “dual carbon” goals, Offshore Carbon Sequestration (OCS) has emerged as a pivotal strategic pathway within Carbon Capture and Storage (CCS) initiatives aimed at mitigating climate warming. Nevertheless, the drilling of OCS injection wells faces severe challenges, including narrow geological pressure windows, high risks of shallow geohazards, stringent environmental protection standards, and prohibitive construction costs. Riserless Mud Recovery (RMR) technology, as a novel and eco-friendly deepwater drilling technique, provides innovative technical support for OCS by establishing a closed-loop seafloor circulation system that achieves dual-gradient pressure control and “near-zero discharge” of drilling fluids. This paper systematically reviews the development history and technical principles of RMR. By integrating the specific requirements of OCS injection well drilling—such as wellbore integrity, environmental protection, and shallow hazard mitigation—the study provides an in-depth analysis of the application potential of RMR in drilling CO2 injection wells within shallow formations. Furthermore, it demonstrates the engineering feasibility of RMR across technical, environmental, and economic dimensions. Building on this analysis, the paper discusses current technical challenges regarding key equipment research and development, adaptability to complex operating conditions, enhancement of intelligent control systems, and the establishment of technical standards. It also outlines the prospects for the integrated development of RMR with emerging fields, including hydrate-based carbon sequestration, intelligent drilling and completion, and carbon sequestration in far-reaching deep-sea areas. The research indicates that RMR technology can effectively resolve the dual constraints of cost control and environmental protection in OCS drilling. With breakthroughs in critical hardware, such as high-displacement subsea lift pumps, and the deepening of cross-disciplinary integration, RMR is poised to become an essential technical pillar in the field of offshore carbon sequestration.

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