Flexible Fiber-reinforced Pipe for 10,000-foot Water Depths: Performance Assessments and Future Challenges

Abstract

Abstract The primary aim of the present composite development program is to enhance access to deepwater fields in the Gulf of Mexico, Brazil, and West Africa. To accomplish that goal, composite materials are being incorporated in unbonded flexible pipelines to lower mass and enhance the overall system performance to expand the operational design envelope. In addition, the use of composite materials will allow a significant improvement in pipe operating pressure (>70 MPa), pipe operating temperature (>125C) and due to increased CO2 and H2S resistance, will improve sour service performance and lifespan. Composite materials are well known for their low density and high specific strength, stiffness and fatigue performance. These properties are desirable and will certainly enhance pipe performance, but the overall performance of the pipe during all stages of manufacture and deployment must be considered, as well as a conservative approach to introducing these new materials. Some of the key factors that need to be assessed are material failure modes under varied pipe loadings, dynamic interactions and exposure to severe oil field environments. There are several individual standards, specifications and joint industry projects (JIPs) focused on composite pipes that address some of these issues, but there is also a general lack of consensus with regard to testing standards and understanding of the long-term performance. As flexible pipe suppliers, the industry must aim to provide performance assessments and address all key challenges to allow the flexible pipe industry to build confidence in the new and enabling composite pipe technologies. In a previous paper, we presented design concepts and a toolbox approach to construct different composite pipe solutions to meet all the aforementioned performance parameters. The present paper selectively highlights important failure modes and design considerations, demonstrates an understanding of behavior in the matrix and fiber phases, and addresses concerns related to the chemical performance of composite materials. The present paper also highlights and addresses some of the concerns of composite pipes and focuses on areas for future development and testing. These results will help support the selection and standardization of analysis tools and testing methods across the industry. Bespoke testing capabilities to address the relevant failure mechanisms and installation strategies for composite pipes will also be discussed.