Composite Production Riser - Manufacturing Development and Qualification Testing
Authors: Johnson D.B. , Salama M.M. , Long J.R. , Wang S.S. 
Published: October 2008

In 1995, the U. S. Department of Commerce, National Institute of Standards and Technology (NIST), Advanced Technology Program (ATP) sponsored a project organized by several oil, service, and composite manufacturing companies to address the challenges involved in developing a viable composite production riser (CPR) suitable for deep water (3000 to 5000 feet) applications. A critical element of the project is the specification and implementation of a comprehensive testing program to validate the design and establish long term performance of a composite production riser. A testing program to verify the composite production riser design and manufacturing processes, as well as to characterize the CPR design and establish performance limits, has been developed. A total of sixty-eight full-diameter, short length CPR's will be fabricated and tested to determine cyclic and static fatigue values for comparison to the design analysis. The testing program will be designed to provide basic performance data and identify performance limitations for both the composite body and the Hydril MAC-II premium thread. The objective of the series of tests planned is to generate data from which a correlation between analytical and empirical data can be established. Testing results completed to date indicate analysis can predict single load failure scenarios and that the CPR design meets the performance criteria required. However, combined loading tests are the key to composite production riser performance and are critical in evaluating the CPR design and analysis predictions. A status report of predicted test values and results is presented in this paper.

Introduction

Composite materials offer several attractive properties such as reduced weight, improved corrosion resistance, excellent fatigue performance and, potentially, lower system cost when compared to steel by taking advantage of the ability to tailor structural properties to achieve system simplification and improved reliability. Therefore, composites have been receiving a significant amount of attention in the offshore industry as part of the effort to economically exploit deepwater oil and gas reserves. A TLP component that lends itself to taking advantage of these unique properties is the production riser. A CPR has the potential of reducing capital expenditure, due to its lighter weight and reduced requirement for pretension, and improving reliability for the development of reservoirs in deepwater using TLP's. A CPR not only reduces the required pretension, but may allow the rigid connection of the riser system to the platform, eliminating the expensive tensioners. CPR's are one of the most characterized structural composite applications for offshore platforms because they have been the subject of several major studies within the last few years. The Institut Franç du PétroIe (IFP), Aerospatiale, and several major oil companies sponsored a development and evaluation study of a 9–5/8 inch diameter CPR to prove the concept. The study was conducted between 1985 and 1990 (see Refs. I, 2, and 3). The CPR was fabricated of a hybrid of carbon and S-glass fibers. The CPR was designed to withstand a combined internal pressure of 105 MPa (15,000 psi) and axial tension of450 metric tons (1,012,500 Ibs). The CPR was also designed for a maximum external pressure (differential) of 10 MPa (1430 psi).