Qualification of Enhanced SCR Design Solutions for Improving Fatigue Life at Touch Down Zone

摘要

Steel Catenary Riser (SCR) is a proven and economic riser system solution, as a tie-back production riser and as an export riser from floating production systems, in development of oil and gas fields in deepwater and ultra-deepwater. But application of SCRs is challenged in some cases due to high fatigue damage at Touch Down Zone (TDZ) from a combination of field specific parameters, such as riser size, fluid characteristics, vessel motions, metocean parameters, soil conditions, and water depth. A number of solutions to this problem were evaluated in a JIP during 2004 and four selected solutions were carried forward to qualification testing and analysis during 2005 and 2006. The JIP is being supported by 10 companies, including 5 major manufacturers whose products are used in these solutions. The solutions for fatigue life enhancement at SCR TDZ include use of: light weight coating over steel riser sections; steel riser sections with upset ends; high strength steel riser sections with integral connectors; and titanium riser sections. The mechanisms through which fatigue life enhancement is achieved vary for these solutions. Two case studies were undertaken in this JIP to define the requirements for each of these solutions with potential to increase the fatigue life at SCR TDZ by a factor of 10 or more. The design, analysis, manufacturing of samples, laboratory and full scale testing efforts undertaken to qualify these solutions for intended applications and current status of the JIP are identified. With the qualification effort undertaken in this JIP, the project readiness of these solutions has been increased for their consideration in SCR designs with TDZ enhancement at the concept selection and front end engineering stages of deepwater field development projects. The potential alternative applications of the solutions developed in this JIP are also identified.