Diverless Support Systems for an Improved Rigid/Flexible Risers Competitivity on Pre-Salt Fields

Abstract

Riser pull-in is a time-consuming activity. It is required to start the Floating Unit Production (FPU) and its ramp-up. In additional, conventional systems are dedicated to install rigid riser or flexible riser in the Floating Production Storage and Offloading (FPSO). This article presents the challenges overcome and ongoing on developing the riser & hull interface system for the pre-salt fields to speed up the riser connection and to provide flexibility for the riser technology a posteriori of the design system. This work details the functionality, design, manufacturing, and pull-in activities of two different systems developed for pre-salt fields: (i) the Diverless Bellmouth with hydraulic actuators (BSDL-SI), intended for flexible riser or umbilical; (ii) and the Unified Diverless Support Tube (TSUDL), a device with the capability to support either flexible or rigid risers, with reduced dependance on shallow diving operations, allowing a broader competitivity on the riser technology solution and therefore more possibilities for the subsea layout design. Improving a diver-assisted equipment to a diverless design significantly increases its complexity by means of enhanced mechanisms, hydraulic actuation, and monitoring systems. The authors present, for both systems BSDL-SI and TSUDL, the challenges overcome for the different project phases: design, manufacturing, and pull-in activities. It is presented pull-in activities comparison between the developed and standard support riser & hull interface systems to illustrate the efficiency improvement in the operations with using of those new technologies. They enable to anticipate the production and to reduce the overall project cost and greenhouses gases emissions. Moreover, the diving assisted activity is one of the riskiest to the professional in the oil and gas industry. Therefore, by eliminating these activities it will make the project of oil and gas industry safer. These new concepts of diverless riser supports are disruptive on the offshore industry, as they consider control & monitoring by the FPU, although using field proven components. Considering this strategy, a new approach to the market is being used to reduce the implementation and schedule risks, such as an early engagement during the design phase with the suppliers, leading to a new concept of technology licensing and pre-qualification that will be presented on this paper.