Development of Drillpipe-Riser-Intervention Systems Offshore West Africa

Fig. 1—Sample preparation for temperature-cycling test.

This paper details the technical and economic challenges in west Africa that have led to the design of drillpipe-riser-intervention-system (DPRIS) solutions. Depending upon the field requirements, two different types of drillpipe-riser systems using a proprietary double-shoulder connection have been used by operators. A first solution was developed in 1999 featuring a seal ring close to the external shoulder. Subsequently, a new solution featuring a gas-tight metal-to-metal seal on the pin nose was developed.

Introduction

Well-completion and -intervention operations in offshore environments are growing in complexity because of increasing water depths and working-­pressure requirements. These environmental factors are having a major effect on tube-body minimum-tensile-load capacity and gas-tight-connection requirements. As early as 1996, an operator accelerated the development of a new type of completion and intervention system when it discovered the Roncador field in 1800 m of water offshore Brazil. A dedicated project team was created to develop the DPRIS. The operator had already identified its need for a mobile early-production riser for use with a floating production unit performing extended flow testing of production wells. The new DPRIS could be used for subsea tubing-hanger and production-tree installations and as an early-production riser.

DPRIS use has greatly expanded; more than 50 systems currently operate in deepwater offshore regions. The first use of the system in west Africa occurred in 1999 on the Girassol project. A second-generation drillpipe riser has since been designed featuring new connection designs and  hydrogen-sulfide-resistant materials and has been subject to evaluation, testing, and field performance.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 170308, “Drillpipe-Riser-Intervention-System Successful Experience in Offshore West Africa,” by Henri de Fonvielle and Laurent Bordet, Vallourec Drilling Products; William Campbell and Nenad Susak, Total; and Mitra Marajh,FMC Kongsberg International, prepared for the 2014 SPE Deepwater Drilling and Completions Conference, Galveston, Texas, USA, 10–11 September. The paper has not been peer reviewed.
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Development of Drillpipe-Riser-Intervention Systems Offshore West Africa

01 June 2015

Volume: 67 | Issue: 6

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