Deepwater Achievements and Challenges on the Extra Roncador Pipeline Installation Project
Authors: Morais Marcos , Azevedo Fabio , Kvello Odd , Tanscheit Peter 
Published: October 2008

The scope of this paper is to describe challenges and achievements related to the deepwater installation of flowlines and umbilicals for Petrobras at Campos Basin, Offshore Brazil during July-September 2000.

The project consisted of connecting three wells in the Petrobras Roncador field back to the P-36 floating production platform. Three pairs of rigid flowlines (4" and 6") were installed in water depths down to 1,870 m by the reel vessel DSND Skandi Navica. The purpose built flexible pipe installation vessel DSND Lochnagar was used to install flexible jumpers and risers to tie-in the rigid flowlines to the wellheads and platform respectively. In addition an electrohydraulic umbilical for each of the wells was installed. All subsea connections were performed by a vertical connection system, which is widely used and specified by Petrobras for Pipeline End Terminations (PLETs) and wellhead structures. Some of the flexible pipes and umbilicals used new designs of vertical connection systems.

This paper will describe the pipeline system and methods used for the installation. In addition to describing the installation vessels the text will focus on the capabilities for the laying equipment.

Furthermore, the paper will evaluate the selected design of the pipeline system, the installation method used and provide comment on alternative and improved solutions that could be considered for similar field developments in the future.

Introduction

The Roncador field was discovered in October 1996 and several technical and economical aspects for the project lead Petrobras to adopt a fast track development plan.

Phase 1 of the field development consists of 21 subsea production wells and 5 injection wells, all tied back to the P- 36 semi-submersible platform. Three of these production wells, located to the east of the platform, were to be developed early and DSND was awarded a contract to perform this scope of work. The three wells were to be connected to the P-36 floater by installation and tie-in of flexible risers, wellhead jumpers, rigid flowlines and electro-hydraulic umbilicals.

The distance from the wellheads to the P-36 floater was in the range of 10-km. The major length of the flowlines being rigid, tied-in using 120-m long flexible jumpers to the wellheads and 2,800-m flexible risers/flowlines to the platform. The water depth in the area of the installation ranges from 1,867 m at the wellhead end to 1,360-m at the platform. The project was of a fast track nature where time for the engineering and construction activities were extremely short. A letter of intent was signed late January 2000 with the installation activities scheduled to start at the end of May 2000.

Permanent project materials, with the exception of PLET's, were designed by Petrobras prior to Contract award and free issued to DSND as required. All other design and procurement activities had to be performed by DSND in the timeframe of 4-5 months. Furthermore, vessels had to be mobilised from the North Sea and a spoolbase facility also had to be constructed for fabrication of rigid pipe stalks.