The Scarab / Saffron Fields Development, Subsea System
Authors: Ellaithy Wael F. , Davis Hugh , Gaber Mohamed , Helal Mostafa F. 
Published: October 2008

The Scarab/Saffron fields are located 90km from shore in up to 650m of water. The selected development concept is a long distance subsea tieback of the wells direct to the shore with control by umbilicals. Scarab / Saffron is the world's second longest tieback lines. This paper describes the technical challenges of designing a subsea system that can manage the multiphase flow, distribute chemicals to the wells and control production and yet which must be installed and maintained at beyond diver depths. The paper concludes with the lessons leant and the area for improvement in similar tieback. Some of the lessons leant required immediate modification to the system, others yet to be captured in similar installations.

One of the keys to a successful subsea development is system engineering. This discipline is important to all projects but is critical to deepwater subsea projects. Once installed, there is limited capability to intervene on the system or to add additional functions unless this has specifically allowed for in the systems or equipment design. The paper will describe in outline the efforts that have been made in the areas of Field Layout, Flow Assurance, Control Philosophy and Umbilical Design.

Once sufficient system engineering is complete and the functional requirements of the subsea system have been determined, equipment design can begin, and the most important contributions come from Installation and Intervention engineers. The equipment must perform the functional requirements of the system design, but it also has to be installed and allow future intervention without the aid of divers. The paper will explain the special considerations that have to be made to allow for deepwater installation and intervention.

The final contributor to a successful subsea system is the quality of the equipment installed. Installation and intervention vessels are expensive, and therefore any failures can be costly not to mention the potential loss in revenue. Quality control and inspection are important, but no deepwater subsea project is installed without extensive integration testing. This paper will explain the extent of integration testing.

Introduction

The Scarab and Saffron fields are in the West Delta Deep Marine concession, which is located in the Eastern Mediterranean Sea offshore of the Nile Delta in Egypt.

The Burullus Gas Company is developing the fields, which is a joint venture between EGPC (Egyptian General Petroleum Company), BG Egypt and Petronas.

The Burullus Gas Company project team are supported by the DMC (Deepwater Managing Contractor) a joint venture consortium between Bechtel and Intec Engineering with Intec personnel responsible for system engineering and the management of the three major offshore supply and installation contracts. The Deepwater Equipment is being supplied by EDDC (Egyptian Deepwater Development Consortium) a joint venture between Kvaerner Oilfield Products and Cameron, the umbilicals are being supplied by Nexans (formerly Alcatel) and the installation of the pipelines, umbilicals and deepwater equipment is by Stolt Offshore. Equipment manufacture is now almost complete and extensive testing is being conducted before its installation later this year.