Case History of the Cormorant Field Single Satellite Well
Authors: Brommer Jon J. , Fernandinho Carlos M.M.S. , Liles Joseph R. 
Published: October 2008

A single satellite subsea well in 500 feet water depth, producing 2 1/2 miles to separation facilities on the South Cormorant platform in the North Sea, has successfully proven the suitability of special equipment in overcoming some unique problems. Dual tubing strings and flow lines permits pumping through flow line (TFL) tools from the platform for downhole components maintenance. Additionally, other equipment such as electro-hydraulic controls with inductive couplers, methanol injection skid, remote driverless systems for flow line and control hook up to the well adapts concepts directly applicable to future long distance deeper water production systems. Buried insulated flexible flow lines have proved effective in avoiding potential wax and hydrate problems.

This paper is therefore a case history of the development of specifically tailor-made equipment and the experience gained from the installation and production from the first subsea well in the Central area of the Cormorant field. Emphasis is placed on development concepts and the equipment uniquely manufactured to meet special needs. A one year onshore integrated system test of the equipment is described along with the interface problems identified and resolved prior to going offshore. Actual installation and commissioning activities are fully covered including drilling, completion and production from the well.

The paper describes the major reasons for the success of the subsea well to date as being extensive onshore testing, detailed planning, and the early involvement of operating personnel. It will further conclude that using this type of project execution philosophy has proven invaluable in identifying and eliminating numerous interface and operational problems which would have proven to be a costly offshore lesson. The successful performance of this equipment and the high uptime of the well has proved the technical merits and suitability of using this type of equipment for future applications.

Introduction

In late 1974, Shell U.K. Exploration and Production and Esso Exploration and Production U.K. formed the Joint Underwater Development Team (JUDT) with the objective of developing an underwater production system suitable for use in the U.K. Sector of the North Sea. Both Shell and Esso contributed their "know-how", providing adequate technology and experience based on Shell's subsea satellite wells in Brunei and elsewhere and Esso's Submerged Production System pilot project in the Gulf of Mexico.

The basic project philosophy was to use as far as possible proven technology in developing a design which emphasized safety, reliability, flexibility and ease of maintenance. Naturally, prior systems did not sufficiently meet all our North Sea project criteria for flexibility and reliability and in-depth studies were undertaken by the team which are further described in subsequent sections.

A fundamental philosophy was adopted by the project that progress would proceed in a step-wise fashion as follows:Step 1Undertake development and installation of equipment for a single satellite subsea well.Step 2Use the experience gained to finalize development of equipment to serve future subsea satellite wells and to extend the concept to larger underwater systems having direct application in smaller field developments and for reaching reserves in water depths exceeding practical limits of conventional platform designs,