This paper presents a review of the development status of three subsea oil production systems under development by Subsea Equipment Associates Limited (SEAL). This international consortium owned by Bristish Petroleum, Compagnie Francaise Des Petroles, Groupe DEEP, Westinghouse and Mobil Oil Corporation, is presently testing two production systems designed for primary use in foreign fields. These systems should find application in the water depths greater th'an 150 feet with average well production ranging from 1, 000 to 10, 000 barrels per day. SEAL is also testing a subsea oil production in the Gulf of Mexico which is designed primarily for utilization with large numbers of domestic low-production wells which in turn generally require significant maintenance. Participating in these test projects from anon-owner standpoint are Continental Oil Company, Phillips Petroleum, Sun Oil Company and ELF/ERAP.
The SEAL Intermediate System (SIS) is described with particular emphasis on utilization of a Manned Working Enclosure (MWE) to permit men to perform maintenance operations in a dry environment at the sea floor. The MWE concept involves lowering the structure over the wellhead, expelling the water and transferring personnel by the use of a Personnel Transfer Bell (PTB). The status of this development project is reviewed.
The SEAL Shallow System is described including a review of present testing off the South Coast of France. This concept is similar to the MWE with the exception that the maintenance personnel are carried in the SEAL Bell. Once the bell is pulled to the subsea wellhead, water is expelled and the atmospheric pressure reduced to sea level to permit the men to enter the work chamber and perform the necessary operations.
The SEAL Atmospheric System is described in some detail in this paper. This system concept is based on the use of a large habitat-type structure permanently installed on the sea floor to house oil field equipment. Future applications of this concept would be as a manifold center, a test separator center or a complete oil production system. In a similar manner to the other systems, men are transported to and from the Subsea Work Enclosure (SWE) through the use of a Personnel Transfer Bell. In addition to the description of the production SEAL Atmospheric System this paper presents a review of the present test installed in the latter part of 1972 and details are presented on the installation of the base structure, the Subsea Work Enclosure and the Wellhead Connection Assembly. The present status of this test program is also presented together with plans for the future.
A common element in each of the three systems being developed by SEAL is the use of a Personnel Transfer Bell to transport maintenance workers to the subsea structure in a safe and efficient manner.
