A prototype Oil-Gas Production Separation Unit, with ancillary equipment typical of that on most process vessels, has been developed and fabricated for operations tests this summer on the sea-floor at an oil well in the Zakum Field in the Arabian Gulf. This paper describes the submerged processing unit in detail as well as the previously reached conclusions which led to its particular design and test philosophy. Also described in summary is the total Zakum subsea test program of Compagnie Francaise Des Petroles and British Petroleum, of which the production processing unit test is a part.
This production processing unit can set itself on bottom after being towed to location and is retrievable back to the surface. Gamma ray level controls, a thermo-electric power generator, hydraulic flow line connectors with integral block valves, and a variety of other ancillary devices will be tested on this 15,000 barrel per day oil stream.
Any consideration of oil and gas production from operating centers located beneath the air-sea interface involves a totality of interrelated factors certainly as broad and deep as the ocean itself. The rather complex overlap of data and decisions required, for instance, only to derive a basis for design is shown schematically on Fig. 1. Obviously, there is no reasonable way to isolate any one element of the total problem from all the rest.
A limitation of scope is nevertheless required in a specific study or discussion. So, for purposes of this paper, observations are limited to matters relating only to an initial oil and gas processing facility itself. This is the facility which lies between the termination of the well effluent gathering system and the discharge into the processed fluids disposition system. Both from the standpoint of investment and overall technology, this may be a minor part of the total submarine oil and gas producing system. However, this minor part is always the vital "heart element," so to speak.
Much theoretical study work relating to submerged oil and gas production processing facilities has been done in the last few years by producers, marine construction contractors, aerospace firms, and process system manufacturers. The primary emphasis has, of course, been on unique or novel design arrangements which appear to meet the requirements of the wet and pressured environment. Much work has also been done to create adaptations of existing techniques and equipment to fit a submerged environment. This latter work, while less publicized, may indeed be more immediately valuable to the industry even than the novelties.
In some instances, the theoretical studies have led to models being built and tested in a wet environment as well as plans being developed for appropriate simulations. However, most modeling has been conceptual in nature and productive simulation work depends on further quantification of the problem elements.
Out of the studies and modeling, and based on today's state of the art, several basic requirements have become apparent insofar as the production processing element of a totally submerged oil and gas producing system is concerned.