The world's first unmanned central production platform is on schedule to make its appearance in 1993.
Ste. Nationale Elf Aquitaine, Paris, has spent $34.5 million to develop key elements in an unmanned central system. The program consisted of reliability studies of existing equipment and developing and testing of new equipment.
Work on the project, designated Platine, began in 1986. The goal was to reduce operating costs by extending the satellite platform concept for drilling and first stage production processing to a full scale central production center that would need inspection and maintenance visits only once or twice a year.
Pierre Lefevre, Platine project manager, said pilot testing of equipment that would optimize process control and reliability of installations has now reached the stage at which an unmanned platform could be commercially available in 3 years.
However, the initial objective of one or two yearly visits has proved too optimistic. Platine has shown that 10 or 12 random 1 day visits/year would also be necessary.
The project has been funded in part by the European Community. Agip SpA, which operates unmanned platforms in the Adriatic Sea, has joined the project. Elf also is discussing the possibility of participation by BP Exploration. Early work on Platine showed that pilot projects to test upgraded equipment would be needed in well activation, production systems, sensors, rotating machinery, process control systems, maintenance, and safety and surveillance.
FIELD TESTS
An automatic gas lift start-up system with an electrically actuated gas flow rate control valve, an adjustable wellhead production choke, sensors, a fault tolerant programmable logic controller, and specific software has undergone tests off Gabon. The system hiked oil production considerably and reduced high pressure gas consumption by 25%.
Another pilot to optimize the gas distribution in gas lifted oil wells will get under way in Gabon early next year.
In the area of well pumping, studies have pinpointed unreliable components in long stroke pumps. Replacement components have been manufactured and are under test. The most reliable electric submersible pump also has been selected.
A pilot to improve the reliability of a conventional well safety system has been successfully operated in Gabon since October 1989, and optimum systems for fluid recovery from associated gas have been chosen.
A Comprehensive pilot engineering study for water injection treatment equipment has been completed, including distributed architecture of the control system and redundancy of the equipment.
To handle offshore water disposal, a prototype deoiling system made up of a hydrocyclone separator with a nonemulsifying feed pump, a specific coalescer, discharge tank with sump, and analyzers has been built. Pilot application is to get under way next year in Congo.
Studies showed that conventional separators could meet Platine specifications with some simplification.
Studies for automatic pigging of sea lines between satellite and central production platforms resulted in a patented system.
PLATFORM SENSORS
Platine also investigated platform sensors and discovered that 60% of faults were due to human intervention, 30% to packaging, and 10% to the measurement cell. Short term improvements to reliability were available, but in the longer term optical sensors were seen as the best solution. The reliability of bottomhole pressure and temperature sensors did not meet Platine standards because of poor behavior of electrical components at temperatures above 80-90 C.
In cooperation with Agip, a demonstration of an optical downhole sensor has been manufactured and is under test. A pilot, including surface unit, optical cable, connector, and sensor is to be installed in an Agip well at the end of 1991. A wide ranging survey of rotating equipment showed offshore reliability is much lower than onshore and that failures were due to peripheral components: instruments, lubrication, cooling, and filtration. In pumps and compressors, leakage was the main factor.
Platine studies show that instrument air should not be used, external lubrication should be suppressed, and reciprocating compressors should be avoided. A high speed, centrifugal compressor should be available for installation on site in 1992, and technologies not usually used in the oil industry have been chosen for various applications in pumping.
A pilot process control expert system for oil treatment is under development by Elf and Agip. A unit, including slug catcher, three stage separation, desalting, and crude stabilization is to be installed on site early in 1992, A demonstration model for gas dehydration also has been developed.
In the key area of safety and surveillance, a Platine control and safety system is being compared with the reliability of two independent systems.
An autonomous surveillance system, independent of the safety and control system, has been evaluated. It aims to identify, locate, and assess liquid leakage, marine pollution, human intrusion, shock, and explosion. The first unit will be installed shortly on a platform.
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