Use of Unmanned Platforms in an Offshore Environment

Abstract

Summary This paper summarizes operating experience with unmanned productionfacilities 100 miles [160 km] offshore in the South China Sea. productionfacilities 100 miles [160 km] offshore in the South China Sea. The 11 unmannedsatellite platforms currently in operation produce to a manned centralprocessing platform (CPP), where major processing and compression facilitiesare concentrated. The evolutionary development of this central/satelliteconcept provided significant savings in capital and operation cost. Introduction Esso Production Malaysia Inc. (EPMI) has petroleum operations offshoresoutheast Asia in the South China Sea, as shown in Fig. 1. Approximately 100miles [160 km] off the coast of peninsular Malaysia, producing fields are inwater depths of about 200 ft [60 m]. EPMI, acting as a contractor to PetroliamNatl. Bhd. (Malaysia's national oil company), started oil Petroliam Natl. Bhd.(Malaysia's national oil company), started oil production in peninsularMalaysia in 1978. The 24 off-shore platforms form production in peninsularMalaysia in 1978. The 24 off-shore platforms form a network capable ofproducing more than 350,000 B/D [55.6x 10 3 m3/d] oil through a subseatrunkline to an onshore crude stabilization and exporting terminal. Theplatforms can be divided into three types: CPP's and manned and unmannedsatellite platforms. As Fig. 2 shows, until mid-1988, there were eight CPP's, four manned satellites, and nine unmanned satellites; a pumping platformconnected to a manned satellite by a bridge is not pumping platform connectedto a manned satellite by a bridge is not included in this total. Three moreplatforms (one CPP and two unmanned satellites) were installed in late 1988 and1989 (not shown in Fig. 2). Distances between the satellites and the CPP's varyfrom l to 9 miles [1.6 to 14.5 km]. The CPP's act as the focal points for field development and have oil-water-, and gas-processing facilities. Oil-processing facilities include two or threestages of crude separation, after which the dewatered crude is pumped to shoreby the pumping platform. Produced water is treated to remove residual oilbefore being discharged to the sea. Gas-processing facilities to meetgas-injection, gas-lift, and gas-sales requirements include compressionturbomachinery and dehydration systems. Other utility systems areturbine-powered generators, freshwater-making units, instrument-aircompressors, and gas-flaring facilities. Manned satellites were an early development concept. This type of platform, where facilities are operated continuously, offered an economical platform, where facilities are operated continuously, offered an economical means ofproduction and training before unmanned satellites evolved. Facilities on theseplatforms include one stage of crude separation for metering purposes, equipment to treat produced water, and utility systems similar to those on theCPP's. These platforms do not have crude-pumping facilities and require minimalstaffing. Unmanned satellites were introduced as additional offshore operatingexperience was gained. Facilities are kept to a minimum to allow unattendedoperations. The current generation of unmanned platforms has remotewell-testing equipment, a test separator, and air compressors. Subsea cablesprovide electrical power and remote control. Unmanned Satellites First introduced in 1979, unmanned satellites became increasingly importantin later field developments. They provide a cost-effective means for developingand producing major and minor fields. Their usefulness is further substantiatedby very good operating experience, especially reduced operating costs andstaffing, compared with the initial manned satellites. The benefits that unmanned satellites offer are best illustrated by thedevelopment of the Guntong, Tabu, and Palas oil fields. Fig. 3 shows the sevenplatforms required for the initial development of these fields. This initialdevelopment involved installing a CPP--Guntong A--and four unmannedplatforms--Tabu A, Palas A, and Guntong B and C--all of which produce toplatforms--Tabu A, Palas A, and Guntong B and C--all of which produce toGuntong A. As Fig. 3 shows, two other platforms are planned for the future. Production from these fields started in late 1985 and early 1986. Developing these fields with all manned satellites, with centralized oil, water, and gas processing at Guntong A, would have required a capitalinvestment of about $440 million, a crew of 224, and $27 million in annualoperating costs. By comparison, the use of unmanned satellites requires acapital investment of about $300 million, a crew of 124, and about $20 millionannually to operate all the platforms. Savings of about $140 million in capitalcost and $7 million annually in operating cost can therefore be attributed tothis concept. Crews are reduced by 100 because of the concentration ofexperienced and skilled personnel at one central location. JPT P. 662