User:Andyminicooper/Argyll Oilfield

The Argyll field came on stream in 1975, representing the first oil production from the UK sector of the North Sea. The field located in block 30/24 of the UK Continental Shelf (UKCS), was developed by Hamilton Brothers Oil and Gas as operator who pioneered the use of the first Floating Production Facility (FPF) in the North Sea. Partners in the Block were: Blackfriars Oil and Gas Ltd; Hamilton Brothers Petroleum Corporation; Hamilton Oil GB plc; Kleinwort Benson Energy Ltd; RTZ Oil and Gas Ltd; and Texaco North Sea UK Co.

History
The field lies in Block 30/24, 190 miles southeast of Aberdeen, Scotland, and 25 miles southeast of Phillips Petroleum Co.'s Ekofisk field. The field was discovered in Aug. 1971 and was confirmed in 1972. The field was developed using a unique offshore production facility based on a semisubmersible drilling rig converted to a production platform. This is connected to sea-bed installations by a production riser developed by Hamilton Brothers for this application. The Argyll area comprises a complex geographical regime and as a result of further appraisal drilling two oil-bearing structures, later named the Duncan field, were discovered some four miles West of Argyll in 1980 and 1981. Phase 1 of the Duncan development plan brought this fie1d on stream in 1983, by the use of a subsea manifold tied back over a distance of 3½ miles to the existing Argyll Field Floating Production Facility (FPF), 'Transworld 58'. Phase 2 required the provision of a water injection programme for reservoir management and pressure maintenance. Due to payload limitations, it was not possible to achieve this by adding suitable facilities to the existing FPF. This led to the conversion of the H3-AC semi-submersible 'Deepsea Saga' to meet the totally Argyll/Duncan production requirements. The project to modify the drilling rig 'Deepsea Saga' into the FPF, 'Deepsea Pioneer' utilized a 'fast-track' approach, with a 6 month conversion period from start of work to departure for the Argyll F1eld. Detailed design engineering commenced on 12th December 1983, and first oil was produced on 20th November 1984. The basic process specification for the new FPF was a process system capable of handling 70,000 B/D of fluids and 14 million scfd of gas. The separation plant consisted of a single train with two stages of separation. A test separator to allow individual wells to be flow tested. The design to provide for 40,000 B/D of oil to be produced and exported via an Single Buoy Mooring (SBM) to a shuttle tanker. The field was abandoned in 1982, but production redevelopment was considered by two UK companies in 1982.

Geology
The Argyll field is one of the few Permian fields discovered in the North Sea. The main productive zone is a Zechstein dolomite underlain by a Rotliegendes sandstone. The Zechstein crude is 38 degrees API gravity, and the Rotliegendes is slightly lower at 34 degrees. Sulphur content in the field is around 0.25 percent and wax content averages 6 percent. Gas Oil Ratio (GOR) ranges between 150 and 300 scf/bbl The Argyll field is a relatively small field drained by a few wells. It is considered probable that good communication exists between the sandstone and dolomite. Because of the relative complexity of the Argyll geology was not easy to predict how the field would produce. These considerations led Hamilton Brothers to choose a test production facility for the initial phase of development of the Argyll field. The program was designed to place the field in production with minimum investment and to yield reservoir information required to determine future development policy. At the same time, this production test would yield sufficient revenue to assure profitable initial operation of the field.