Bundles and towed installation

Bundles and towed installation

51

SURFACE TOW

OOOGURUK BEAUFORTSEA

OOOGURUK – BEAUFORT SEA

ƒ Flatpack bundle in very shallow water ƒ Wells drilled from man-made offshore island ƒ 2.7 m (9 ft) deep trench 9 km (5.6 miles) long

ƒ Backfill protection against uplift, strudel scour and gouging

ƒ Pipe-in-pipe flowline ƒ Annulus vacuum and pressure monitor

Gas injection

Spacer

Diesel fuel

Trench to shore

Water Oil Gas

Concrete

Insulation

Water injection

P-I-P flowline

Pioneer’s Oooguruk field development is in Harrison Bay of the Beaufort Sea, North Slope, Alaska. Some 40 wells were drilled during 2007 from a 7 m (23 ft) high island standing in less than 1.5 m (5 ft) of water some 9 km (5.6 miles) from shore. Approximately half of the wells are producing wells and half are water injection wells. First oil was in June 2008. The 2.4 ha (6 acre) island was constructed during the coldest months by trucking gravel on an ice haul road built over the frozen sea. The flatpack (or open) bundle takes the production fluids ashore and supplies water and gas injection facilities plus diesel fuel to the island. The flowline is 323.8 mm by 406.4 mm (12¾ in by 16 in) pipe-in-pipe. This and the other lines are connected with 250 mm (10 in) wide spacers at 6 m (20 ft) intervals. Pioneer employs an annulus vacuum monitor or pressure monitoring system for environmental protection. The inside of the internal pipe operates at about 40 bar (580 psi); hence if high pressure is detected in the annulus then an internal leak has been detected. If low pressure is detected, this signifies a potential external leak. All lines are grade L360 (X52) or higher for compatibility with potentially high operational strains.