SPECIAL FOCUS: OFFSHORE REPORT

First subsea dual-ESP development tied back to an FPSO

Santos batch-installed Mutineer-Exeter field completions, saving 30% completion time from first well to last.

Peter Dodd, Santos Ltd; Ian Ayling, Howard Butcher, and Steven Brennan, Baker Hughes Centrilift

The Mutineer and Exeter fields in the Canarvon basin offshore Western Australia were developed using subsea production wells with dual Electrical Submersible Pumps (ESP) in four wells and a mudline Multi-Phase Pump (MPP) in each field. Dual ESPs were selected to ensure maximum well availability and flexibility. Using MPPs, Santos could reduce ESP horsepower and have a phased production approach.

Production from each well is commingled at the MPP suction manifold in each well center and produced through a flexible riser to an FPSO stationed 7 km from Exeter and 3 km from Mutineer in 160 m of water.

The Mutineer-Exeter development is 150 km offshore, north of Dampier in Western Australia within the WA 191-P exploration permit, operated by Santos Ltd. with partners Kufpec Pty Ltd., Nippon Oil Exploration Pty Ltd., and Woodside Energy Ltd., Fig. 1. The project was Santos’ first offshore field development.

The fields are about 10 km apart with the smaller Exeter to the southwest of Mutineer. The oil is 43° API crude with a very low Gas-Oil Ratio (GOR) of about 10 cf/bbl. Hydrocarbons are in faulted traps of the Jurassic, Upper Angel sandstone. Wells are normally pressured with 4,500-psi reservoir pressure at 3,100-m MD TVD. Bottomhole temperature is 106°C (222°F). There is 0.5 mol% CO₂ and <10 ppm H₂S in associated gas. Productivity ranges from 50 to 90 bfpd/psi drawdown.