Block 9/11a Mariner (Licence P0335)
(Nautical 6%)

Operated by Statoil Hydro ASA and located on the East Shetland Platform, west of the Viking Graben, the Mariner oil accumulation, discovered in 1981 and appraised with 15 subsequent well penetrations, is the largest, most highly appraised undeveloped discovery in the UKCS. These wells have tested oil at 1,000 to 1,595 bopd from both the Palaeocene Maureen Sandstone and the shallower Heimdal Sandstone. Both sands have excellent reservoir characteristics and, during an extended well test (EWT) in 1997, a single horizontal well in the Maureen Sandstone produced 662,000 barrels of oil over 63 days at a maximum rate of 14,991 bopd (14.5º API).

Interpretation and integration of the subsurface seismic and geological data have enabled the operator to construct geological models for the Heimdal and Maureen reservoirs. The improved understanding of the field has allowed the subsurface development plan to be optimised, particularly with regard to well design and well placement. The Maureen reservoir will be developed using single branch long horizontal wells whilst deviated multi-lateral wells will be used to develop the shallower Heimdal reservoir. The Maureen wells will be drilled first as they are expected to produce at initial individual rates in excess of 20,000 bopd. Drilling of the Heimdal reservoir will be scheduled to maintain the production profile and wells will be located on a close spacing to obtain a high recovery factor. This optimised development has resulted in a substantial increase in resources with our latest estimate being up to 430 mmbo (26 mmbo net) recoverable for both the Maureen and Heimdal reservoirs.

The operator has screened a number of different development concepts. The preferred concept of a steel jacket (PDUQ) with a single drilling rig, floating storage and oil transportation by shuttle tanker has been agreed. A contract for pre-Front End Engineering and Design (FEED) studies has been awarded. This will be followed by FEED and an Environmental Impact Assessment (EIA) which will be completed in 2012. Project sanction by the field partners and FDP submission is scheduled for Q4 2012 with first oil expected in 2016.

In November 2010, the Company completed the sale to Statoil of a 20.6667% interest in Mariner for total consideration of £87.5m. Additionally Statoil will provide a maximum £3.0m carry of the Company’s cost through to final investment decision.