Tolmount East success

Premier Oil plc

("Premier")

Tolmount East success

17 October 2019

Premier is pleased to announce the success of the Tolmount East well, 42/28d-14, in P1330, Block 42/28d (Premier 50 per cent operated interest) in the UK Southern Gas Basin. The well was targeting 220 BCF of P50 gross resource, in an undrilled area four kilometres east of the 500 BCF Tolmount gas field.

The well penetrated 241 feet of gas bearing high quality Leman sands with a net-to-gross ratio of 71%, porosity of 16% and gas saturation of 82%. The quality and thickness of reservoir sands encountered are at the upper end of expectations and no gas water contact was penetrated. The reservoir section was successfully cored with 216 feet being recovered. A full Logging-While-Drilling and wireline acquisition programme was undertaken, including extensive pressure data and fluid sampling.

The well data will now be integrated with the new 3D seismic dataset as part of the fast-track development planning for Tolmount East. This is already well advanced ahead of project sanction targeted for 2020 2H. The well result is also positive for the additional potential identified in the Greater Tolmount Area, including Tolmount Far East and the Mongour discovery.

Tony Durrant, CEO, commented:

"We are delighted by the Tolmount East result, the development of which will add significant value to our UK portfolio. Elsewhere in the Greater Tolmount Area, we are making excellent progress with our sanctioned Tolmount development which remains on schedule for first gas by the end of next year and will add a net 20,000 to 25,000 boepd to Group production."

Enquiries

Premier Oil plc

Tony Durrant, Chief Executive

Robin Allan, Director North Sea and Exploration

Dean Griffin, Head of Exploration

Tel: 020 7730 1111

Camarco

Billy Clegg

James Crothers

Tel: 020 3757 4983