(Sharecast News) - Independent oil and gas company RockRose Energy has signed a share purchase agreement to acquire 100% of Marathon Oil UK, and 100% of Marathon Oil West of Shetland, from subsidiaries of Marathon Oil Corporation, it announced on Monday.The London-listed firm said the consideration payable by RockRose to Marathon Oil would be around $140m, subject to customary adjustments, which it currently anticipated being funded through existing resources and facilities.Marathon Oil UK holds operated interests of between 37% and 40% in fields in the Greater Brae Area, and Marathon Oil West of Shetland holds a 28% interest in the BP-operated Foinaven Field unit, and a 47% interest in Foinaven East.The acquisition also included interests in the SAGE, Brae-Forties and WASPS infrastructure, providing additional tariff income.Upon completion, RockRose said the acquisition was anticipated to add around 35 million barrels of oil equivalent (boe) of 2P reserves, or 21 million boe on a 1P basis.That would give the company a net 2P position on completion in excess of 70 million, and 2P+2C of 86 million boe.Anticipated production for the assets being acquired was around 13,000 barrels of oil equivalent per day (boepd) in 2019, taking RockRose's total net anticipated production for 2019 to about 24,000 boepd.The effective date of the acquisition would be 1 January 2019.RockRose said the Marathon Oil UK and Marathon Oil West of Shetland assets and teams in Aberdeen, Peterhead and offshore would transfer with the two companies to RockRose on completion of the transaction."This acquisition marks a major step change in the group's reserves and production profile," said RockRose executive chairman Andrew Austin."Given the quality of these assets the Board's view is this is a good opportunity to make the transition to the role of operator."We look forward to welcoming Marathon Oil UK employees, who have an excellent track record operating in the North Sea, to the RockRose team at closing."