OSLO - Offshore services provider Ocean Installer said on Monday it had been hired to deliver installation services at Norwegian oil major Statoil’s giant Troll oil and gas field in the North Sea. The work, to be carried out in the spring and summer of 2016 on the Troll C platform under an existing framework agreement, includes both subsea and topside disconnection and removal of the platform’s existing risers, and the installation of new risers, it added. The risers, a type of flexible pipelines, are used to bring oil and gas from the seabed to the platform. Norwegian gas system operator Gassco last week said production of gas at Troll would be shut from May 28 to June 9. Ocean Installer, which is owned by private equity firm HitecVision, will use the Normand Vision construction support vessel for the work. The ship is owned by Solstad Offshore . The Statoil contract included options for work at the Vigdis oilfield, Ocean Installer added. (Reporting by Terje Solsvik; Editing by Biju Dwarakanath)