* Oman's Overseas Oil and Gas LLC (OOG) is actively looking for new partners to develop $15 billion new refinery in Bontang, East Kalimantan, OOG Chairman Khalfan Al Riyami told reporters on Monday
* OOG is currently in discussion with Japan's Cosmo Oil International, a unit of Cosmo Energy Holdings, while looking for more investors "because it is a big project", Al Riyami said
* OOG currently controls 90 percent of the project and Indonesian state energy company PT Pertamina controls 10 percent
* He said the cost of the project, which consist of a refinery and petrochemical plants, is $15 billion. Pertamina initially estimated the project cost at $10 billion
* The company aims to decide on financing source of the project within five months, Al Riyami said. The plant is scheduled to start operation around 2025-2026
* He added that OOG is also looking for more supply of crude oil for the 300,000 bpd refinery, preferrably from national oil companies
* OOG has signed memoranda of understanding with two local companies, PT Sanurhasta Mitra Tbk dan PT Meta Epsi Tbk, to build supporting facilities in Bontang, such as power stations, pipe infrastructure and water treatment for a combined value of $3 billion.
(Reporting by Wilda Asmarini, Writing by Fransiska Nangoy; Editing by Rashmi Aich) ((Fransiska.Nangoy@thomsonreuters.com; +62 21 2992 7610; Reuters Messaging: email@example.com))