* New refinery will triple capacity to 360,000 bpd from 120,000
* Aims to conclude details on financing, partners early 2015 (Adds comments, details)
By Pisit Changplayngam and Khettiya Jittapong
BANGKOK, Aug 13 (Reuters) - Thailand's PTT Global Chemical Pcl said on Wednesday it is seeking a partner to expand the crude processing capacity of its planned joint petrochemical project with Indonesian state oil and gas firm Pertamina.
PTT Global is planning to triple the crude processing capacity of the project to 360,000 barrels a day (bpd), which would boost the estimated investment in the complex to as much as $8 billion, chief executive Bowon Vongsinudom told reporters.
PTT Global's initial plans with Pertamina had called for an investment of $5 billion in the petrochemical complex at Balongan on Java island.
The investment is part of PTT Group's plan to boost its presence in Southeast Asia as domestic demand slows after several months of political unrest that weakened the economy.
"The estimated investment is expected to rise to $7 billion-8 billion. It's huge money. PTTGC will focus on petrochemicals and we need to seek a partner to strengthen the refining part," Bowon said, adding the refinery will help supply feedstock to the petrochemical plant.
The company is studying details on how to finance the project and potential partners, a process it expects to conclude in early 2015. It aims to begin operations at the Indonesia complex in 2020, delayed from a previous completion target in 2018, Bowon said.
The complex will include a 1 million tonne olefins plant and a downstream polymer facility, and will supply the Indonesian market during initial stage of operations, the Thai firm said in a statement.
"Having a production base in Indonesia will provide us an opportunity to expand into other Southeast Asian markets," the statement said.
PTT Global, 49 percent owned by the country's top energy firm PTT Pcl, signed separate deals in 2013 with Pertamina and China's Sinochem Group to jointly develop petrochemical businesses in the two countries.
PTT Global produces ethylene and propylene, together called olefins, which are petrochemicals used to make plastic pellets used as raw materials in the packaging industry.
It has an olefins and aromatics petrochemical capacity of 8.75 million tonnes a year and a crude oil refining capacity of 280,000 bpd. Its five-year capital expenditure programme calls for investment of $4.5 billion over 2014 to 2018.
At 0830 GMT, PTT Global shares were up 1.16 percent, in line with a 1.1 percent gain of the overall market. (Writing by Khettiya Jittapong; Editing by Tom Hogue)