Siam Moeco Ltd. (100 % subsidiary of MOECO) commenced the first oil production from Block L11/43 onshore Thailand

July 2, 2012 Project

Mitsui Oil Exploration Co., Ltd ("MOECO") announced today that Siam Moeco Ltd. ("SML"), a wholly-owned subsidiary of MOECO has successfully commenced its first oil production from the Block L11/43, onshore Thailand on June 29.

This is MOECO's first overseas operator project. SML acquired 100% interest of Blocks L10/43 and L11/43 in January 2004 by signing a concession agreement with the Thai government. In March 2007, SML farmed out 30% of its interest to GS Caltex Corporation of South Korea and has jointly conducted exploration activities. SML has confirmed several oil reservoirs through 6 and 5 exploration and appraisal wells in Block L10/43 and Block L11/43, respectively. As the long term production test results showed that it was feasible to develop, SML made the final investment decision for Burapa-A area of Block L11/43 in March 2011. An additional 5 development wells were drilled in early 2012, culminating in SML's start of the oil production.

The oil production rate from 7 production wells in Burapa -A is expected to be 2,000 barrels per day.

MOECO has been engaged in oil and gas exploration, development and production business in Thailand for more than 40 years. MOECO's long experience in Thailand has led to SML's first oil production as an operator. MOECO has positioned Thailand and other parts of South East Asia as its core area and aims to expand its business and pursue further acquisition of new operator projects in this region.