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Japanese translation

Participation in the CCS Project at the Arthit Gas Field in Thailand

Oct. 22, 2025

Mitsui & Co., Ltd. (Head Office: Chiyoda-ku, Tokyo; President: Kenichi Hori; "Mitsui & Co.") has joined a Carbon Capture and Storage (CCS) project at the Arthit gas field in the Gulf of Thailand, operated by Thailand's PTT Exploration and Production Public Company Limited ("PTTEP"), through its wholly owned subsidiary, Mitsui Energy Development Co., Ltd. ("MOECO"). MOECO participates in the project via its subsidiary MOECO Thailand Co., Ltd., which holds a 4.7619% share in the CCS project. This project, the first CCS initiative in Thailand, aims to begin operations in 2028.

The Arthit gas field supplies approximately 8% of Thailand's domestic natural gas demand, and it is expected to store up to 1 million tons of CO₂ annually.

MOECO holds a 51.42% stake in its subsidiary MOECO Thailand Co., Ltd. which has held a 4% share in the Arthit gas field since 1998. In 2022, Mitsui & Co. and MOECO were selected for a support program by Japan's Ministry of Economy, Trade and Industry titled "FY2022 Infrastructure Development Survey Project for Bilateral Credit Acquisition (JCM Feasibility Study and CEFIA Domestic Secretariat Operations)," and have since conducted related studies. The outcomes of these studies have now led to a decision.

This CCS project represents an initiative in Mitsui & Co.'s efforts to achieve net-zero emissions by 2050. Furthermore, the project demonstrates high feasibility as a model for low-carbon energy businesses, as it achieves CCS without impacting existing natural gas production.

Since its establishment in 1969, MOECO has been engaged in exploration, development, and production activities around the world, primarily focusing on offshore operations in Thailand. Through its long-standing partnership with PTTEP, MOECO continues to contribute to Thailand's national goal of achieving carbon neutrality and promoting decarbonization.

Together with MOECO and other group companies, Mitsui & Co. will utilize its expertise cultivated through upstream oil and gas operations to promote the social implementation of CCS, thereby contributing to its goal of "building a foundation for sustainable and stable supply."

Project Overview of Arthit Gas Field

Name of block	Block 14A, 15A, 16A
Status	Producing
Partners	PTT Exploration and Production Public Company Limited (80%, Operator) Chevron Thailand Exploration and Production Ltd. (16%) MOECO Thailand Co., Ltd. (4%)

Mitsui’s Materiality

“Build brighter futures, everywhere” as our corporate mission, and to gain the trust and expectations of our stakeholders to realize a better tomorrow for earth and for people around the world, we have identified six material issues (“Materiality”) for Mitsui’s sustainable growth. We anticipate this particular project/ business to contribute especially to the realization of “Establish a foundation for sustainable and stable supply”