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Thailand’s 2026 Energy Outlook: Critical Reserve Data & the Race to the Andaman (Thailand)

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February 2026

Thailand’s 2026 Energy Outlook: Critical Reserve Data & the Race to the Andaman (Thailand)

Author: Supasit Boonsanong, Kobchai Nitungkorn (Co-author)

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Publisher: Nagashima Ohno & Tsunematsu

Journal / Book: NO&T Thailand Legal Update No.43(February, 2026)

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*Please note that this newsletter is for informational purposes only and does not constitute legal advice. In addition, it is based on information as of its date of publication and does not reflect information after such date. In particular, please also note that preliminary reports in this newsletter may differ from current interpretations and practice depending on the nature of the report.

Introduction

For decades, the Gulf of Thailand has been the bedrock of national energy security. However, recent data has forced a decisive strategic pivot. Facing a tightening reserve outlook, the Department of Mineral Fuels (DMF) has signaled that the future lies not just in maintaining the current reserves, but in opening a new frontier.

While immediate onshore contracts are being finalized, the defining narrative for 2026 is the impending 26th Petroleum Concession Round. This initiative represents Thailand’s major policy shift in years, unlocking the deep waters of the Andaman Sea to secure the nation’s long-term energy baseline.

This newsletter analyzes the Andaman opportunity, decodes the critical reserve data driving this urgency, and updates you on the immediate onshore awards and regional joint developments.

The 26th Concession Round: The Andaman Frontier

With mature fields in the Gulf of Thailand naturally declining, the DMF is turning its attention west. The launch of the 26th Concession Round is designed to attract investment into the Andaman Sea.

This region is viewed as a high-potential “blue ocean” for investors. The optimism is grounded in geological data, the area shares similar structures with neighboring Malaysian waters, where significant petroleum deposits have been discovered.

The government’s objective is to discover large-scale gas resources to serve as a new domestic baseload. Recognizing the higher capital requirements of deep-water exploration, the DMF is preparing a framework that balances significant investment commitments (estimated at THB 300 – 1,200 million per block) with the potential for major discoveries. By offering acreage adjacent to proven petroleum systems, Thailand hopes to attract major international players capable of deep-water operations.

The Catalyst: Why 1P vs. 2P Reserves Matter

The urgency behind this new round is driven by a significant data release from the latest Ministry of Energy data. To understand the government's aggressive stance, one must look at the difference between 1P and 2P reserves.

As of the end of 2024, Thailand’s natural gas status is as follows:

1P (Proven Reserves) – 4.6 Years Remaining:
“1P” refers to reserves with a 90% confidence level of being commercially recoverable. The fact that only 4.6 years of guaranteed supply remain is the primary driver for the accelerated concession rounds. These reserves represent the nation’s immediate energy security.
2P (Proven + Probable) – 8.3 Years Remaining:
“2P” includes both proven reserves and “probable” reserves, which have a 50% confidence level. While an 8.3-year timeline offers some buffer, it relies on resources that are not yet fully secured.

For national energy planning, the distinction between proven and probable reserves is material. The primary objective of the 26th Round is to de-risk the country’s supply outlook, converting geological potential into commercial certainty to extend Thailand’s guaranteed production runway well beyond the 2030s.

The Strategic Anchor: Thailand-Malaysia Joint Development Area (MTJDA)

While the Andaman Sea represents the future, the Thailand-Malaysia Joint Development Area (MTJDA) remains the critical safety net for the present.

To ensure supply continuity, the DMF is fast-tracking the Cabinet approval for Block A-18-01. This project is massive in scale, projected to mobilize approximately USD 8 billion in total investment.

The project is expected to generate direct revenue of USD 3.9 billion for the Thailand-Malaysia Joint Authority. This zone provides the essential baseload gas volume required to stabilize the grid while exploration in the Andaman progresses.

The Immediate Relief: The 25th Concession Round (Onshore)

Parallel to these offshore mega-projects, the government is moving quickly to harvest accessible onshore resources. The DMF is preparing to submit the results of the 25th Concession Round to the new Cabinet for approval.

The round has attracted five bidders submitting eight requests for onshore exploration rights. These projects are expected to generate THB 2.5 billion in immediate investment. Development of these fields could unlock an estimated 5.76 million barrels of crude oil and 20.7 trillion cubic feet of natural gas.

The Regulatory Unlock: Breaking the 10-Year Renewal Barrier

Beyond new acreage, the legal framework is evolving to maximize recovery from existing assets. A key development is the draft amendment to the current Petroleum Act, which seeks to remove the single 10-year renewal limit. This change is intended to prevent production gaps like those experienced during the Erawan field transition and provide concessionaires with the certainty needed to invest in aging fields such as Sinphuhorm and Sirikit.

The market shift from maintenance to exploration requires a recalibrated legal strategy. Whether you are an operator eyeing deep-water blocks or a service provider scaling for the MTJDA, our Energy & Infrastructure Practice supports every phase of this transition. We have the experience assisting several operators with their bid packages, ensuring alignment with the DMF’s latest scoring criteria while modeling the fiscal nuances of the “Thailand III/IV” PSC terms.

Simultaneously, for clients navigating market entry via farm-ins or M&As, we are conducting due diligence on title validity and relevant obligations. Beyond new entries, we are actively advising concessionaires on how regulatory shifts impact the economic lifespan and their existing portfolios.

If you would like to discuss how these legislative and commercial developments affect your business, or explore opportunities in the upcoming concession rounds, please contact Kobchai Nitungkorn at kobchai.n@nagashima.com.

February 20, 2026

This newsletter is given as general information for reference purposes only and therefore does not constitute our firm’s legal advice. Any opinion stated in this newsletter is a personal view of the author(s) and not our firm’s official view. For any specific matter or legal issue, please do not rely on this newsletter but make sure to consult a legal adviser. We would be delighted to answer your questions, if any.

Download full text（PDF）

Lawyers

Supasit Boonsanong

Partner

Bangkok

Kobchai Nitungkorn

Associate

Bangkok

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