Golden Sea Lion roars with appraisal success at oil discovery offshore Southeast Asia

January 7, 2026, by Melisa Cavcic

Houston-based oil and gas company Murphy Oil has achieved a new appraisal milestone related to an oil find in the Cuu Long Basin approximately 40 miles off the coast of Vietnam, Southeast Asia. This move is perceived to have unlocked significant resource upside.

An offshore rig — Illustration; Source: Murphy Oil

While shedding light on the drilling of the Hai Su Vang-2X (HSV-2X) appraisal well in Block 15-2/17 in the Cuu Long Basin, Murphy explained that the well, which was spud in early October 2025, marked “a major milestone” in its strategic appraisal campaign for the Hai Su Vang (Golden Sea Lion) field.

As it appraised the 2025 Hai Su Vang discovery, which encountered approximately 370 feet of net oil pay across two reservoirs, the HSV-2X well encountered 429 feet of net oil pay across the same two reservoirs, including 332 feet of net oil pay in the deeper primary reservoir and 97 feet of net oil pay in the shallow reservoir.

Eric Hambly, Murphy’s President and Chief Executive Officer, commented: “This is a pivotal moment for our Vietnam business. The success of HSV-2X not only reinforces the commerciality of the Hai Su Vang field but also sets the stage for a robust development program. We are proud of our team’s execution and remain committed to working closely with our partners and the Vietnamese Government to unlock the full potential of this asset.”

According to the company, the HSV-2X appraisal well deepened the proven oil-down-to by 413 feet without encountering water, extending the total hydrocarbon column to approximately 1,600 feet within the primary reservoir, with formation evaluation supporting reservoir continuity to the HSV-1X discovery well.

Murphy finds oil pay offshore Vietnam

Exploration & Production

The firm emphasized that the primary reservoir achieved a production rate of 6,000 barrels of oil per day during flow testing of the appraisal well. While the well produced high-quality, 37-degree API oil, which is consistent with the results from the discovery well, further testing is ongoing.

Murphy underscored: “These results confirm Hai Su Vang as a significant discovery and inform an updated range of recoverable resources for the field. The updated midpoint of recoverable resources for the primary reservoir is towards the high end of our previously communicated range of 170 to 430 MMBOE and the high end of the new range now exceeds 430 MMBOE.

“Additionally, results from the shallow reservoir provide recoverable resource upside not included in the previously communicated range. Additional appraisal wells are necessary to further refine the range of recoverable resources for both reservoirs.”

Upon the completion of HSV-2X operations, the firm will continue its strategic appraisal campaign to further delineate the field and evaluate additional reservoir intervals with the HSV-3X appraisal well in Block 15-1/05, and the HSV-4X well in Block 15-2/17.

The company also reaffirmed its previously stated CAPEX guidance of $1.1–$1.3 billion for 2026. Murphy’s subsidiaries, Murphy Cuu Long Tay Oil and Murphy Cuu Long Bac Oil, serve as the operators of Block 15-2/17 and Block 15-1/05, respectively, holding a 40% working interest in each block.

PetroVietnam Exploration Production Corporation has a 35% working interest in each block, and SK Earthon holds the remaining 25% stake. Murphy has other assets in Vietnam, including the Lac Da Vang (Golden Camel) field development in Block 15-1/05.

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The company decided to proceed with the project in 3Q 2023 and hired PTSC Asia Pacific, which is a joint venture between Yinson Production and PetroVietnam Technical Services Corporation (PTSC), for the provision, charter, operation, and maintenance of a floating storage and offloading (FSO) unit in December 2024.

PTSC Mechanical & Construction wrapped up the load-out of the Lac Da Vang – A (LDV-A) platform jacket and piles in September 2025. The first oil is targeted for 4Q 2026, with development anticipated to continue through the financial year 2029.