High-impact offshore block duo helping unlock Southeast Asia’s deepwater gas potential

October 8, 2025, by Melisa Cavcic

UK-based and AIM-listed Sunda Energy, formerly Baron Oil, has expanded its offshore footprint by securing a non-operated stake in two offshore petroleum blocks in the Sulu Sea, as part of license awards that are a direct result of the joint applications submitted by the bid group composed of Triangle Energy, Sunda Energy, PXP Energy Corporation, and Philodrill Corporation.

As part of the joint venture, led by Triangle Energy (37.5%) and including PXP Energy (12.5%) and Philodrill (12.5%), Sunda Energy won a 37.5% non-operated interest in two petroleum service contracts for offshore license areas in the first Conventional Energy Bid Round in the Bangsamoro Autonomous Region of Muslim Mindanao (BARMM) in the Philippines.

This is interpreted to mark a significant step in unleashing Southeast Asia’s gas potential. The commitment work programs in the first two-year sub-phase of the service contracts entail 2D and 3D seismic reprocessing and associated geological studies for two blocks, SC-80 (formerly PDA-BP-2) and SC-81 (formerly PDA-BP-3).

The first block’s estimated combined 1C contingent gas resources are 1811-2212 billion cubic feet (bcf), 2C contingent gas resources of 4701-5742 bcf, and 3C contingent gas resources of 1,3171-2,5042 bcf, with estimated Pmean prospective gas resources of 10,0882 bcf. Located in the southwest part of the Sulu Sea, within the Sandakan Basin, the blocks lie in water depths of less than 100 meters to greater than 3,000 meters.

The SC-81 prospective trend is said to be covered by several 3D seismic surveys with several seismic anomaly-supported prospects and leads. Sunda claims that these assets diversify its asset base, whilst offering potential for value creation via possible farm-out and carried high-impact drilling, with limited upfront investment.

Location of Sulu Sea blocks SC-80 and SC-81; Source: Sunda

Dr. Andy Butler, Sunda’s Chief Executive Officer, commented: “We are delighted to have been awarded these two Service Contracts and extend our thanks to the Philippines and Bangsamoro authorities. These assets offer Sunda the potential to uncover high impact appraisal and exploration targets which should be of interest to major E&P players.

“We’re excited to return to an area that the Sunda team knows well and where the potential for vast energy resources is undoubted. We look forward to working closely with Triangle and our other joint venture partners as we leverage the extensive data set that exists to set about unlocking that potential quickly and at relatively low cost.”

The main play is Upper Miocene turbidite sands trapped in toe-thrust anticline structures and basin floor stratigraphic traps in the deepwater areas, whilst secondary prospectivity exists in Middle to Upper Miocene shallow water sandstones in the western shallow water areas and in deeper Miocene carbonate reef features.

SC-80 covers much of the area of a former SC 56, where members of the Sunda team gained extensive knowledge working with a previous operator, Mitra Energy. ExxonMobil came aboard and drilled four exploration wells in the deepwater fold belt play in 2009-2010, finding two significant gas fields with the Dabakan-1 well with 75-meter net pay and Palendag-1 wells with 47-meter net pay, alongside a minor gas discovery at Babendil-1 with 39-meter net pay.

The U.S giant exited in 2011, although TotalEnergies farmed into the block a year later and acquired additional 3D seismic data, committing to drill the giant Halcon prospect, a low relief, anticlinal structure interpreted to be a basin-floor turbidite fan sandstone complex trapped against the frontal thrust of the fold-belt, with estimated Pmean prospective gas resources of 6,735 bcf.

Seismic structural section illustrating Sulu Sea discoveries and plays; Source: Sunda

However, the French player canceled drilling plans following management and strategic changes in 2016, and the block was relinquished in 2020 without further drilling. With Halcon remaining undrilled, and many other gas prospects on trend, Sunda believes that there are significant prospective resources to pursue on the block, already derisked through existing discoveries.

On the other hand, SC-81 lies adjacent to and south of SC-80 and encompasses both a slope clastic play and a shallow water shelf play. Two wells have demonstrated the presence of hydrocarbons: Wildebeest-1 recovered oil samples from thin sands and Lumba Lumba-1 encountered significant hydrocarbon shows but was abandoned early due to anomalous pressures.

With this in mind, Sunda and its joint venture partners consider that these earlier wells were poorly located since they missed key target areas, as prospective areas appear to be associated with seismic amplitude anomalies, though neither well targeted such an anomaly. Most of the prospective trend on the slope is covered by 750 square kilometers of 3D survey acquired in 2007, on which several seismic anomaly-supported prospects and leads have been identified.

In addition, multiple carbonate reef buildups have been spotted, which represent extra potential exploration targets like those that have proven highly prospective elsewhere offshore Borneo and globally. Five wells have been drilled in the shelf area of SC-81, and all were dry or had minor gas shows. This area is consequently considered less prospective, although five discovered fields in the neighboring Malaysian waters indicate some gas potential.

Summary map illustrating discoveries and prospective features in SC-80 and SC-81; Source: Sunda

Sunda underlined: “The geological environment of the two new service contracts, the presence of extensive 3D seismic data, and good calibration from a number of wells, make this area ideal for the deployment of modern seismic imaging technologies.

“The significant earlier investments made by ExxonMobil, and later Total, in these data, create a great opportunity for Sunda and its joint venture partners to deploy special processing techniques to properly delineate the gas discoveries and further de-risk the material exploration prospectivity.”

This low-cost approach is anticipated to reveal high-impact appraisal and exploration targets for farm-out and future drilling. The commitment work programs in the early stages of the seven-year exploration term consist principally of seismic reprocessing and desktop studies, with two optional wells in each service contract in the final three years.

Commitments in the first two-year sub-phase of the PSC for the two blocks encompass 3D and some 2D seismic reprocessing, and associated geological studies. Sunda elaborates that the Philippines’ service contracts are similar to production sharing contracts in other countries, with fiscal terms that are favorable by international standards.

The seven-year exploration phase is divided into sub-phases with separate work program obligations, but the service contract can be surrendered before proceeding to the next sub-phase if the work obligation is fulfilled.