Reserves rise at Yumna Field in Oman’s Block 50

Masirah Oil Limited (MOL), the operator of Block 50—currently the only producing licence off Oman’s east coast—has announced a notable increase in the reserves potential of its flagship asset – the Yumna Field.

Citing an independent Qualified Person’s Report issued in February this year, the company’s majority shareholder, Rex International Holding, estimates remaining gross 2P (proved + probable) reserves at 7.2 MMstb (million stock tank barrels), based on projected output from existing wells and the planned drilling of three additional development wells in 2026. These measures are expected to lift the recovery factor to 55 per cent ahead of the field’s economic cut-off, currently forecast for 2030.

As a result, the estimated ultimate recovery (EUR) from the Yumna Field has been revised upwards to 16.8 MMstb at the 2P level—an increase of 75 per cent compared with the original 9.6 MMstb estimate in 2020—effectively extending the productive life of the field through continued development, Rex International noted in its newly released 2025 Annual Report.

Singapore-headquartered Rex International, a multinational oil and gas exploration company, holds an effective indirect interest of 87.5 per cent in Masirah Oil Limited (MOL), which in turn holds 100 per cent of the Block 50 licence—a roughly 17,000 sq km offshore concession located in the Gulf of Masirah.

In 2025, hydrocarbon output from the Yumna Field declined to around 0.6 MMstb, compared with 0.864 MMstb recorded in 2024. As of December 31, 2025, the field had produced about 9.6 MMstb since July 2020, when the Ministry of Energy and Minerals granted a Declaration of Commerciality, paving the way for full-scale development of the offshore asset. Since then, five production wells have been drilled between 2020 and 2024, progressively supporting the field’s output.

Among other highlights in 2025, Masirah Oil installed a second flowline connecting the Mobile Offshore Production Unit (MOPU) to the Floating Storage and Offloading (FSO) unit to enhance system reliability, while the FSO was replaced to optimise cost efficiency.

Also during the year, MOL worked with energy consultant Gneiss Energy and various subsurface teams on a farm-out exercise for Block 50. “While no farm-out has resulted from the exercise, MOL gleaned important learnings and refined its future exploration and development plans for the block through deep technical engagement with potential partners,” Rex stated in its report.

Earlier this year, Rex Oman Ltd, MOL’s parent company, signed a contract for the Energy Emerger jack-up drilling rig, which will be used to drill three development wells in H1 2026 aimed at sustaining production. To help fund the programme, Jasmine Energy Ltd—of which MOL is an 87.5 per cent subsidiary—raised US$25 million in senior secured bonds with a three-year tenor.

In parallel, MOL plans to continue optimising production facilities and well operations, while also evaluating further exploration prospects within Block 50.