Yumna 1 well was tested at a production rate of 11,843stb/d through a one-inch choke. Credit: Malyszkz.
Oil produced at the field is exported through ship-to-ship transfers. Credit: FreeImages.com / athewma athewma.

Yumna oil field located in Block 50 Oman at a water depth of 30m, approximately 30km offshore east Oman, is being developed by Masirah Oil.

Masirah Oil, a subsidiary of Rex International Holding, holds 100% interest in the Block 50 Oman. Rex holds an 86.37% stake in Masirah Oil.

The approval of the field development plan (FDP) for the oil field from Oman’s Ministry of Oil and Gas and a declaration of commerciality (DOC) were secured in July 2020. The DOC allows Masirah Oil to undertake full-scale development of Yumna oil field and continue exploration in the remaining block licence.

Yumna field is estimated to hold proven reserves of 9.6 million stock tank barrels (Mmstb) as of July 2020.

Block 50 Oman details

Block 50 Oman is an offshore concession, covering an area of approximately 17,000km² in Gulf of Masirah, east of Oman. Masirah Oil acquired the concession in February 2011.

"Yumna field is estimated to hold proven reserves of 9.6 million stock tank barrels (Mmstb) as of July 2020."

Two exploration wells were drilled in Block 50 in a two-well drilling programme in 2013. The second exploratory well confirmed the presence of oil in the Yumna discovery (previously known as GA South) in February 2014.

Marine geophysical services provider Dolphin Geophysical began 3D seismic survey of the concession, using Artemis Arctic vessel, in November 2014.

Yumna oil field discovery details

The first offshore discovery in the east of Oman, the Yumna discovery was made following exploration activity for approximately three decades in the area. Oil was encountered in the Upper Sandstone member of the Campanian, Lower Aruma Sandstone Formation.

A flow rate of 3,500 stock tank barrels a day (stb/d) of light oil was achieved during testing of the discovery.

Yumna field appraisal details

Yumna 1 appraisal well was drilled by Foresight Driller IX jack-up rig in Block 50 Oman in December 2019 that confirmed the reservoir model in the block.

It was tested at a production rate of 11,843stb/d through a one-inch choke with 42° API crude oil gravity.

First oil flow from Yumna 1 was achieved successfully in February 2020. The oil flowed into the Mt Bull Papua Aframax tanker, which has a storage capacity of more than 750,000 barrels. The crude oil produced during the appraisal phase is stored in floating storage and offloading (FSO) vessel moored 500m away via a flexible flowline. In addition, the stored oil is exported through ship-to-ship transfers.

The well currently produces more than 8,000 barrels of oil a day through a one-inch choke with 440 pounds per square inch gauge (psig) flowing tubing-head pressure. It produced more than one million barrels of oil to date.

Yumna oil field development details

Two production wells and an exploration well will be drilled in Block 50 Oman, using the Tenacious jack-up rig.

Yumna 2 production well and the third production well will add to the existing permanent production facilities of Yumna 1 to improve the productivity of Yumna field and maximise recovery.

The wildcat exploratory well with the estimated gross unrisked prospective resources of 152.3Mmstb will be drilled in 2021.

Financing details

Masirah raised $21.5m in an investment round to fund the Yumna oil field’s appraisal well drilling in January 2020.

Contractors involved

Foresight Offshore Drilling was contracted to provide the jack-up rig to drill an appraisal well, while Wings Offshore received the contract to supply an FSO vessel to store crude oil in November 2019.

Shelf Drilling was awarded a contract to provide Tenacious jack-up rig to drill the production and exploration wells in November 2020.

Other developments in Block 50 Oman

The drilling of the Manarah-1 exploration well began in Block 50 Oman in February 2016. The well was drilled to a depth of more than 3,000m to explore multiple target zones in the basin.

Karamah-1 exploration well was drilled to a total depth of 3,320m, using the cantilever jack-up rig Aban VII, in March 2017. Both the wells were drilled at a water depth of 23m, which confirmed the presence of a working petroleum system in the block.