BP and Kosmos Energy will assess the potential for a standalone liquefied natural gas development in the BirAllah area off Mauritania after their latest deep-water wildcat yielded the discovery of an estimated 13 trillion cubic feet of gas.

The UK supermajor and Dallas-based partner Kosmos struck 36 metres of net gas pay in the targeted Albian play at the Orca-1 well on Block C8, with operator BP saying the discovery was in line with pre-drill expectations but Kosmos saying it exceeded its own expectations.

“Operations are continuing and further work will be necessary to appraise the discovery and estimate resources,” BP said, although Kosmos ventured further, saying it believes the find is “the largest deep-water hydrocarbon discovery in the world so far this year”, yielding 13 Tcf of mean gas initially in place (GIIP).

Together with the nearby original Marsouin-1 discovery, which has been renamed BirAllah, Kosmos said the two wells “have de-risked up to 50 Tcf of GIIP from the Cenomanian and Albian plays in the BirAllah area”.

The well, drilled in 2510 metres of water to 5266 metres using the Valaris-owned drillship DS-12, also extended the Cenomanian play fairway by confirming 11 metres of net gas pay in a down-structure position relative to the original Marsouin-1 discovery well.

Kosmos said it believes the potential resources in the BirAllah area are now “more than sufficient… to support a world-class LNG project”.

The BirAllah area adds to discovered resources in the region for the partners, alongside Yakaar-Terenga off Senegal and the Greater Tortue-Ahmeyim area that straddles the maritime boundary between the two countries.

BP announced late last year that a final investment decision had been agreed on the first phase development of Tortue.

This week the supermajor said: “Together these (assets) further confirm our confidence that offshore Mauritania-Senegal is a world-class hydrocarbon basin with the potential for long-term gas development.”

Analysts at BMO Capital Markets said after the US independent first revealed the Orca find: “This was an important well for Kosmos that has gone a long way towards confirming a third hub in Mauritania and Senegal.”

Lennert Koch, principal analyst of sub-Sahara Africa upstream at UK-based Wood Mackenzie, said Orca provides BP and Kosmos with options on which resource to develop first.

“Each [option] is faced with a major monetisation challenge. Mauritania has no domestic gas market to speak of. There are plans to further develop Senegal’s gas market, but this will not be sufficient to develop these deep-water gas resources. The main way out will be liquefied natural gas,” Koch said.

“Developing another LNG project, and finding buyers for that LNG, could be challenging. Finding the right partners who can provide LNG offtake will be an important next step for the further developments after Tortue Phase 1.

“But if an onshore LNG solution can be found, BirAllah and Orca could prove to be a simpler hub than the cross-border Tortue development,” Koch added.

Jamie Collard, senior analyst at UK-based Westwood Global Energy Group, said: “The Orca discovery appears to open up development options for Marsouin, and a third LNG project for the MSGBC [Mauritania, Senegal, Gambia, Guinea-Bissau and Guinea-Conakry basin].

“Kosmos initially focused exploration in the MSGBC on the Upper Cretaceous plays. However, the recent success at Greater Tortue Ahmeyim-1, in June 2019, and now Orca has brought attention to the Lower Cretaceous, Albian section, with Kosmos now also considering potential in the deeper Aptian,” Collard added.

Palzor Shenga, a senior analyst at Norway-based Rystad Energy’s upstream team, estimated that Orca holds around 1.3 billion barrels of oil equivalent of recoverable resources.

“Mauritania and Senegal are slowly becoming world-class LNG centres, with three different planned hubs containing around 10 million tonnes per annum,” Shenga said of the Yakaar-Terenga, Tortue and BirAllah hubs.

Liam Kelleher, of WoodMac’s gas and LNG team, said: “We think the discoveries in Mauritania and Senegal will see the region become a major LNG hub in the long term, with a combined output of greater than 30 million tonnes per annum by the mid-2030s, pushing the region into the top 10 producers worldwide. Orca-1 simply adds to this potential.

“As the resource is right on Europe’s doorstep, it will be able to compete with expensive US LNG. Meanwhile, the majors are preparing for energy transition, in which gas will be a crucial ingredient,” he said.

BP operates Block C8 off Mauritania on 62%, with Kosmos on 28% and state player SMHPM on 10%.

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Orca success opens options for BP and Kosmos