The prospective resource estimate for the Tullow Oil-operated Orinduik block off Guyana has been boosted by around 37% in a new third-party assessment to nearly 4 billion barrels of oil equivalent as the UK operator prepares to spud an initial wildcat on the tract.

The best-case estimate for gross prospective resources has now been upgraded to 3.982 billion boe on a proven-and-probable (P50) basis, compared with a previous figure of 2.913 billion boe, in the latest competent person’s report prepared by Gustavson Associates for block partner Eco Atlantic Oil & Gas.

The firm has also firmed up a pre-drill P50 resource estimate of 214.5 million boe for the Jethro-Lobe prospect - down from an initial target of 250 million boe - in the block that is set to be drilled in June this year using drillship Stena Forth.

The Stena Drilling-owned unit was contracted earlier this year at a dayrate of around $170,000 for the estimated 74-day drilling effort, according to Bassoe Analytics.

The revised resource figure, of which 597.3 million boe is net to Eco, is based on 15 exploration leads identified on the 1800 square-kilometre block that is located in the shallow-water Suriname-Guayana basin, adjacent to ExxonMobil’s prolific Stabroek tract where the US supermajor recently upped the resource estimate to 5.5 billion boe after making its 12th discovery in the block.

It follows processing and interpretation of fresh 3D seismic acquired in an extensive 2550 square-kilometre survey at Orinduik carried out in 2017 by Western Geophysical.

Eco’s chief operating officer Colin Kinley said analysis of ExxonMobil’s Hammerhead-1 discovery and other Tertiary-aged finds in the Stabroek block had “confirmed the presence of oil” at Orinduik.

He added that Hammerhead “will be offset drilled on the Stabroek block in the near future, which will help further define our interpretation of our other leads and targets”.

Kinley said that, while the revised volume estimate for Jethro-Lobe was “conservative”, there was a low risk for drilling with an 81% chance of success and the block partners are looking to drill further “strategic lower risk targets”.

The best estimate for in-place oil resources at Orinduik has now been put at 12.98 billion barrels, up from a previous prognosis of 3.483 billion barrels, with 3.5 billion barrels of prospective oil resources and 2.84 billion cubic feet of prospective gas resources, up from 942 million barrels and 921 Bcf, respectively.

Tullow, which holds a 60% operating stake in the block, together with partners Total (25%) and Eco (15%) are now in the process of approving a second exploration well at Orinduik.

“We hope to confirm drilling plans for well number two in the near future to take advantage of the economics of our rig on the block,” Kinley said.

Exploration

Resource boost at Orinduik