Hess Corp. is boosting working interest offshore Guyana through a recent farm-in northeast of the massive Stabroek Block in the Guyana-Suriname Basin.

The increase was made via a farm down by Cataleya Energy Ltd. of a 5% working interest in the Kaieteur Block offshore Guyana, increasing Hess’ interest to 20% from 15%, according to a note from Westmount Energy Ltd. published May 24. Westmount holds shares in Cataleya Energy and Ratio Petroleum Energy LP, both partners of the Kaieteur JV.

Gerard Walsh, executive chairman of Westmount Energy, believes the farm-in transaction with Hess reflects confidence in the prospective resource potential of the Kaieteur Block and bodes well for the continuing exploration of the area despite disappointing results from Tanager-1, the first well drilled on the block.

“We are very encouraged to see Hess, one of the Stabroek Block partners and a leading player in the Guyana-Suriname Basin, increase its WI (working interest) in the Kaieteur Block on the back of the 2020 Tanager-1 oil discovery,” Walsh said in a statement.

Exxon Mobil Corp., operator of the Kaieteur Block,  also leads the oil exploration campaign for Stabroek with partners Hess and CNOOC Ltd. To date, the group have made 19 discoveries totaling some 9 billion barrels of recoverable oil and gas, including the Uaru-2 well announced in April.

On the neighboring Kaieteur Block, Exxon Mobil reported the Tanager-1 well as an oil discovery last November. However, Tanager-1 is currently considered to be non-commercial as a standalone development, according to the Westmount note.

The Kaieteur JV partners are currently high grading the next potential drilling targets based on recent 3D seismic data indicating a substantial Cretaceous prospect inventory in the southern part of the block, the note added.

Tanager-1 encountered 16 m of net oil pay in high-quality sandstone reservoirs of Maastrichtian age and confirmed the extension of the Cretaceous petroleum system and the Liza play fairway outboard from the prolific discoveries on the neighboring operated Stabroek Block. High quality reservoirs were also encountered in Tanager-1 at the deeper Santonian and Turonian intervals though interpretation of the reservoir fluids was reported to be equivocal and require further analysis.

“This move is consistent with the Stabroek partners’ assessment that the total basin potential of the Guyana-Suriname Basin is now more than twice the discovered resource to date—indicating a potential yet-to-find resource in excess of 10 billion oil-equivalent barrels across the basin,” Walsh added in his statement on the farm-in transaction with Hess.

“It is also consistent with the view that considerable hydrocarbon resource potential may be present in the newly emerging deeper plays, such as the Lower Campanian/Upper Santonian play, where the 3D seismic data suggests that the channel systems are at least as extensive in area as they are in the shallower Maastrichtian/Upper Campanian Liza play fairway,” he continued.

Post the farm-in transaction, Hess holds 20% working interest in the Kaieteur JV. Exxon Mobil affiliate Esso Exploration and Production Guyana Ltd. remains operator with a 35% stake in the project. The remaining interest is held by Ratio Guyana Ltd. and Cataleya Energy, 25% and 20%, respectively.