Jamaica
Offshore / Exploration
Envoi has been engaged by London-listed (Dublin-based) United Oil & Gas Plc, to assist in their search for a partner to help accelerate the exploration of their large, 22,400 km2 100% operated Walton-Morant Block, located offshore southern Jamaica.
Only 11 wells have been drilled in the country to date; 9 onshore and just 2 offshore, all drilled between 1955 and 1983. None of these wells are now interpreted to have tested valid structures, although all contained hydrocarbon shows. Prior to United joining the licence, various vintages of pre-existing 2D seismic were combined and reprocessed, with 3,650 km of new 2D data acquired in 2016 and 2017. This helped further delineate and unlock the potential of the Walton Basin in the west and Morant Basin in the east of the acreage and led to the acquisition of 3D seismic over the Walton Basin ‘sweet spot’ in 2018.
Onshore fieldwork and well core analysis studies have confirmed Eocene and Cretaceous oil-prone source rock potential, with migrated hydrocarbons identified in onshore wells and outcrop samples as well as onshore and offshore seeps. These include Late Cretaceous (Cenomanian-Turonian) aged organic shales exhibiting TOCs up to 8% with maturity. Modelling suggests significant oil potential exists in mature Cretaceous source kitchens in both the Walton and Morant basins while shallower Palaeogene shales with TOCs up to 15% could also locally be deep enough to be mature.
The large Colibri Prospect is interpreted on 3D to contain karstified Upper Cretaceous carbonates developed on a prominent palaeo-horst. Additional, amplitude supported prospects have also been defined on the 3D in the Walton Basin, with Eocene-Oligocene carbonates as the primary reservoir targets. Eocene clastic reservoirs are the main reservoir target in the Morant Basin and include fluvio-deltaic and marine sandstones. These are found across onshore Jamaica in outcrop with depositional modelling indicating their distribution into the offshore. Eocene targets identified include a series of tilted fault block closures mapped on the 2D in the Morant Basin. Extensive shales, marls and tight limestones create effective seals across the two basins.
An independent Prospective Resources Audit completed by Gaffney Cline & Associates estimates that the 11 prospects & leads evaluated for the audit contain combined total unrisked mean prospective recoverable resources in excess of 2.4 Billion bbls. Of this, 406 MMbbls is attributable to the Colibri Prospect alone, with an upside of 966 MMbbls. Additional leads identified on older 2D seismic data could hold another 4.8 Billion bbls of mid-case unrisked prospective recoverable resources, indicating overall potential mean/mid-case unrisked prospective recoverable resources of more than 7 Billion bbls.
United has extended the current First Exploration Period of the licence for an additional 2 years to January 2028, in exchange for a modest technical work programme designed to further derisk the prospectivity identified. The work programme includes the acquisition of a piston coring survey (completed Q1 2026), together with seismic reprocessing to improve structural and reservoir imaging. United is looking for a partner, or partners, to join them in exploring this exciting and highly prospective licence ahead of entering the Second Exploration Period, which includes a drilling commitment, subject to a positive drill-or-drip decision being made at the end of the current licence period.
