Walton-Morant Licence, offshore Jamaica (Colibri)
In November 2017, United Oil & Gas farmed into the Tullow Oil operated Walton Morant Licence, offshore Jamaica, at a 20% equity level.
In May 2018, the acquisition of 2,250km2 of 3D seismic data was successfully completed. This was the first ever 3D survey completed in Jamaica and was focussed on the high-graded Colibri Prospect.
In July 2020 United received approval from the Jamaican Government to take the Walton Morant Licence forward on a 100% operated basis, with Tullow’s 80% equity transferred to United for a nominal fee. The amended Walton Morant Licence covers an area of c. 22,400km2.
United has been granted an 18-month extension to the Initial Exploration Period of the licence and has until the 31st January 2022 before a drill-or-drop decision is required, prior to entry into the Second Exploration Period and a commitment to the drilling of an exploration well.
During the 18-month extension, United will complete an agreed work programme aimed at further de-risking the prospectivity on the block. In December 2020, a prospective resources report by Gaffney Cline & Associates estimated unrisked mean prospective recoverable resources >2.4 Bstb of across 11 high graded prospects & leads in the Walton Morant Licence area.
Walton Morant Licence, offshore Jamaica
About the Walton Morant Licence
Although offshore Jamaica is a true Frontier Basin, there is compelling evidence that a working petroleum system is present.
11 wells have been drilled in Jamaica to date (9 onshore, 2 offshore). None of these wells are considered to have tested valid structures, yet all bar one contained hydrocarbon shows. The most recent of these wells was drilled in 1983.
Extensive fieldwork, drop-core and seep analysis studies were conducted between 2014 and 2017, prior to United joining the licence. 3,650km of 2D seismic were also acquired in 2016 and 2017. This work served to increase the confidence in the presence of a working petroleum system, high-graded the preferred plays, and led to the identification of numerous structures, including the robust Colibri Prospect which is in an optimal location to test the offshore Jamaica petroleum system.
Since United farmed into the licence, significant additional seismic survey work has been carried out, including the acquisition and interpretation of 2,250km2 of 3D seismic data around the Colibri Prospect in 2018.
This new data and interpretation formed the basis of an independent Prospective Resources Audit (Gaffney Cline & Associates, December 2020), commissioned by United, which attributes a total gross un-risked mean prospective recoverable resource of 406 MMstb to the Colibri Prospect. In the high case, Colibri could hold a gross unrisked prospective recoverable resource of 966 MMstb.
The Walton Morant Licence covers an extensive area (c. 22,400km2) and contains numerous follow-up structures which would be significantly de-risked by future drilling success at Colibri.
Identified prospects and leads, Walton Morant Licence, offshore Jamaica
Walton Morant Play Elements and Stratigraphy
- Oil-prone source rocks have been identified in the Eocene and in the Cretaceous, with migrant oil identified in onshore wells and outcrop samples.
- Two positive offshore seep surveys have been recorded, including on the active Blower Rock seep to the south of Colibri. This provides good evidence of the presence of regional source rocks.
Maturity and Migration
- Extensive maturity modelling suggests significant oil would have been expelled from Eocene kitchens in both the Walton and Morant basins.
- Colibri is considered to be optimally positioned to test for hydrocarbon migration from an identified Eocene kitchen and, if successful, would significantly de-risk the follow-on prospectivity on the Licence.
- On the Caribbean Plate, reservoir has often been cited as an issue due to the distance from major continental clastic input and the high proportion of volcanics in the region, which tend to downgrade reservoir quality.
- There is, however, good evidence from field-mapping and from plate reconstructions that during the Eocene, Jamaica was receiving sediment from the continental Maya-Chortis block. For example, the Eocene Guys Hill Formation, a fluvio-deltaic to shallow marine clastic succession is evident across much of onshore Jamaica. Similar sediments were found in the offshore Arawak-1 well and depositional models suggest these sediments should be distributed across the Walton and Morant basins.
- There are also abundant carbonates within the Walton Morant Licence as evident from the presence of the large Pedro Bank to the southwest of the block. Carbonates are considered to be present from at least the Cretaceous and are expected to form viable reservoir targets.
- Numerous examples of shales, marls and tight limestones are evident onshore in outcrop as well as in the wells drilled to date.
- These are expected to be present offshore also, with regionally significant shales and marls deposited during the Eocene.
- A number of structural and stratigraphic traps have been identified in both the Walton and Morant Basins, including horst structures (Colibri), tilted fault blocks (Moonraker) and stratigraphic pinch-outs (Oriole).