·       Deep-water deposystems and reservoirs of the Guyana-Suriname Basin: a synthesis (Professor Bryan Cronin, Tullow Oil)

This presentation builds on the structural compartmentalisation of the Guyana-Suriname offshore and charts the development of deposystems along the deep-water portion of the basin margin showing the source-to-sink arrangement of clastic systems from Late Cretaceous through to the Late Pliocene. Structural control on sediment pathways, the creation of accommodation space en route, and play configuration along a topographically irregular deep-water slope and basin floor, has set up a remarkable range of reservoir systems intricately associated with basin morphology. Intraslope transient fans and spectacular either levee confined constructional slope channel complexes or erosionally confined canyon plays with working stratigraphic or combination traps characterise the slope systems of Guyana and Suriname, whereas large scale frontal splay complexes with MTD-controlled stratigraphic or combination traps characterise the basin floor.

·       Regional reservoir character from legacy well database: Suriname-Guyana, with offset and conjugate margin analogues from Brazil and the Gulf of Guinea

(Dr Anne MacAfee, Corelab)

Extensive drilling during the past five years has proven the presence of prolific Late Cretaceous and Tertiary deep-water sandstone reservoirs in a well-established play fairway through eastern Guyana and western Suriname, but there are multiple additional exploration targets, particularly across the shelfal parts of this margin, which may also host significant reserves. Valuable information relating to these potential Cretaceous and Tertiary clastic and carbonate reservoirs has been extracted from the state archive and converted to fully digital formats to allow comparison with well datasets from adjoining and conjugate basins.  Although the vintage well data spans the full Jurassic to Tertiary succession, rock material is rather sparse at some levels and therefore interesting insights have been gained by comparing both reservoir and non-reservoir rock types in a ‘great regional’ context, including analogue Cretaceous and Tertiary Carbonates and Neocomian – Barremian clastics on the Equatorial Brazil Margin and Late Cretaceous shelf and slope sandstones on the West African Margin, where the inherited topography also played a role in deposition of siliceous mudstones.

·       Liza - the last giant oil play?

(Westwood Energy Group)

The Upper Cretaceous Liza play offshore Guyana and Suriname is the largest new oil play to emerge since the pre-salt Carbonate bonanza offshore Brazil, which started with Tupi in 2006 and has so far delivered ~30bnbbl of discovered resource. In the nine years between Tupi and Liza, more than 250 companies participated in over 350 frontier exploration wells globally, with ~70% of these targeting oil plays and more than half attempting to open new basins. 26 of these wells resulted in commercial discoveries, giving a 9% frontier commercial success rate. ~185 companies were left empty handed from their frontier exploration programmes. The Liza discovery appeared to be a game changer for frontier exploration. It opened a new oil play in what appeared to be primarily stratigraphic traps. In Guyana the Stabroek licence holders have reported a discovered resource of ~9bnboe, and in Suriname a further ~900mmbbl are estimated to have been discovered so far in Block 58. Attempts to extend the commercial limits of the play fairway have resulted in failures further outboard (Tanager 2020 and Bulletwood 2021), inboard (Carapa 2020) and to the east (Sloanea 2020). Apart from the Miocene discovery at Hammerhead, other plays tested, such as Mesozoic Carbonates (Ranger), Pliocene Clastics (Joe) and Oligocene Clastics (Jethro) all appear to be non-commercial at present.

The question may have turned from ‘When will the next Liza scale play be found?’ to ‘Will another Liza scale play be found?’ Any significant frontier play that is opened is likely to come from acreage that has already been awarded. There are a number of key frontier oil play tests expected in the next two years, but a historical success rate of less than 10% (and even less for oil plays) suggests that these are unlikely to be successful and even if they do work the follow on running room may be limited.

·       Carbonate Exploration Resource Plays – Guyana-Suriname Basin

(Stanley Rich Wharton - Subsurface Imaging Company Ltd)

Estimating Yet-to-Find resources in the Guyana-Suriname frontier Basin and depositional models are particularly challenging generally for Late Cretaceous carbonate play types on the Atlantic’s  Passive Margin.  While focus has been towards deep water turbidites, the successful discovery of Cretaceous carbonates in the Ranger exploratory well in Guyana, and the similar play type in the Walker exploratory well in Suriname, have provided excellent Key Wells for play assessment in the Basin. However, the presence of a shallow water shelf carbonate platform, penetrated by few wells together with an interpreted Cretaceous shelf edge, provides opportunity to explore the diversity of carbonate play types for hydrocarbon exploration. Albian to Turonian plays in particular, provide particular intrigue as  combined clastic/carbonate depositional systems and a challenge for applying regional analogues. This talk examines the current Late Cretaceous carbonate plays in the Basin along with potential regional analogs. Case example of an Albian to Turonian shelf margin play is also highlighted together with use of subsurface mapping technology