--> 2D and 3D Seismic Delineation of Submarine Fan Systems in the Guyana/Suriname Basin.

AAPG Pacific Section Convention, 2020 Vision: Producing the Future:

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2D and 3D Seismic Delineation of Submarine Fan Systems in the Guyana/Suriname Basin.

Abstract

Oil discoveries since 2015 in the offshore Guyana/Suriname basin total over 6 billion barrels recoverable. The primary reservoir, turbidite sandstones, should seem very familiar from similar deposits (and outcrops) in California. The focus here is on the submarine canyons, incised upper fan channels and mid-fan features. 2D seismic surveys are sufficient to map the general thickness and extent of entire fan systems. Most of the recent discoveries have been in the Late Cretaceous section, where there is one major canyon supplying sediment, Berbice. An additional turbidite system, Early Tertiary in age, is associated with several canyons, none as large as Berbice. 3D seismic provides much better imaging and all of the recent wells have been located with 3D surveys to identify potential stratigraphic traps. Seismic amplitude displays in map view illustrate the geometry of incised upper fan channels and the transition to the less laterally confined mid-fan. The discoveries in the Late Cretaceous have been made past the incised upper fan channels in the mid-fan setting. Earlier, unsuccessful, wells were more proximal. There are also recent oil discoveries in the Early Tertiary section, in a similar depositional setting. In the 1970’s the offshore 2D seismic surveys were used to identify potential structural closures and drilling was restricted to fairly shallow water. Earlier in the 60’s, oil discoveries were made along the coast which proved the basin had an active petroleum system. No one could find the right place to drill offshore. As deepwater drilling became more common world-wide, the international marine boundary was disputed and this delayed exploration in the basin. The first well clearly targeting turbidite sands in a stratigraphic trap was in 2008 in Suriname. It was not a discovery. There was a discovery well in nearby French Guiana that provided encouragement, and then the first really significant offshore discovery in the basin was made in 2015 in Guyana (Esso Liza-1). There have been over fifteen discovery wells drilled (most by the Esso group). A significant part of the basin lies offshore Suriname. Few wells have been drilled for turbidite sands, but one discovery was recently announced (Apache Maka Central-1).