The Darwin Discovery and Its Implication on the Hydrocarbon Potential of the South Falkland Basin

Abstract

Abstract

Three wells have been drilled in the South Falkland Basin (SFB) resulting in one discovery, Darwin. The wells have provided valuable stratigraphic information and have constrained the hydrocarbon potential of the basin.

The SFB is located along the southern margin of the South American plate. During the late Jurassic/Early Cretaceous the basin evolved as a passive margin along the northern margin of the opening Weddell Sea. During the Cenozoic differential movements between the South American plate (SAP) and Antarctica resulted in loading of the southern margin of the SAP creating a foreland fold and thrust belt.

The Darwin well, drilled in 2012, targeted an Early Cretaceous shelf sandstone in a robust tilted fault block structure. The prospect was defined by amplitude conformance to structure and a class 3 AVO response. The well penetrated a rich gas condensate (148 to 152 bo/MMcfg) with a gross hydrocarbon ‘down-to’ interval of 84.5m. The high quality reservoir encountered provides a strong seismic contrast when comparing reservoir fluid types, helping to highlight prosectivity away from the well location. Post well analysis indicates the best un-risked estimate (P50), incorporating all proven and potential reservoirs, is 360 million barrels of recoverable condensate (3.49 Tcf WGIIP).

Darwin has confirmed the regional extent of the Late Jurassic to Early Cretaceous source rock demonstrating both oil and gas charge potential. Shallow marine sands, deposited along the Early Cretaceous passive margin shelf, have provided multiple target horizons. The provenance for the sands is the paleo-Falklands landmass, located to the north of the well location. Off the shelf, deep water channels and fans of similar age provide additional targets. Tectonics associated with Jurassic rifting and the Tertiary fold and thrust belt provide a variety of structural traps, including tilted fault blocks, large broad thrust cored anticlines and combination structural / stratigraphic traps.

Post well studies have provided fresh insights into the hydrocarbon potential of this frontier province. Excellent reservoir properties have enabled the application of seismic inversion to further explore the elastic response and enhance the prospectivity of the basin. Given the extent of the basin and the presence of the key play elements the Darwin discovery is likely to be a foundation stone that is built upon in this emerging fairway.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016