GWL Cluster Meeting
Thursday, 20th March 2014; 6:00 for 6:30 pm at the RCA, Crown Lane, Conwy
Geology and petroleum systems of the Falkland Islands Basins
Speaker Profile:
Colin More is Technical Director at Falkland Oil and Gas Limited (FOGL), a company solely focused on exploration offshore the Falklands. He is a geologist by training (BSc Glasgow, 1982; MSc Aberdeen, 1983) who, after a brief flirtation with geochemistry (1984), moved into geophysics and then exploration management. He worked for Conoco, Cairn Energy and Paladin in various exploration and appraisal roles, before joining FOGL in early 2006. His experience takes in numerous basins types worldwide, from intra-cratonic rifts in Sudan, China, India, UK and Thailand to thrust belts in Turkey and passive margins in NW Europe, West Africa and South Asia. He relishes the opportunity to take a frontier basin from first commercial seismic survey, through first well, to one day (maybe), first oil in the East Falklands Basin.
Abstract:
The basins offshore the Falkland Islands can be divided into two groups. The South and East Falklands Basins were formed during early break up of Gondwana, as Antarctica separated from the ‘African’ continent. The South and East Falklands Basins then developed as passive margins from the Middle Jurassic, initially to the Weddell Sea but subsequently, after final separation of South America from South Africa, to the South Atlantic. The North Falklands (NFB) Basin in contrast formed in the Late Jurassic to Early Cretaceous as a continental rift associated with the opening of the South Atlantic.
The fill of the East Falkland Basin is thought to be entirely marine. The first wells in the basin were drilled as part of the ODP/DSDP programme on Maurice Ewing Bank on the eastern tip of the South American plate. These wells revealed the presence of rich, upper Jurassic and Lower Cretaceous marine source rocks. Acreage in the basin was first licensed in 2002, the first seismic was acquired in 2004 and the first commercial well was drilled in 2010. This well (Toroa-1) demonstrated the presence of thick, good quality, Lower Cretaceous, shelfal sandstones derived from Palaeozoic quartzitic sediments which are preserved on the Falkland Islands. This set up the main play currently being targeted in the basin: Lower Cretaceous deep marine, slope channels and basin floor fans, sitting within and above the Lower Cretaceous source rocks, proven in the DSDP wells and in the offset Magallanes basin in Argentina.
The first wells were drilling in the NFB in 1998 and although no commercial discoveries were made the key elements of a working hydrocarbon system were proven. The basin is predominantly filled with lacustrine and fluvial sediments with fully marine conditions only established in the Tertiary. The primary source rocks in the NFB are Lower Cretaceous (Barremian to Valanginian) lacustrine, oil-prone, algal shales deposited within the early post-rift sequence. These extraordinarily rich source rocks are mature for oil generation below 2500m but it is the juxtaposition of source and reservoir that could make the NFB a prolific province. Lacustrine reservoirs, shed as fans from a fringing shelf on the eastern basin margin and inter-bedded with the mature source rocks, are the current focus of exploration. The billion barrel (STOIIP) Sea Lion field, discovered by Rockhopper Exploration in 2010, is testament to the effectiveness of the play.
This talk will focus on the East Falklands Basin where the Noble Energy, Edison SPA and Falkland Oil and Gas joint venture has recently acquired over 10,000sqkm of 3D seismic. However, the basin and plays will be compared and contrasted with the coeval NFB. The 2012 drilling campaign (South and East Falklands Basins) demonstrated the presence of a working petroleum system. The Scotia (FOGL), Loligo (FOGL) and Stebbing (Borders and Southern) wells contained gas and the Darwin well (Borders and Southern) discovered a very rich, gas condensate. The current play focus may be the Lower Cretaceous deep water systems but numerous other plays have barley been tested; like the Tertiary anticlines in the southern fold belt (Scotia Sea margin) and classic titled fault blocks in Upper Jurassic and Lower Cretaceous shelfal sands.
In frontier exploration, understanding the early basin evolution can be as important to success as prospect mapping on modern 3D. Plate models, play models and prospect examples will be presented to illustrate what could become a major new petroleum province in the South Atlantic.