Reservoir potential of sands formed in glaciomarine environments: an analogue study based on Cenozoic examples from McMurdo Sound, Antarctica
Published:January 01, 2012
Christopher R. Fielding, Brian A. Blackstone, Tracy D. Frank, Zi Gui, 2012. "Reservoir potential of sands formed in glaciomarine environments: an analogue study based on Cenozoic examples from McMurdo Sound, Antarctica", Glaciogenic Reservoirs and Hydrocarbon Systems, M. Huuse, J. Redfern, D. P. Le Heron, R. J. Dixon, A. Moscariello, J. Craig
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This paper provides documentation of unexpectedly high-reservoir-quality glaciomarine sands found in the Cenozoic succession beneath McMurdo Sound, Antarctica, as an analogue study for evaluations of hydrocarbon prospectivity in basins elsewhere. The Oligocene to Lower Miocene succession of the Victoria Land Basin, an extant portion of the West Antarctic Rift System, comprises diamictites, mudrocks and sandstones with minor conglomerates. These lithologies are arranged in repetitive stacking patterns (cycles), interpreted to record repeated advance and retreat of glaciers into and out of the basin, with attendant eustatic and isostatic effects. Phases of ice retreat within the cycles comprise an array of mudrocks, sandy mudrocks and sandstones, deposited mainly during relative sea-level highstands. Clean, well-sorted, unconsolidated and porous sands <25 m thick from such intervals, which are interpreted to be mainly deltaic in origin, were encountered. Some of these sands, which have visible porosity as high as 41%, flowed into the well bore together with significant volumes of cold formation water. Diagenetic modification of sands in these intervals is minimal, which can be attributed to the low-temperature nature of the subsurface environment. Accordingly, glaciomarine sands in near-field glaciogenic successions should be considered as potential reservoir facies in prospectivity assessments.
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Glaciogenic Reservoirs and Hydrocarbon Systems
Glaciogenic reservoirs and hydrocarbon systems occur intermittently throughout the stratigraphic record, with particular prominence in Neoproterozoic, Late Ordovician, Permo-Carboniferous and Late Cenozoic strata. Recent interest in glaciogenic successions has been fuelled by hydrocarbon discoveries in ancient glaciogenic reservoirs in North Africa, the Middle East, Australia and South America. Glaciogenic deposits of Pleistocene age are noteworthy for their content of groundwater onshore and potentially prospective and/or hazardous gas accumulations offshore. The abundant imprints of Pleistocene glaciations in both hemispheres can be used to reconstruct complex histories of repeated ice cover and retreat, and glacier-bed interactions, thus informing our view on the dynamics of older ice caps and predictions of future glaciations. This volume aims to provide a better understanding of glaciogenic processes, their stratigraphic record and reservoir characteristics of glaciogenic deposits. The book comprises 3 overview papers and 16 original case studies of Neoproterozoic to Pleistocene successions on 6 continents and will be of interest to sedimentologists, glaciologists, geophysicists, hydrologists and petroleum geologists alike.