--> Abstract: Seafloor Sampling Offshore Greenland and Jan Mayen for Stratigraphic Tie, Detection of Active Hydrocarbon Systems, and Conjugate Margin Geology, by Stephane Polteau; #90177 (2013)

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Seafloor Sampling Offshore Greenland and Jan Mayen for Stratigraphic Tie, Detection of Active Hydrocarbon Systems, and Conjugate Margin Geology

Stephane Polteau

Some of the last frontier areas for oil and gas exploration with a large potential of hydrocarbon accumulations are located in the Arctic where very little geological information is available due to rough weather and heavy sea-ice conditions. Without well control, the geological understanding in these challenging regions relies on correlating onshore geology to offshore seismic reflections, and on assuming a geological continuity between conjugate margins. Between 2008 and 2012, VBPR and TGS surveyed several frontier basins around Greenland (Baffin Bay, Fylla, Ammassalik, and Northeast Greenland shelf) and the southern Jan Mayen Ridge. The main aim of these cruises was to sample subcropping strata interpreted from seismic refection data in order to establish a geological tie to the truncated reflections on the seafloor. The seabed was sampled using gravity cores for point samples and dredges along steep escarpments for collection of a wider variety of near in-situ rocks that would otherwise not be sampled by gravity coring. The gravity core samples that are identified as subcrops are used to construct a pseudo-well, and the results provide a direct geology-seismic tie. Dredge samples complement the gravity cores and fill the gaps between sampling stations. Collected sediment samples are dated using biostratigraphy, and further analyzed for source and reservoir rock properties. Biostratigraphy results show that gravity core samples in almost all cases are in the correct age sequence in relation to the sampled localities. The results are summarized in a lithostratigraphic log providing information about depositional environments, reservoir rock quality, and maturation of source rocks. The secondary aim of these cruises is to identify the presence of active petroleum system by targeting potential seepage sites (shallow amplitude anomalies, depressions on the seafloor, terminations of deep-seated faults, and salt diapirs). The lowermost part of the recovered material from gravity coring is analyzed for headspace gas, GCMS, and biomarkers. Our results are the first to show the presence of live-oil in Baffin Bay, NE Greenland, and in the southern Jan Mayen Ridge, and further indicate Jurassic and Cretaceous sources with maturities in the main- to post-oil windows. Finally, this robust sampling approach, when applied during early exploration phases in any frontier region, provides results that can be integrated in basin models to increase confidence in selecting exploration targets and reducing exploration risks.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013