Impact of Long- and Short-Term Geodynamic Processes on Hydrocarbon Reservoirs in the Grand Banks

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MacDougall, Malcolm
Geophysics , Geodynamics , Numerical Modelling , Seismic Interpretation , Gravity , Glacial Isostatic Adjustment , Petroleum , Grand Banks
The evolution of the passive margin off the coast of Eastern Canada has been characterized by a series of rifting episodes beginning approximately 200 ma which caused widespread extension of the lithosphere and associated structural anomalies, some with the potential to be classified as a result of lithospheric boudinage. Crustal thinning of competent layers is often apparent in seismic sections, and deeper Moho undulations may appear as repeating elongated anomalies in gravity and magnetic surveys. This investigation supplements our knowledge of analogous examples which have been linked to boudinage as a driving mechanism, to determine that similar structures are evident in the context of the Grand Banks. More recently in the last 20 ka, the region has been subject to crustal warping and Glacial Isostatic Adjustment (GIA)-induced visco-elastic deformation. Numerical simulations were run using different rheological parameters and ice load histories to obtain a model which may be representative of the isostatic response for the Grand Banks. The goal was to assess the potential impact on hydrocarbon reservoirs and trapping structures as a consequence of GIA processes, which may include various deformation-related implications.. Comparisons may be drawn to related studies, including the postglacial implications on reservoirs in the Barents Sea, as well as validation of GIA model predictions using GPS and Canadian Base Network vertical motion data to determine a best-fitting model to the present-day observations. As a result of this study, it is clear that there are potential effects from GIA since the Last Glacial Maximum, and there is still vertical motion in the region meaning these effects may continue.
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