1. The Ellesmerian(!) petroleum system of the North Slope, Alaska, contains appr
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Question
1. The Ellesmerian(!) petroleum system of the North Slope, Alaska, contains approximately 77 billion bbl of oil equivalent. The cross section of the Ellesmerian(!) petroleum system (below) shows major structural-stratigraphic elements, the occurrence of oil fields, elevation of selected vitrinite reflectance values, and reflectance isograds. Nanushku Group, Sadlerochit and Endicott Groups are composed of sandstone 718) 9 INIGOK-1 coastine 0.6 - Nanushuk Group Post Cenomaniai rocks Torok Fm. and pebble shale unit, undivided Kingak Shale,... Sag River Ss, and Shublik Fm., Endicott Groups, aa Barrow Arch 6undivided Ikpikpuk Ro Values 0,25 Present-Day OifieldExplanation / Answer
The vitrinite reflectance is actually the quantification made for the measure of the extent of maturity present in a specific lithologic unit. So according to the maps given above the source rock of most probably the endicott sandstones which are of higher thermal maturity. The reservoirs are very much evident to be Nanushuk group of rock comprising of sandstones again. They can be reservoirs as they have a good yielding and permeable capability. The cap or seal rock is Undivided pebble shale unit. The definition of the the cap or seal rock says that it should be porous but not permeable. Hence the shale can serve as a purpose for that.
Most probably the kind of geological trap that we are talking about in this case is a structural trap. This is because there are oil fields projected above the cap rock which might suggest that it is an doubly folded trap.
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