Stratigraphy, Paleogeography and Related Reservoir Potential of Pennsylvanian-Permian Mixed Carbonate-Siliciclastics, Sverdrup Basin, Canadian Arctic
On southwestern Ellesmere Island, along the southern margin of the Sverdrup Basin, Pennsylvanian to Permian strata captures a unique snapshot in time where nearshore siliciclastics interfinger with inner shelf carbonates. These carbonate and siliciclastic cycles, or cyclothems, are primarily a result of glacial eustatic fluctuations from the southern ice sheet located on Gondwanaland, which create a unique depositional environment and stratigraphic relationships. These cyclothems are of great interest, as they can yield good reservoirs as a result of porous units being pinched out by impermeable strata brought on by transgressive cycles.
The mixed carbonate-siliciclastic cyclothems exposed in the Blind Fiord area of Ellesmere Island, exhibit porosity development that is attributed to meteoric diagenesis and subaerial exposure. Due to the complexity associated with mixed carbonate-siliciclastic systems, deciphering the paleogeography of such environments and mapping stratigraphic sequences was a key objective of this study. To further understand the extent of the porosity development and possible associated reservoir potential, detailed assessment of these cycles through sedimentology, stratigraphy, petrography and micro-paleontology has been conducted in both the field and laboratory. To further aid in assessing the extent and timing of porosity-occluding processes, carbon and oxygen isotope changes associated with subaerial exposure and diagenetic processes have been documented.
The Sverdrup Basin is rich in natural resources. This study provides insight on the glacial-eustatic cyclicity correlating to the mixed carbonate-siliciclastic Upper Paleozoic setting along the southern margin of the Sverdrup Basin, as well it provides a understanding of porosity enhancement in such a setting. Furthermore, this study has revealed the presence of bitumen along thoroughly mixed carbonate-siliciclastic strata, which are often the most porous units. Currently, additional work is being completed to assess the extent of this possible hydrocarbon potential, as well as where the origin of this potential may be. With increasing interest and importance of Arctic exploration this study will provide invaluable insight on the Upper Paleozoic mixed cyclothems of the Sverdrup Basin.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California