--> --> Organic Geochemical and Organic Petrological Analysis of the Murray Harbour Formation: A Potential Unconventional Reservoir in the Sverdrup Basin, Canadian Arctic

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Organic Geochemical and Organic Petrological Analysis of the Murray Harbour Formation: A Potential Unconventional Reservoir in the Sverdrup Basin, Canadian Arctic

Abstract

Technological advances and increased energy demands will ultimately result in the development of unconventional hydrocarbon resources in the Canadian Arctic. The Murray Harbour Formation is a Middle Triassic, organic-rich marine mud and siltstone unit located in the Sverdrup Basin in the Canadian Arctic Archipelago. It has already been identified as one of the major source rocks for discovered conventional oil and gas fields in the basin. This study characterizes the dispersed organic matter within the Murray Harbour Formation to determine the unconventional hydrocarbon potential of the unit. Closely-spaced samples were collected from core from three wells drilled at variable depths within the Sverdrup Basin. Rock Eval 6 analysis results show median total organic carbon values ranging from 0 to 4.8 wt. %, with intervals from two of the wells showing values greater than 3 wt. %. Tmax values for samples from two of the wells indicate samples are within the oil generation window, and samples from the third well are at the beginning of the oil generation window. Organic petrologic examination of the cores reveals significant amounts of degraded and reworked vitrinite, inertinite and microfossil fragments. Due to the reworked nature of vitrinite, in-situ bitumen was utilized for reflectance measurements in order to determine thermal maturity of the unit. Some intervals show abundant fluorescing liptinitic algae and dispersed matrix bitumen, signifying remaining hydrocarbon generation potential. One core shows pore-filling bitumen with reflectance values that are higher than expected from corresponding Tmax values. This is suggestive of oxidation of organic matter and early-generated hydrocarbons through bacterial sulphate reduction. The range of observed reflectance values implies bacterial sulphate reduction occurred during sediment deposition as well as throughout burial. Differences in the character of organic matter between the three cores highlights the importance of determining which areas of the Murray Harbour Formation are likely to be most productive. Preliminary results suggest that certain zones in the formation may show good potential as unconventional hydrocarbon reservoirs.