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Oil to Source Rock Correlation in Western Newfoundland
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- Author / Creator
- Schwangler, Martin
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The presence of natural oil seeps, abandoned well sites (generally containing light oil), and high quality source rocks along the coast of western Newfoundland has refocused interest on the region as an area for potential petroleum exploration and development. Most of the oil seeps and old well sites are located in the Cow Head and Port au Port Peninsula areas. These areas lie in the Humber Zone, located on the eastern margin of the Anticosti Basin - the structural front of the northeastern Canadian Appalachians. The current study aims to characterize source rocks and oils in this active petroleum system. The geologic history of the area is complex, and has important implications for the petroleum system. Neoproterozoic continental breakup was followed by the development of a passive continental margin containing coeval shelf carbonates and continental slope and rise deposits of the Humber Arm Allochthon. During the Taconian (Ordovician) and Acadian (Devonian) orogenies, westward thrusting imbricated continental slope and rise deposits, creating thrust sheets that repeat Lower Paleozoic strata. This underlying geology created an active petroleum system with potential reservoirs in the overridden platform carbonates, which are time-equivalent to slope deposits of the Cow Head Group, containing source rocks. Other potential reservoirs can be found in shelf proximal carbonate conglomerates associated with debris flows. The connection between the identified source rocks and produced hydrocarbons is not well understood. In the present analysis, I show that high-quality source rocks were deposited during two distinct periods: the Cambrian Series 3 to Furongian Series, and the Ordovician Floian stage. These late Cambrian to early Ordovician deep marine gravity flow deposits contain viable type I/ II and type II/III source rocks. Total organic carbon (TOC) concentrations of up to 9.45 wt% and hydrogen index values as high as 841 [mg HC/g TOC] demarcate the Middle Arm Point Formation of the Cow Head Group. Detailed biomarker and isotope analysis of source rock extracts show a statistically significant change in source dependent biomarker composition from the Cambrian to the Ordovician, identifying both bacterially (Cambrian) and algal (Ordovician) derived organic matter. The same change in biomarker composition can be identified in bitumen and oil samples, linking the source intervals to two endmember petroleum groups. Analysis of thermal maturity-sensitive biomarkers reflect the complex tectonic history of western Newfoundland. In the Cow Head area both source rocks generate oil with a wide ranging of maturities (0.7 to 1.11 %Ro equivalent), related to the dipping character of the imbricated thrust stacks containing source rocks. The Port au Port No.1 well was charged by the Cambrian source rock and then underwent secondary cracking, indicated by concentrations of 3 + 4-methyldiamantane. Low maturity natural seeps from Port au Port Bay can be related to the Middle Ordovician Middle Arm Point Formation. Biomarker and carbon isotope data were successfully used to correlate oil to source rocks in western Newfoundland and are a valuable tool to resolve thermal and generation history of oils in tectonically complex petroleum basins.
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- Subjects / Keywords
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- Graduation date
- Spring 2018
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.