Sea Floor 65 million years ago (Courtesy of Mark Deptuck) larger image [JPEG, 47.0 kb, 440 X 330, notice]

(Courtesy of Veritas DGC.) larger image [JPEG, 126.3 kb, 440 X 295, notice]

In 2002, 30% of Canada's conventional light crude oil production was from the Jeanne d'Arc Basin, offshore Newfoundland. The Lesser Known Basins project is stimulating exploration interest in other basins off the Newfoundland coast. One exciting development is the use of new software to model the location of source rocks, migration paths and potential reservoirs of oil and natural gas. (PAS project)

Petroleum Systems of Lesser Known Basins of the Grand Banks

Rationale

The Grand Banks region of offshore eastern Newfoundland contains several sedimentary Basins. These basins have been the target of sporadic petroleum exploration since the early 1960's, with the first well spudded in the 1966. Successes in the Jeanne d'Arc Basin (1979 Hibernia discovery, 1981 Hebron, 1982 Ben Nevis, 1984 Terra Nova, 1984 White Rose) curtailed exploration activity in these other, lesser known basins. There were hydrocarbon shows in several of these basins. The geological understanding of what underlies these petroleum systems remains incomplete.

Approach

To address this gap, this project reviewed the available well and seismic data with new biostratigraphic, geochemical, fission track and fluid inclusion information, with a focus on the Carson Basin. The results have a strong bearing on the petroleum potential of the neighbouring Salar Basin, about which very little is known.

Outline of basins, well locations on tectonic elements background. larger image [JPEG, 303.6 kb, 800 X 830, notice]

To understand what goes on in an evolving petroleum system, these data were entered into a basin model to simulate such a system. The geo-data constrained model was simulated with a range of variables to address tectonic influences and heat flow regimes.

Geology

Assuming a Jurassic potential source rock (based on revised geological interpretations) and using paleo-heat flow values that take rifting into account, the model shows that significant volumes of hydrocarbons were generated, migrated and stored, primarily in stratigraphic traps. The main risk from an exploratory viewpoint is the timing of trap formation versus hydrocarbon generation; this is a major concern due to the pervasive salt movement and is likely a major reason for the disappointing exploration results.

The results from the basin modelling are intriguing: these basins show significant petroleum potential and there is a break away from traditional petroleum plays based on structure.

Two 3-D images of the basin model

View from the north down of the layers in Carson Basin larger image [JPEG, 171.4 kb, 800 X 743, notice]

View to the north of the top of the salt layer (green in image on left) with an overlay of temperature. larger image [JPEG, 187.4 kb, 800 X 777, notice]

Outcomes

• The new biostratigraphic analyses of well samples, including two reference wells in the Jeanne d'Arc Basin, paleo-environmental interpretations and absolute ages result in a high precision geological model with regards to timing and deposition of lithological units.
• Creation of a functional digital seismic database will allow faster construction of stratigraphic horizon and depth surfaces with increased interpretational utility.
• Individual well summary well panels incorporating seismic setting, stratigraphy and petrophysical data, with interpretational comments puts all the well data at the fingertips of the user in digital form.
• Revision of the Paleogene-Neogene section (the over 1 km thick Banquereau Formation) gives a clearer defined geological history of this interval that is crucial for accurate basin modelling.
• Synthesis of a realistic 4-D petroleum system model, using state-of-the-art software and all available geo-data establishes a coherent geological history of the area. Assuming the presence of an Egret type source rock, the model shows that significant quantities of hydrocarbon will be generated and that their accumulation is mainly in stratigraphic traps.
• The project reduced exploration risk for the Carson and Salar Basins.

Oil (light-green lines and blobs) and gas (red lines) in the Hibernia Formation (yellow) in the Carson Basin, mainly in stratigraphic traps. The brick colour underlying the oil and gas stream lines represents the Egret type source rock. larger image [JPEG, 272.7 kb, 800 X 752, notice]

Partners

• Dalhousie University, Halifax: Apatite Fission Track data and Fluid Inclusion work
• GSC Calgary: Rock Eval analyses
• Canada Newfoundland Offshore Petroleum Board: donation of samples and sample time in the first year, seismic data exchanges
• Husky Energy, Calgary: donation of Husky seismic data set
• Encana, Calgary: donation of seismic lines
• Talisman Energy, Calgary : donation of seismic data
• PetroCanada, Calgary: donation of seismic lines and technical review time
• Norsk Hydro: initial access to basin modelling software
• Integrated Exploration Systems, Jülich, Germany for PetroMod8 basin modelling software

More Information

For more information about this project, contact Hans Wielens