EnergyBC

Geological Basins

Offshore Basins with Oil and Gas Potential Along BC's West Coast

Queen Charlotte Basin - oil and gas prone

Winona Basin - gas prone

Tofino Basin - oil and gas prone

Georgia Basins - gas prone

The Queen Charlotte Basin (QCB) (from Chapter 2 Strong Report, 2002)

The QCB is the largest Tertiary age (65-1.8 million years old) basin on Canada’s West Coast. It represents an area of approximately 80,000 km²; (500 km long, 150 - 200 km wide) containing: 1. The Queen Charlotte Islands; 2. Offshore areas of Hecate Strait; 3. The Queen Charlotte Sound; 4. Dixon Entrance. The QCB is bounded to the south and north by Vancouver Island and Alaska. It is terminated to the east by the Coast Plutonic (Mountain) Complex and to the west by the large Queen Charlotte Fault that separates the North American Plate from the Pacific Plate. (Further details on the Queen Charlotte Basin.)

This basin is considered by geoscience to be the most promising untapped resource along the northeast Pacific continental margin of Canada and the United States, comparable in magnitude to the Cook Inlet Basin of southern Alaska. If the 1998 estimates by the Geological Survey of Canada (GSC) are accurate, the Queen Charlotte Basin resource might be three times larger than the Hibernia field of Newfoundland. However, the complex geology and anticipated high exploration risks associated with the Queen Charlotte resource require a great deal more information to be assembled and many exploration wells to be drilled before a truly reliable evaluation can be made.

The Georgia Basin

Limited drilling has been conducted within the onshore regions of the Georgia Basin, both on eastern Vancouver Island and in the Fraser Valley. Therefore most of the basin’s potential remains unevaluated. A recent resource assessment by the GSC has estimated that as much as 6.5 trillion cubic feet (TCF) of in-place natural gas exists in three conceptual play types within the confines of the Georgia Basin, about two-thirds (3.55 TCF) being in Canada and the remainder in Washington state. The available geochemical information indicates there is little potential for oil. There is some disagreement about these estimates, with some parties suggesting that they could be substantially lower.

The Winona-Tofino Basin

The Tofino assessment region combines both the Winona and Tofino Basins. The main potential for the Tofino Basin comes from on-shore gas showings on the Olympic Peninsula. Once again there is very limited exploration data and thus there are no clear estimates of resource quantities.

Oceanographic and Meteorological Characteristics - Appendix 14 Strong Report

Although the Hecate Strait is somewhat protected from the Pacific Ocean by the Queen Charlotte Islands, the size of the water body (55 km to 120 km wide), its morphology and oceanographic and weather situation make it susceptible to severe conditions. The Dixon Entrance to the north and the Queen Charlotte Sound to the south of Hecate Strait have oceanographic conditions that are somewhat less severe.

Bathymetry

The majority of the Hecate Strait has relatively shallow water depths of 200m or less, however it reaches up to 300m deep in the south. Much of the Queen Charlotte Sound is also shallower than 200m but can get as deep as 400m in the troughs. The Dixon Entrance shallows from 400m to 200m landward, with the exception of the 35m Learmonth Bank at the mouth of the Dixon Entrance. The water depths in the Hecate Strait and Queen Charlotte Sound are common to those encountered in offshore petroleum exploration at other locations. As such, they do not present any technological restrictions or difficulties. For comparison with the east coast (Jeanne d’Arc Basin), the discovery well Chevron et al Hibernia P-15 was drilled to a total depth of 4407m in 80m water depth. In the same Jeanne d’Arc Basin, the discovery well Husky/Bow Valley et al Whiterose N-22 was drilled to 4628m in a 122m water depth.

Climate

The climate of Hecate Strait can be characterized as temperate with a strong westerly onflow of moist marine air. However it has some of the strongest winds in Canada, with wind speeds of up to 200 km/hr having been recorded (Cape St. James). Due to topographic highs created by the coastal mountains, the winds tend to blow north and south along the length of the straight. These winds are driven by seasonally changing surface ocean temperatures and barometric pressure systems.

Air temperatures have been measured continuously over the past 50 years in the region and display a much larger range than the water temperatures. For example, typical air temperatures on land in the village of Massett on the Queen Charlotte Islands are 18°C in the summer and 4°C in the winter. Average air temperatures over the water in the area seasonally vary about 9°C, with a mean temperature of 12°C in July and 3°C in January.

Some credit from above text to British Columbia Offshore Hydrocarbon Development: Report of the Scientific Review Panel prepared by Strong, David, Patricia Gallagher and Derek Muggeridge, January 2002