The Queen Charlotte Basin is the largely structural basin under the offshore continental shelf, between Queen Charlotte Islands, Vancouver Island, and British Columbia plains, roughly coinciding with the physiographic region called Hecate Depression.
The term Queen Charlotte Basin usually refers to Cenozoic rock, but it is based on what appears to be a thick Mesozoic succession. The Queen Charlotte Basin was formed by a period of extension, including depletion and volcanism during the middle era of the Kenozoic. The large Cenozoic plenum suggested by magnetic data in the southeastern part of the Queen Charlotte Basin appears to be associated with Anahim hotspots.
Video Queen Charlotte Basin
Geology
The renewed new interest in Canada's western shelf basin results from the widespread expectation that a long-term government moratorium on offshore exploration there may soon be lifted. The best oil prospects appear to be in the Cretaceous reservoir in the southwest of the Queen Charlotte Basin, in the western Queen Charlotte Sound.
With oil seeps from rocks of all ages, two dozen wells were drilled in the Queen Charlotte and Tofino areas before the 1970s; many lands were mapped in the 1980s and 1990s. However, the islands of Vancouver and Queen Charlotte mostly have no limestone. The Hecate Strait does not seem to have adequate reservoir and reserve rock, and offshore wells do not significantly test the Mesozoic horizon. The rocks on the mainland are crystals. The Tofino, Winona, Georgia and Juan de Fuca basins do not have significant source rocks. In contrast, the southwest Charlotte Queen basin appears to contain a stack of sources, reservoirs and limestone layers, mostly in the depths of oil-window burials, as well as large-block fault trap structures.
While some workers (eg Lyatsky and Haggart, 1993, Lyatsky, 2006) regard the Mesozoic horizon as the main oil exploration target, others (eg, Dietrich, 1995; Hannigan et al., 2001) focus more on the Cenozoic over it. stone. Rohr and Dietrich (1992) consider that the Queen Charlotte Basin has been largely formed by strikes in Cenozoic. On the other hand, Lyatsky (1993, 2006) considers a significant strike-slip movement to be impossible in this basin since at least the Final Oligocene, based on kinematic indicators and cross-sectoral links of major faults and dated dikes; on the contrary, it views the underground Kenozoic evolution to become a product of reactivation of older networks of block-breaking blocks.
The economic basement of the Queen Charlotte Basin area is a thick and thick Triassic flood basal, grounded with partly metamorphosed rocks. Above, high-quality source rocks are located at ~ 1,000 meters (0.62Ã, mi) -making a Triasik-Lower Hierassic Up collection, with gravel Type I and II petroleum and TOC (total organic carbon) up to 11%. Geochemical evidence suggests these stones provide the bulk of chin oil, and the large pulse of the oil generation and migration is in the Kenozoic. The Upper Clascaceous clastic succession above, ~ 3,000 meters (1.9 mi) thick, has a negligible source potential but contains high quality reservoirs with a porosity of ~ 15% or more. Above, mostly off the coast, are Cenozoic cliffs, sandstone and volcanic deposits, up to ~ 6,000 meters (3.7 mi) thick in some depocenters that are bounded by fractures.
Cenozoikum deposits have gas-prone type III and II, with TOCs up to 2.5% locally. However, the clay product of the feldspar decomposition greatly decreases its permeability, especially at the basal level. The reservoir quality sandstone facies are found almost near the top of this unit, where the migration route from below and the above seal may be inadequate. Cenozoic deposits thus appear to be dominant, perhaps with some secondary exploration targets.
Studies of stratigraphy and sedimentology show that the Triassian Jura source rocks are deposited in a wide rack covering the whole region and so on. However, the Cretaceous basin is confined to the west of Queen Charlotte island and northwest of Vancouver Island, with the highlands to the east releasing detritus. Western Queen Charlotte Sound may be part of the same Cretaceous basin, while east of Queen Charlotte Sound and Hecate Strait largely lose their existing source rock and receive some non-marine, Cretaceous deposits. Cenozoic caprock, with thick block blocks to block, then envelops the Strait of Hecate and Queen Charlotte Sound.
Western Queen Charlotte Sound should contain a heap of lucrative reservoir-seal sources. The gravity data also shows the immense thickness of the low-density (sediment?) Rocks that exist beneath the Queen Charlotte Charlotte west but not elsewhere in the Queen Charlotte Basin.
Patrock-breaching violations are less common in Queen Charlotte Sound than in the northern part of the basin; The Queen Charlotte Basin is not too pressed. Regional geological and geophysical correlations show the main Mesozoic bloc-error network reactivated in Cenozoic. The seismic and gravity data show the error-bound Cenozoik depocenter and the raised block being relatively broad in the western Queen Charlotte Sound.
Some warning. Lime rocks, kept near their home areas, tend to be immature petrology, and secondary porosity in them may be difficult to predict. Source rocks buried beneath the deepest depositor may be too high. Some traps can be breached by the Neogen error: one of the oil dyes found offshore, showing oil passing through this Cenozoic rock and escaping. The major influence on local hydrocarbon maturation levels in the Queen Charlotte Islands is close to most of the Jurassic and Cenozoic frozen plakons. Similar potential field anomalies show that massive rock bodies may exist in the eastern part of the Queen Charlotte Sound, and the correlation with the main rock cluster of Isabela volcanic northern belt puts their age in the Miocene. Pluton-related magnetic anomalies do not seem significantly far west of Queen Charlotte Sound.
Maps Queen Charlotte Basin
See also
- Anahim hotspot
Note
References
- Dietrich, J.R., 1995. Potential petroleum resources from the Queen Charlotte Basin and beyond, Canada's west coast; Canadian Petroleum Geology Bulletin, v. 43, h. 20-34.
- Hannigan, P.K., Dietrich, J.R., Lee, P.J., and Osadetz, K.G., 2001. Potential of Petroleum Resources from Sediment Sediments in Pacific Margin of Canada; Canada Geological Survey, Bulletin 564, 72 p.
- Lyatsky, H.V., 1993. Basement structure and evolution under the control of the Queen Charlotte Basin, Canada's west coast; Tectonophysics, v. 228, p. 123-140.
- Lyatsky, H.V., 2006. Frontier next door: geology and hydrocarbon assessment of the western offshore sedimentary basin of Canada; Recorders (Canadian Society of Exploration Geophysicists), v. 31, no. 4, p. 66-75.
- Lyatsky, H.V. and Haggart, J.W., 1993. Petroleum exploration model from the Queen Charlotte Basin area, British Columbia offshore; Journal of the Earth Sciences of Canada, v. 30, h. 918-927.
- Rohr, K.M.M. and Dietrich, J.R., 1992. Tectonic strike and development of the Queen Charlotte Tertiary Basin, offshore western Canada: evidence of seismic reflection data; Basin Research, v. 4, p. 1-19.
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