At the beginning, the crew thought the well was a gas discovery,
but there were signs of something more. Past 1,500 metres, the
drilling speeded up and the first bit samples showed free oil in
the reservoir rock (dolostone). At a depth of 1,544m they had
drilled into a Devonian oil-bearing carbonate mound, dolostone.
Leduc was the largest discovery in Canada in 33 years, and
triggered a boom that would lead to the discovery of the bulk of
Canada's oil reserves, hidden deep in the limestone and dolomite
reefs of the Devonian.
This famous discovery marked the birth of Western Canada's
modern oil industry and has been called one of the most important
economic discoveries in Canada's history. In 1974 this well stopped
production, it had produced about 317,000 barrels of oil and 9
million cubic meters of natural gas.
The discovered oil was formed 350 to 380 million years ago in
the Devonian Period (hence the chosen name of the town of Devon
just north of Leduc #1). Most geologists today agree that crude oil
forms over million of years from the remains of tiny aquatic plants
and animals that are exposed to the combined effects of time and
temperature. In other words, oil forms from organic matter that is
either "cooked" deep within the earth for long periods of time at
low temperatures, or "cooked" for short periods of time at high
temperatures.
Dolostone is a carbonate sedimentary rock made of dolomite
(calcium magnesium carbonate). Oil dolostone (bituminous dolostone)
is a dolostone petroleum reservoir rock that contains petroleum
crude oil in its joints which originally migrated into it from its
oil shale source rock.
Sedimentary rocks cover about three-quarters of the earth's
surface and form more than 90 percent of Alberta's bedrock surface.
Leduc #1 is within close proximity of the Rocky Mountains which
consist mostly of the chemical rocks limestone and dolostones.
These coordinates will take you just outside the Canadian
Petroleum Discovery Centre which is situated at the Leduc #1
historical site. This well was a key factor to Alberta's rich
petroleum heritage which historically have been focused on
agriculture. The discovery at Leduc would be the seminal event in
the Canadian oil industry, triggering an oil boom whose effects are
still widely visible today.
To log this cache:
- You must post a picture in your log entry of yourself holding
your GPS receiver in front of the Leduc #1 oil well.
- You must also send an email indicating the year in the bottom
right corner of the plaque on the large "dolostone" rock sample in
the glass enclosure at the posted coordinates. Please include an
estimated height of this sample.
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