Finding oil and gas in the early
1900s relied on luck. Early explorers looked for oil
seepages, certain types of rock
outcrops, and other signs that oil might exist below
ground. Oil diviners, or doodlebugs, were also used.
Today, technology has provided more than luck. Many
exploration companies are small and are called
"wildcats." Larger ones, such as Imperial Oil, are
involved in all aspects of the industry including
exploration. For more information on the history of
exploration, go to our feature “Wildcats and
Doodlebugs,” created by CKUA radio.
The explorer starts with a first
hand look at the area’s outcrop and surface
geological features. Sedimentary and
reservoir rocks must be present. Also all available data
about an area is examined, such as records from
previous wells and core samples. Cuttings and cores
from wells are important as they give geologists,
geochemist, and palynologists (studies pollens)
information on the age, chemistry, and porosity of a
formation. Any data gathered is placed into a
database that can be shared or purchased about a
specific area. Reservoirs are covered with thousands
of feet of rock that make it difficult to view the
deposits. After enough proof has been gathered the
exploration team must convince the managers and
investors to do a seismic survey. With solid data as
evidence, the company will approve the survey.
Waves, or a “shot,” are sent
underground to create a visual image of underground
rock formations. Geophones (jugs) are placed on the
ground. Vibrations are created either by dynamite or
by mechanical means at certain shot points on the
surface, and the geophones record the waves
that are reflected back. Different types of rock reflect
energy waves back to the surface, thus creating a picture
of the underground formations. With offshore
surveys, seismic surveys are restricted due to their
impact on marine life. To minimize the impact on
marine life, air guns using compressed air are
utilized to create the waves.
Two or three-dimensional seismic surveys, coupled with significant increases
in computational power, allow the industry to
develop fairly accurate models of the subsurface.
While these models can be viewed on a desktop
computer, three-dimensional
models can be viewed in huge theaters with curved
screens. These visualization centers allow the
geophysicist to see into the subsurface.
Three-dimensional seismic surveys enabled the
industry to improve its success rate. Reserves are
found with fewer wells, as well as with less waste and
environmental disturbance.
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