Magnetometers, towed by aircraft, help to detect magnetic
anomalies or to distinguish geologic features that might appear
similar from seismic data alone.
Air gun
Air gun array is most common technique used for seismic
surveying offshore. Compressed air is released from a chamber
to produce shock waves in earth.
Tightly closing a well so that hydrocarbons
cannot escape.
Casing
Steel lining used to exclude unwanted fluids; control well
pressures; support sides of well
bore. Casing Seat - lowest point
at which casing is set. Casing head
- top of casing set in well; part of casing that protrudes above
surface and to which control valves and flow pipes are attached.
Cement
Pumped into space between casing and
well bore wall in order to
hold casing in place.
A term to describe tools, equipment and instruments used
in well bore.
Drill bit
Located at end of drill-string
cutting head is generally designed with three cone-shaped wheels
tipped with hardened teeth. Drill bits used for extra-hard rock
are studded with thousands of tiny industrial diamonds.
Lifted continually to surface during drilling by a circulating-fluid
system driven by a pump. To facilitate removal of cuttings, mud is constantly circulated
down through drill pipe, out through
nozzles in drill bit, and then up to
surface through space between drill pipe and well
bore through earth (diameter of bit is somewhat greater than
that of pipe).
Drilling to determine whether hydrocarbons
are present.
Farm-in
Transfer of part of an oil
or gas interest in consideration
for an agreement by transferee(s) to meet certain expenditure
that would otherwise have to be undertaken by licensee(s).
Geophysics
Branch of science that applies physical principles to study
of planet earth.
Gravity surveys
Measure density variations in local rock masses. Surveys
are based on use of a gravimeter down bore
holes.
Horizontal
Drilling
Technique for cutting a bore
hole in geological strata in a horizontal, rather than normal
vertical, direction. (see also Horizontal
well)
Kick
Back pressure in well from invading oil
/ gas / water.
Complete process of pulling out and running in drill-string.
Seismic surveys
Measurements of seismic-wave travel. Seismic exploration
is divided into refraction and reflection surveys, depending
on whether the predominant portion of the seismic waves' travel
is horizontal or vertical. Refraction seismic surveys are used
in exploration. Seismic reflection surveys detect boundaries
between different kinds of rocks; this detection assists in mapping
of geologic structures. (See also 3D- Seismic.)
A remedial operation that results in creation of a new section
of well bore for purpose of
detouring around "junk", redrilling a lost hole or
straightening crooked holes.
Spud
Commencement of drilling operations.
Suspended
discovery
An oil or gas field identified
by a discovery well but not being
produced or developed.
Three-dimensional
Seismic / 3-D Seismic
Three-dimensional images created by bouncing sound waves
off underground rock formations; used to determine best places
to drill for hydrocarbons.
Top drive
Powerful electric motor that rotates whole drill-string
from top down.
Tripping in / out
Re-insertion of drill-string
/ Withdrawing drill-string.
Exploration well drilled in an unproven
area. (Term wildcatter comes from West Texas, where in early
1920s drilling crews encountered many wildcats as they cleared
locations for exploratory wells. Shot wildcats were hung on oil
derricks, and wells became known as wildcat
wells.)
