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.
A term to describe tools, equipment and instruments used
in well bore.
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).
Complete process of pulling out and running in drill-string.
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.)
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