IADC abbr: International Association of Drilling Contractors.
impeller n: a set of mounted blades used to impart
motion to a fluid air or gas (such as, the rotor of a centrifugal pump).
impermeable adj: preventing the passage of fluid. A
formation may be porous yet impermeable if there is an absence of connecting
passages between the voids within it. See permeability.
impression block n: a block with lead or another
relatively soft material on its bottom. It is made up on drill pipe or tubing
at the surface, run into a well, and set down on the object that has been lost
in the well. The block is retrieved and the impression is examined. The
impression is a mirror image of the top of the fish; it also indicates the
fish’s position in the hole, for example, whether it is centered or off to
one side. From this information, the correct fishing tool may be selected.
induction log n: an electric well log in which the
conductivity of the formation rather than the resistivity is measured. Because
oil-bearing formations are less conductive of electricity than water-bearing
formations, an induction survey, when compared with resistivity readings, can
aid in determination of oil and water zones.
inflatable packer n: a packer with an element that
inflates by means of gas or liquid pumped from the surface through a line. It
is deflated by means of slots that can be opened to allow the gas or liquid to
flow out. They are used when a temporary packer is needed in a hole.
injection gas n: 1. a high-pressure gas injected
into a formation to maintain or restore reservoir pressure. 2. gas injected in
injection log n: a survey used to determine the
injection profile, that is, to assign specific volumes or percentages to each
of the formations taking fluid in an injection well. The injection log is also
used to check for casing or packer leaks, proper cement jobs, and fluid
migration between zones.
injection water n: water that is introduced into a
reservoir to help drive hydrocarbons to a producing well.
injection well n: a well through which fluids are
injected into an underground stratum to increase reservoir pressure and to
displace oil. Also called input well.
injector head n: a control head for injecting coiled
tubing into a well that seals off the tubing and makes a pressure tight
inland barge rig n: an off shore drilling structure
consisting of a barge on which the drilling equipment is constructed. It is
positioned on location, then the barge is sunk.
insert n: 1. a cylindrical object, rounded, blunt, or chisel-shaped on
one end and usually made of tungsten carbide, that is inserted in the cones of
a bit, the cutters of a reamer, or the blades of a stabilizer to form the
cutting element of the bit or the reamer or the wear surface of the
stabilizer. Also called a compact.
insert pump n: a sucker rod pump that is run into
the well as a complete unit.
intake valve n: 1. the mechanism on an engine
through which air and sometimes fuel are admitted to the cylinder. 2. on a mud
pump, the valve that opens to allow mud to be drawn into the pump by the
pistons moving in the liners.
intermediate casing string n: the string of casing
set in a well after the surface casing but before production casing is set to
keep the hole from caving and to seal off formations. In deep wells, one or
more intermediate strings may be required.
internal cutter n: a fishing tool containing
metal-cutting knives that is lowered into the inside of a length of pipe stuck
in the hole to cut the pipe. The severed portion of the pipe can then be
returned to the surface. Compare external cutter.
International Association of Drilling Contractors (IADC) n:
an organization of drilling contractors, oil and gas companies, and service
companies that sponsors or conducts research on education, accident
prevention, drilling technology, and other matters of interest to its
membership and their employees. Its official publication is The Drilling
Contractor. Address: Box 4287; Houston, TX 77210; (281) 578- 7171; fax (281)