| IADC |
International Association of
Drilling Contractors |
| igneous
rock |
a rock mass formed by the
solidification of material poured (when molten) into the earth's crust or onto its
surface. Granite is an igneous rock. |
| impermeable |
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 |
a block with lead or another
relatively soft material on its bottom. It is made up of 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 and indicates the fish's position in the hole, i.e., whether
it is centered or off to one side. From this information, the correct fishing tool
can be selected. |
| impression
tool |
A lead-filled cylindrical device
used to ascertain the shape of a fish. |
| in
situ combustion |
the setting afire of some portion
of the reservoir in order that the gases produced by combustion will drive oil ahead of it
to the producing wells. |
| indexing
valve |
operates on the same principle as
an annular valve, except it requires pipe rotation for opening and closing operations. |
| indicator |
1.a dial gauge used on the rig to
measure the hookload. 2. substances in acid-base
that, in solution, change color or become colorless as the hydrogen ion concentration
reaches a definite value, these values varying with the indicator. In other
titrations, such as chloride, hardness, and other determinations, these substances change
color at the end of the reaction. Common indicators are phenolphthalein, and
potassium chromate. |
| inflatable
packer |
a type of packer used for
open-hole work, with inflatable packing elements |
| inflow |
see feed
in. |
| influx |
an intrusion of formation fluids
into the borehole, i.e., a kick. |
| inhibited
acid |
an acid that has been chemically
treated before the acidizing or acid fracturing of a well to lessen its corrosive effect
on the tubular goods and yet maintain its effectiveness. See acid fracture, acidize. |
| inhibitor |
an additive used to retard
undesirable chemical action in a product. It is added in small quantities to
gasolines to prevent oxidation and gum formation, to lubricating oils to stop color
change, and to corrosive environments to decrease corrosive action. |
| initial circulating pressure (ICP) |
the pressure at which a well that
has been closed in on a kick is circulated when well-killing procedures are begun |
| initial gel |
see initial gel strength. |
| initial
gel strength |
the maximum reading (defletion)
taken from a direct-reading viscometer after fluid has been quiescent for 10
seconds. It is reported in pounds per 100 square feet. See API-RP13B for details of
test procedure. |
| injection
gas |
1.a high-pressure gas injected
into a formation to maintain or restore reservoir pressure. 2. gas injected in gas lift operations. |
| injection
valve |
a poppet spring-loaded subsurface
valve run in on wireline, landed in a profile, to shut the well if injection ceases. |
| injection
well |
a well through which fluids are
injected into an underground stratum to increase reservoir pressure and to displace oil. |
| inland
barge rig |
a drilling structure consisting of
a barge upon which the drilling equipment is constructed. When moved from one
location to another, the barge floats. When stationed on the drill site, the barge
can be anchored in the floating mode or submerged to rest on the bottom. Typically,
inland barge rigs are used to drill wells in marshes, shallow inland bays, and areas where
the water covering the drill site in not too deep. Also called swamp barge.
See floating offshore drilling
rig. |
| input well |
an injection well used for
injecting fluids into an underground stratum to increase reservoir pressure. |
| insert pump |
a sucker rod pump that is run into
the well as a complete unit. |
| inside
blowout preventer |
any valve installed in the drill
stem to prevent a blowout through the stem. Mud can be pumped in but flow back up the stem
is prevented. Also called an internal blowout preventer. |
| instrument
hanger |
a hanger used to lock instruments
into seating nipple (pressure/temperature bombs, etc.). |
| insulated
flange |
a flange which incorporates
plastic pieces to separate the metal parts. |
| insulating
flange |
a flange equipped with plastic
pieces to separate its metal parts, thus preventing the flow of electric current.
Insulating flanges are often used in cathodic protection systems to prevent electrolytic
corrosion and are sometimes installed when a flow line is being attached to a wellhead. |
| intensifier |
a pressure-multiplier-type well
servicing mobile pump. |
| interfacial
tension |
the surface tension occurring at
the interface between two liquids that do not mix, such as oil and water.
Interfacial tension is caused by the difference in fluid pressures of the liquids. |
| intermediate casing string |
the string of casing set in a well
after the surface casing but before production casing is set. Keeps hole from caving
and seals off troublesome formations. Also called protection casing. |
