| waiting on cement (WOC) |
pertaining
to the time when drilling or completion operations are suspended so that the cement in a
well can harden sufficiently. |
| wall cake |
also
called filter cake or mud cake. See filter
cake. |
| wall hook |
a device
used in fishing for drill pipe. If the upper end of the lost pipe is leaning against
the side of the wellbore, the wall hook centers it in the hole so that it may be recovered
with an overshot, which is run on the fishing string and attached to the wall hook. |
| wall sticking |
see differential sticking. |
| washing |
1. the
high-pressure spraying of the crude oil cargo to dislodge or dissolve clingage and
sediment from the walls, cross members, and lines in the compartments of a vessel during
the unloading operation. 2. the use of a
high-pressure water stream to dislodge clingage and sediment from the bulkheads, bottoms,
and internal structures of a vessel's cargo tanks. |
| wash over |
to
release pipe that is stuck in the hole by running washover pipe. The washover pipe
must have an outside diameter small enough to fit into the borehole but an inside diameter
large enough to fit over the outside diameter of the stuck pipe. A rotary shoe,
which cuts away the formation, mud, or whatever is sticking the pipe, is made up on the
bottom joint of the washover pipe, and the assembly is lowered into the hole.
Rotation of the assembly frees the stuck pipe. Several washovers may have to be made
if the stuck portion is very long. |
| washover |
the
operation during which stuck drill stem or tubing is freed using washover pipe. |
| washover shoe |
a device
employed to protect seals, seating nipples, etc., during mill-out operations. |
| washpipe |
1. a
short length of surface-hardened pipe that fits inside the swivel and serves as a conduit
for drilling fluid through the swivel. 2.
sometimes used to mean washover pipe. |
| water-base mud |
a
drilling mud in which the continuous phase is water. In water-gas muds, any
additives are dispersed in the water. Compare oil-base
mud. |
| water block |
a
reduction in the permeability of a formation caused by the invasion of water into the
pores. |
| water coning |
the
upward encroachment of water into a well caused by pressure drawdown from production. |
| water cushion (W/C) |
water
put into an empty string of pipe in a wellbore to prevent the pipe from being crushed by
pressure in the annulus. |
| water drive |
the
reservoir drive mechanism in which oil is produced by the expansion of the underlying
water and rock, which forces the oil into the wellbore. In general, there are two
types of water drive: bottom-water drive, in which the oil is totally underlain by water;
and edgewater drive, in which only a portion of the oil is in contact with the water. |
| waterflooding |
a method
of improved recovery in which water is injected into a reservoir to remove additional
quantities of oil that have been left behind after primary recovery. Waterflooding
usually involves the injection of water through wells specially set up for water injection
and the removal of water and oil from production wells drilled adjacent to the injection
wells. |
| water-in-oil emulsion |
see invert-emulsion mud, water
loss, fluid loss. |
| water well |
a well
drilled to (1) obtain a water supply to support drilling or plant operations, or (2)
obtain a water supply to be used in connection with an improved recovery program. |
| Webb-Wilson |
mechanical
tongs; sometimes used generically for all brands of tongs. |
| weevil |
shortened
form of boll weevil. See boll weevil. |
| weight |
1. in
mud terminology, refers to the density of a drilling fluid. 2. of a measurement, expresses degree of confidence in result of
measurement of a certain quantity compared with result of another measurement of the same
quantity. |
| weight cut |
the
amount by which drilling fluid density is reduced by entrained formation fluids or air. |
| weight indicator |
an
instrument near the driller's position on a drilling rig that shows both the weight of the
drill stem that is hanging from the hook (hook load) |
| weight up |
to
increase the weight or density of drilling fluid by adding weighting material. |
| well |
a hole
drilled in the earth for purpose of (1) finding or producing crude oil or natural gas; or
(2) providing services related to the production of crude oil or natural gas. |
| wellbore |
a
borehole; the hole drilled by the bit. A wellbore may have casing in it or it may be open
(uncased); or part of it may be cased, and part of it may be open. Also called a
borehole or hole. |
| well completion |
1. the
activities and methods of preparing a well for the production of oil and gas or for other
purposes, such as injection; the method by which one or more flow paths for hydrocarbons
are established between the reservoir and the surface. 2. the system of tubulars, packers, and other tools installed beneath the
wellhead in the production casing; that is, the tool assembly that provides the
hydrocarbon flow path or paths. |
| wellhead |
the
equipment installed at the surface of the wellbore. A wellhead includes such
equipment as the casinghead and tubing head. adj: pertaining to the wellhead (e.g.,
wellhead pressure). |
| well logging |
the
recording of information about subsurface geologic formations, including records kept by
the driller and records of mud and cutting analyses, core analysis, drill stem tests, and
electric, acoustic, and radioactivity procedures. See acoustic log, core analysis, driller's log, drill stem test, electric well log, mud analysis, and radioactivity well logging. |
| well permit |
authorization,
usually granted by a governmental conservation agency, to drill a well. A permit is
sometimes also required for deepening or remedial work. |
| well puller |
a member
of a well-servicing crew. |
| well servicing |
the
maintenance work performed on an oil or gas well to improve or maintain the production
from a formation already producing. It usually involves repairs to the pump, rods,
gas lift valves, tubing, packers, and so forth |
| wet gas |
gas that
carries a lot of liquids with it. |
| wetting |
the
adhesion of a liquid to the surface of a solid. |
| wetting agent |
a
substance or composition that, when added to a liquid, increases the spreading of the
liquid on a surface or the penetration of the liquid into a material. |
