Technical
Thesaurus oil & gas
W
W.T.I.
The West Texas Intermediate
grade has become the "marker" crude in
Waiting on cement
Pertaining to, or during
the time, when drilling or completion operations are suspended so the cement in
a well can harden sufficiently.
Wall cake
See filter cake and mud
cake.
Wall sticking (of drill pipe)
A condition downhole when a
section of the drill string becomes stuck or hung-up in the deposit of filter
cake on the wall of the bore hole due to excess differential pressure.
Wash-over pipe
A pipe run at the end of
drill pipe or tubing which can slide over a "fish" left in the hole
to wash out the space between the fish and the wall of the hole and thus free
the fish which will make fishing operations easier.
Wastage
By-product that is not
marketed (i.e. flare, acid gas, fuel, refrigerant).
Water column
A vertical continuum of
water from sea surface to sea-bed.
Water coning
The encroachment of water
in a well bore in a water-drive reservoir owing to an excessive rate of
production. The water below the oil moves upward to the well bore through
channels, fissures, and permeable streaks leaving the oil sidetracked and
by-passed.
Water drive
A recovery process in which
oil or gas is driven out of a reservoir by the pressure of underlying water.
Water drive reservoir
An oil or gas reservoir in
which pressure is maintained by the influx of water as the oil and/or gas is
produced. The influx of water may be a natural flow of formation water or water
pumped into the reservoir via injection wells.
Water flooding
A method of pressure
maintenance and secondary recovery in which water is injected through input
(injection) wells to drive oil to the production wells.
Water hammer
The energy developed by the
sudden stoppage of fluid in motion.
Water injection
A process whereby treated
water is pumped into the reservoir rock in order to maintain the reservoir
pressure.
Water/oil up-to
The depth (TV or AH) of the
top of the deepest oil or water bearing sand. The sand immediately above this
would contain a different fluid, either gas or oil.
Watered-out
Is when a production well
is shut-in due to its unacceptably high proportion of water production.
Wave (electromagnetic)
Wave of associated electric
and magnetic fields characterised by variations of the fields. The electric and
magnetic fields are at right angles to each other and to the direction of
propagation. An electromagnetic wave is coherent if the phase-time relationship
is constant throughout the propagation path.
Wave (propagation)
The travel of waves through
or along a medium.
Wave length
The distance between
corresponding points of two successive periodic waves in the direction of
propagation, for which the oscillation has the same phase. Unit of measurement
in metres. Also written as one word.
Wax
Solid hydrocarbon which is
present in some crude oils, especially in paraffinic crudes. Wax deposits in
pipelines and equipment can cause mechanical problems.
Weather forecast
The expected wind, wave and
weather conditions during the next few days.
Weather window
The part of the year when
the weather can normally be expected to be suitable for carrying out offshore
operations such as pipeline laying or platform installation. An extended
weather forecast indicating that specific maximum winds and wave conditions are
not expected to be for a minimum duration.
WEC
World Energy Council
Weevil
Shortened version of
boll-weevil. See boll-weevil.
Weight indicator
An instrument near the
driller's position on a drilling rig. It shows both the weight of the drill
stem that is hanging from the hook (hook load) and the weight that is placed on
the bit by the drill collars (weight on bit).
Weighting material
A material that has high
specific gravity and is used to increase the density of drilling fluids or
cement slurries.
Well bore
The hole in the rock made
by the drill bit.
Well completion
The activities and methods
necessary to prepare a well for the production of oil and gas; the method by
which a flow line for hydrocarbons is established between the reservoir and the
surface. The method of well completion used by the operator depends on the
individual characteristics of the producing formation or formations. These
techniques include open-hole completions, sand exclusion completions,
tubingless completions, multiple completions, and miniaturised completions.
Well logging
A comprehensive record of
all data collected during the drilling of a well, enabling a highly detailed
picture of the strata to be built up.
Well service
To include services to a
well such as workover, completion, well test, wellhead service, wireline
service.
Well slot
A fixed location (opening)
on the offshore platform drilling floor from which a subsea well can be
drilled.
Wellhead
The control equipment
fitted to the top of a well casing, incorporating outlets, valves, blowout
preventers, etc.
Wet barrels
Crude oil or product
physically traded (in distinction to "paper" and
"electronic" barrels).
Wet natural gas
Natural gas which contains
large amounts of associated liquids.
Wet tree
A subsea wellhead where the
equipment is exposed to the sea.
Whipstock
A wedge-shaped piece of
equipment placed at the bottom of a well, thus forcing the bit and drill pipe
to deviate from their original direction when drilling is resumed.
White products
A term used to denote the
lighter, more volatile petroleum products. Sometimes used to denote gasolines,
naphthas and kerosine, it is also frequently used in a broader meaning to
include middle distillates in distinction to black oils which covers all
distillation residual products. The term should not be confused with white oils
which relates to colourless, highly refined light lubricating oils used in
pharmaceutical and other consumer product industries.
Wildcat
An exploration well drilled
without knowledge of the contents of the underlying rock structure.
Wildcat appraisal well
An appraisal well drilled
with minimum preliminary information about the underlying structure and
conditions; it usually follows a wildcat well which reports shows of oil or
gas.
Wind Power
Nearly all the wind power in
the world is installed in power stations connected to electricity grids and
consists of a certain number of wind turbines situated in rural areas
characterised by appropriate wind conditions. In Europe wind plants usually
consist of no more than a few dozen turbines whereas in the so-called wind
farms in California –where more space is available -hundreds of turbines are
installed in the same area. Wind technology is virtually mature and -in
particularly windy sites -it can prove competitive from an economic point of
view compared to traditional sources of energy. At the end of 1999 the
generating capacity from wind in worldwide installations amounted to about
13,000 MW. In
Wing valve
Valve on a christmas tree
which will close off or allow flow from the well to the flow line.
Wiper trip gas
Gas encountered in the
bottom of a drilling well after pulling and re- running a number of stands of
drill string in order to check the hole condition.
Wireline
Any line or cable used for
downhole operations. There are normally two types of wireline: piano -which is
a thin single strand of high tensile steel which is used to lower instruments
or tools into a well; electric - wirelines which are normally used for surface
recording instruments such as logs.
Witness mark
A mark placed at a known
distance and direction from a property corner, base terminal or survey station
to aid in its recovery and identification.
Workover
The process whereby a
completed production well is subsequently re- entered and any necessary
cleaning. repair and maintenance work done.
Workpack
A workpack refers to a
single inspection of a structure. Tasks are defined per Workpack. Event data is
captured for the currently active Workpack.
World geodetic system (WGS)
A world geodetic reference
system developed by the
WOW
“Waiting on weather"
WPC
World Petroleum Congress