Technical
Thesaurus oil & gas
Letter
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