Technical
Thesaurus oil & gas
U
Ullage
The quantity a container
requires to completely fill it, i.e., the space in the container remaining
above the liquid level.
Ultra slim hole drilling
The application of mineral
drilling concepts and techniques for the purpose of low cost petroleum
exploration. See slim hole drilling.
Ultra-large crude carrier (ULCC)
An extremely large
ocean-going tanker of over 300,000 metric tonnes deadweight used to transport
crude oil from its source to a transhipment storage facility or direct to a
refinery.
Unconformity
A tectonic feature in which
strata are eroded and subsequently overlaid with younger strata (sometimes
angular), which are said to lie unconformably on the older strata; the actual
boundary between the two sets of strata.
Unconformity trap
A trap in which the escape
of hydrocarbons is prevented by impervious rocks unconformably overlaying the
reservoir. See unconformity.
Underwater acoustics
A special field of
technical acoustics dealing with the physics of sound propagation in the water.
Underwater position fixing
A method of position fixing
for surface vessels, submersibles or towed devices in relation to a network of
underwater acoustic beacons on the sea-bed with known relative positions.
Unit operator
The oil company in charge
of development and producing in an oil field in which several companies have
joined together to produce the field.
Unitisation
When owners of oil and/or
gas reserves pool their individual interests in return for an interest in the
overall unit, which is then operated by a single company on behalf of the
group, thus increasing efficiency.
Universal time
(UT)
Time as defined by the
rotational motion of the Earth and determined from the apparent diurnal motions
which reflect this rotation. Because of variations in the rate of rotation,
universal time is not rigorously uniform. Also called Greenwich Mean Time.
Unsaturated hydrocarbon
A hydrocarbon (such as
ethene or ethyne) containing one or more double or triple carbon-to-carbon
bonds in its molecule.
Up dip
Proceeding or lying upwards
in the direction of inclination of strata to the horizontal. The opposite of
down dip.
Uplift
The amount of oil that can
be recovered from a field annually before taxes have to be paid.
Upstream
A term referring to
industry operations before the refinery and marketing operations, i.e.
production, handling and transport.
UTM
Universal Transverse
Mercator: this projection is the most common surveying and mapping grid
projection. It is a system of cartesian coordinates that have been
predetermined to reference points on the Earth's surface. In this instance,