Technical Thesaurus oil & gas
Letter
Hard water
Water which does not form a permanent
lather with soap due to the presence of dissolved salts in the water. Hardness
is of two types: temporary hardness, due to the presence of bicarbonates;
permanent hardness, due to the presence of sulphates. Both types of hardness
can be removed using ion exchange methods.
Head
The height of the surface of a liquid
above a specific point, especially when used as a measure of the pressure at that
point.
Heading
The direction in which the
longitudinal axis of a craft is pointed, usually expressed in degrees from
north (true, magnetic or compass).
Heat exchanger
Equipment in which heat is
transferred between liquids or liquids and gases through a tubular wall on a
continuous basis. The transfer of heat is achieved by conduction through the
tube walls from a hot to relatively cool material by the countercurrent, or
concurrent, flow of hot and cold materials.
Heave
The up-and-down movement of a
semi-submersible drilling platform or drill ship.
Heave compensation
The removal of the effect of wave
motion from the recorded sea-bed profile.
Heavy crude
Crude oil with a high specific
gravity and a low API gravity due to the presence of a high proportion of heavy
hydrocarbon fractions.
Heavy fractions (heavy ends)
The high-molecular-weight,
high-boiling-point fractions that emerge from the lower part of a fractionating
column during the oil refining process.
Height
The vertical distance of a level, a
point or an object considered as a point, measured from a specified datum. The
vertical dimension of an object.
Height of tide
The vertical distance from the chart
datum to the level of the water at any time.
Helipad
The platform on an offshore
installation on which helicopters land.
Heliport
A land base from which helicopters
operate.
Helium
A naturally occurring inert gas that
is mixed with oxygen to provide a safe breathable atmosphere for divers working
under high pressure.
Heptane
The saturated hydrocarbon (alkane)
with seven carbon atoms in its molecule (C7H 16); the seventh member of the
paraffin series -a liquid under normal conditions.
Heterogeneous
A substance that consists of more
than one phase and is not uniform, such as colloids, emulsions, etc. It has
different properties in different parts.
Hexane
The saturated hydrocarbon (alkane)
with six carbon atoms in its molecule (C6H 14) the sixth member of the paraffin
series -a liquid under normal conditions.
Hierarchical Tree
The hierarchical tree represents a
graphical view of the Structure being inspection. Each entry in the
Hierarchical tree is called a node. The nodes may be a Structure Type, a
Structure Name, a Sub-structure or a Component. Structure Types are always at
the highest level on the tree. The other node types are assigned below the
Structure Type.
High resolution
A seismic method widely used for
hazard detection in the context of site surveys.
High water (HW)
The highest level reached at a place
by the water surface in one oscillation. Also called high tide.
Hindcast
A study of previous wind, wave and
weather events for estimation of down time.
Hoist
An arrangement of pulleys and wire
rope or chain used for lifting heavy objects; a winch or similar device; the
drawworks. See drawworks.
Hoisting drum
The large, flanged spool in the
drawworks on which the hoisting cable is wound. See drawworks.
Hole
Another name for the well bore.
Hole opener
A type of reamer used to increase the
diameter of the well bore below the casing. The special tool is equipped with
cutter arms that are expanded against the wall of the hole and by rotary action
reams a larger diameter hole.
Homogeneous
Of uniform or similar nature
throughout; or a substance or fluid that has at all points the same property or
composition.
Homologous series
A series of hydrocarbons in which
successive members differ in molecular composition by CH2, e.g. the alkanes,
alkenes and alkynes.
Hook
A large, hook-shaped device from
which the swivel is suspended. It is designed to carry maximum loads ranging
from 100 to 650 tons and turns on bearings in its supporting housing. A strong
spring within the assembly cushions the weight of a stand (
Hopper
A large funnel or cone shaped device
into which components (as powdered clay or cement) can be poured in order to
uniformly mix the components with water (or other liquids). The liquid is
injected through a nozzle at the bottom of the hopper. The resulting mixture of
dry material and liquid may be drilling mud to be used as the circulating fluid
in a rotary drilling operation or maybe cement slurry used to bond casing to
the borehole.
Horizon
A stratum or layer of strata assumed
to have been laid down in a continuous manner.
Horizontal control datum
The position on the spheroid of
reference assigned to the horizontal control (triangulation and traverse) of an
area and defined by (1) the position (latitude and longitude) of one selected
station in the area, and (2) the azimuth from the selected station to an adjoining
station. See datum (geodetic).
Horsepower
A unit of power. One horsepower is
equivalent to approximately 746 watts.
Hotel platform/rig
See accommodation rig.
HUET
Helicopter Underwater Escape
Training. A special course for offshore workers who travel to and from work by
helicopter. Prepares workers to deal with an accidental ditching in water.
Hundred year storm
A combination of storm conditions
(wave height and sustained wind speed) that should, on average, only occur once
every hundred years in a particular area, offshore structures are designed to
withstand such storms.
Hurricane
A tropical cyclone with winds
exceeding 63 knots (storm force). Also known as severe tropical cyclone or
typhoon.
Hybrid photovoltaic-diesel systems
The electrification of very small
areas isolated from the electricity grid (minor islands, small mountain
villages, etc.) is one of the most competitive applications compared to
traditional systems. The reliability of the electric service that these plants
can provide is guaranteed by the presence of a power unit for partial use when
there are prolonged sunless periods. Furthermore these plants can be designed
to be entirely automated and remote-controlled.
Hybrid platform
A gravity platform whose base and
storage area are made of reinforced concrete but whose upper sections are made
of steel.
Hydrate
A compound formed by the chemical
union of water with a molecule of some other substance. Gas hydrates formed
from water and, for example methane, may cause plugging of the tubing and flow
lines of gas wells or gas transmission lines.
Hydrate point
The conditions of pressure and
temperature of a gas under which hydrates will start to form (in the presence
of free water).
Hydraulic fracturing
An operation in which a specially
blended liquid is pumped down a well and into a formation under pressure high
enough to cause the formation to crack open. The resulting cracks or fractures
serve as passages through which oil can flow into the well bore. See formation
fracturing.
Hydraulics
The branch of applied science that
deals with fluids in motion.
Hydrocarbon aerosol propellant
A hydrocarbon used in aerosol sprays
to drive out and atomise the contents usually high-purity isobutane plus a
small amount of propane.
Hydrocarbons
Compounds containing only the
elements hydrogen and carbon. They may exist as solids, liquids or gases.
Hydrocyclones
Cone-shaped centrifuges used for
removing sand, silt and other solid particles from drilling mud; also called
desanders and desilters.
Hydrogenation
The process whereby a double
carbon-to-carbon bond is converted to a single bond by addition of hydrogen.
Hydrographic society
International learned society based
in the
Hydrographics
The wider term concerning the
physical situation between surface and sea-bed. In particular survey terms extending
below the sea-bed.
Hydrography
The branch of applied science which
deals with the measurement and description of the physical features of the
navigable portion of the Earth's surface and adjoining coastal areas, with
special reference to their use for the purpose of navigation.
Hydromatic brake
A device mounted on the end of the
drawworks shaft of a drilling rig. The hydromatic brake (often simply called
the hydromatic) serves as an auxiliary to the mechanical brake when pipe is
lowered into the well. The braking effect in a hydromatic brake is achieved by
means of a runner or impeller turning in a housing filled with water.
Hydrometer
An instrument used to measure the
density or specific gravity of a liquid.
Hydrophone
An underwater microphone used to
detect sound signals travelling through the water.
Hydrostatic head
The pressure exerted by a column of
fluid, equalling the height of the column times the fluid density.
Hydroxyethylcellulose
A derivative of ethylene and
cellulose added to drilling muds as a suspension agent; also widely used in the
textile and paper industries.
Hyperbaric chamber
A chamber whose interior can be
maintained at a high pressure in order to allow saturation divers to live under
the same pressure conditions at which they work underwater; a chamber in which
such divers work or are transported under water.
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