Technical
Thesaurus oil & gas
H
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.