Discover the IHRDC Energy Glossary_beta

LACT

Lease Automatic Custody Transfer.

LACTI Chart

LAN

Local Area Network; the main information network connecting controllers, servers, clients, and workstations in a typical plant

LC Oscillator

An oscillator in which the tuned circuit has an inductor and a capacitor connected in parallel.

LED

An LED is a light-emitting diode.

LOCDIP

LOCDIP computations use pad-to-pad correlations made over short intervals centered on the bed boundaries, as defined by the major inflection points on the micro-resistivity curves.

LVP Motor Controller

A motor controller that provides low voltage protection (LVP); requires an operator to restart the motor when voltage returns to normal

LVR Motor Controller

A motor controller that provides low voltage release (LVR); enables the motor to restart automatically when voltage returns to normal

Label

In PLC programming, the number indicating the destination of a jump. Also, the name given to a device to identify it in a ladder diagram (synonym for alias, tag, or symbol). In hazardous materials, a diamond-shaped tag or sticker identifying contents and associated risks.

Laboratory

A facility where the “laboratory use of hazardous chemicals” occurs. It is a workplace where relatively small quantities of hazardous chemicals are used on a non-production basis.

Laboratory scale

Work with substances in which the containers used for reactions, transfers, and other handling of substances are designed to be easily and safety manipulated by one person. “Laboratory scale” excludes those workplaces whose function is to produce commercial quantities of materials.

Laboratory use of hazardous chemicals

Handling or use of such chemicals in which all of the following conditions are met:1. Chemical manipulations are carried out on a “laboratory scale”;2. multiple chemical procedures or chemicals are used;3. the procedures involved are not part of a production process, nor in any way simulate a production process; and4. “protective laboratory practices and equipment” are available and in common use to minimize the potential for employee exposure to hazardous chemicals.

Laboratory-type hood

A device located in a laboratory, enclosed on five sides with a movable sash or fixed partial enclosed on the remaining side; constructed and maintained to draw air from the laboratory and to prevent or minimize the escape of air contaminants into the laboratory; and allows chemical manipulations to be conducted in the enclosure without insertion of any portion of the employee's body other than hands and arms. Walk-in hoods with adjustable sashes meet the above definition provided that the sashes are adjusted during use so that the airflow and the exhaust of air contaminants are not compromised and employees do not work inside the enclosure during the release of airborne hazardous chemicals.

Labyrinth

Type of seal on the expander-compressor which has a series of teeth machined on the impellers or seal rings to a small clearance between the teeth and shaft.

Labyrinth Seal

A seal made up of a set of grooves and ridges that correspond to another set of grooves and ridges on, for example, a turbine shaft

Lacustrine deposits

Lacustrine deposits are sedimentary rock formations that occur in the bottom of lakes.

Lag

In process control, the time between when a process variable begins to respond and when it has substantially re-stabilized (also called the time constant). The total delay caused by resistance, capacitance, and dead time. In geology, a deposit of coarse material left behind after finer materials have been removed by wind, water, or tidal action.

Laminar Flow

Laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection.

Lamination

Lamination develops in fine grained sediment when fine grained particles settle, which can only happen in quiet water.

Lamination, Laminated, Laminae

A small-scale sequence of fine layers (laminae) occurring in sedimentary rocks, normally smaller and less pronounced than bedding layering. Lamination is normally regarded as planar structures one centimeter or less in thickness, whereas bedding layers are greater than one centimeter.

Landfill

A pit or area in which wastes are buried

Lang Lay

A form of wire rope construction in which the strands of the rope and the wires that make up the strands spiral in the same direction

Lantern Ring

A ring located between rings of packing and designed to distribute gland sealing fluid

Lanyard

A flexible line of rope, wire rope, or webbing with connectors at each end.

Lap-joint flange

A four-piece flange; a lipped piece of pipe that welds to existing pipe, with the flange half sliding up to the lip on each pipe half. Lap-joint flanges swivel around pipe, so two-holing is not required.

Latent Defect

This type of damage allows a device to work properly for the most part, but over time the small amount of damage might affect the life of the device or its ability to function. The issue with latent defects is that the item usually passes testing and can move to the next step of a process where it may fail.

Latent Heat

Energy that, when added to or taken away from a substance, causes a change in state (phase change) but not in temperature.

Latent Heat Transfer

A heat transfer process that causes a phase change rather than a temperature change.

Latent Heat of Condensation

The amount of heat that must be removed from a vapor to change it into a liquid at a particular temperature and pressure without producing a change in temperature.

Latent Heat of Fusion

The amount of heat required to melt a substance without producing a change in temperature or pressure

Latent Heat of Vaporization

The amount of heat required to completely change the phase of a liquid to a vapor at a certain temperature and pressure.

Laterolog

A type of resistivity electrode device that measures resistivity by injecting electric current into the formation and measuring the potential drop. Most laterologs use cylindrical electrodes that average resistivity azimuthally; azimuthal laterologs use radially segmented electrodes that respond to resistivity in the direction each segment is facing.

Law of Energy Conservation

The law stating that energy can neither be created nor destroyed, only altered in form.

Lay

The manner in which the wires and the strands of a wire rope are laid, or twisted

Leaching

The process by which soluble constituents are removed from a solid, such as soil, by liquid passing through it.

Lead

A lead in hydrocarbon exploration is a subsurface structural or stratigraphic feature with the potential to have entrapped oil or natural gas. When exploring a new area, or when new data becomes available in existing acreage, an explorer will carry out an initial screening to identify possible leads. Further work is then concentrated on the leads with the intention to mature at least some of them into drillable prospects.

Leak-off in Hydraulic Fracturing

Leak-off in the hydraulic fracturing process is termed as the influx of fracturing fluid into the adjacent fracture path layers.

Leakage current

The amount of current flow across the collector-base junction of a properly biased transistor. Each transistor has a specified amount of leakage current, as determined by the transistor manufacturer.

Leakoff

Fluid that escapes from the stuffing box of a centrifugal pump

Lean Gas / Dry Gas

A gas which is made up of primarily light hydrocarbon vapors.

Lean Oil

A special oil used in gas processing prior to containing NGLs.

Lean Oil Absorption

A method of removing NGLs from a gas stream whereby lean oil is flowed in a column countercurrent to a gas stream, absorbing the NGLs. The NGLs are then distilled out of the lean oil, which is recycled.

Lean amine

An amine solution that does not contain acid gases (hydrogen sulfide or CO2).

Learning Management System (LMS)

A software application for the administration, documentation, tracking, reporting, automation, and delivery of learning and development programs.

Learning Plan

See, Competency Development Plan

Learning Resource

Any form of training used to close a skill gap. Depending on the Job Level Required, learning resources may include self-study, e-Learning, instructor-led training, on-the-job training, attendance at an industry conference or seminar, etc.

Lease

A legal document executed between a mineral owner and a company or individual that conveys the right to explore for and develop hydrocarbons and/or other products for a specified period of time over a given area.

Lease Allowable

The volume of oil which can be produced from a lease during a given time period.

Leeward Side

The side that faces away from the wind.

Leg

The part of a length of conduit that does not change direction when a stub bend is made

Legend

An information guide or chart that identifies and explains the symbols, abbreviations, designations, and special marks used on a drawing, diagram, or set of diagrams.

Length

A single piece of conduit

Lesion

An injury, hurt or wound.

Level

A surface or an object that is determined to be perfectly horizontal. Also, a tool used to determine if an object is level

Level Control Diagram

A drawing that shows the level points at which various controls are activated.

Level Control Valve

A valve that controls the level in a system component by regulating the flow of a fluid

Lever Action

A bar or rod pivoting on a support. The effect of any force applied to the bar or rod is directly related to the distance between the force and its distance from the pivot.

Life Cycle Analysis (LCA)

LCA is an analytical methodology used to comprehensively quantify and interpret the environmental flows to and from the environment (including air emissions, water effluents, solid waste and the consumption/ depletion of energy and other resources) over the life cycle of a product or process. LCAs should be performed in adherence to the International Organization for Standardization (ISO) 14040 series of standards.

Lifeline

A flexible line that may be connected to an anchorage at one end to hang vertically or at both ends to hang horizontally used to allow a worker mobility while providing fall arrest protection.

Lift

The distance that a valve disc moves from the fully closed position to the fully open position. Also called travel.

Lift Check Valve

A type of check valve in which the disc is lifted to allow fluid flow through the valve

Lifting beam

A rigging component that is used to help balance a load by increasing the number of lifting points, or "pick' points, from one to two or more

Lifting capacity

The amount of weight that a forklift can lift and carry safely.

Lifting lug

A type of lifting connector that is commonly attached to a piece of equipment to ensure that the equipment will be safely supported and balanced when its lifted

Light Hydrocarbons

The components of a hydrocarbon mixture with five or less carbon atoms.

Light Hydrocarbons / Light Ends

The components of a hydrocarbon stream that have the lowest boiling points and viscosities.

Light cycle oil

A sidestream product of the fractionation process commonly used as a blending stock for No. 2 domestic heating oil and diesel fuels.

Light emitting diode (LED)

A type of diode that gives off light when current flows through it.

Light ends recovery unit

See Gas plant.

Light sensitive diode

A type of diode doped with materials that are light sensitive, giving the diode the characteristic of being able to use light to produce a voltage.

Light-off

The process of starting combustion in a boiler

Likeness

Likeness is a measure of the similarity of the dipmeter raw data curves.

Limestone

A sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate.

Limestone Matrix for Neutron Porosity

Limestone matrix for a neutron porosity log means that the neutron porosity tool is calibrated to read the correct porosity assuming that the pores are filled with fresh water and for a matrix of limestone.

Limit Switch

A pilot device that operates when a mechanical mechanism reaches its limit of travel, activated by physical contact with a part or material. Often used to stop a motor operator when a valve reaches its fully open or fully closed position.

Line Current

The current that flows through the wires in a three-phase system

Line Trap

A filter that prevents incoming transfer trip signals from passing through a substation; also called a wave trap

Line Voltage

The voltage that is applied to the wires in a three-phase system

Line current or voltage

The value of current or voltage in the generator leads that are attached to an electrical load.

Line of action

An imaginary line starting at an object's center of gravity that represents the force from the object as a result of gravity.

Linear Scale

A scale with divisions that have the same value from one end of the scale to the other

Link Layer

The network protocol level that governs how data bit frames are enclosed in message packets, how the transmitting and receiving clocks are synchronized, and how errors are detected

Link Light

The light on a network device that remains illuminated continuously whenever the device is connected to the network and the network is functioning properly

Liquefied natural gas (LNG)

Natural gas that has been converted to a liquid by refrigerating it to -260°F. Liquefying natural gas reduces the fuel's volume by 600 times, enabling it to be shipped economically from distant producing areas to markets.

Liquefied petroleum gas (LPG)

A product from a gas plant that typically consists of propane and butane.

Liquid

A fluid which conforms to the shape of its container, but cannot be compressed.

Liquid Asphalts

Straight-run asphalts that have been mixed with lighter distillates, oily distillates, or chemically treated water.

Liquid Ring Pump

A type of rotary vacuum pump that is often used in condenser air removal systems

Liquid Seal

Level of glycol which forces gas to pass through the bubble caps.

Liquid extraction

The removal of a substance that is dissolved in a liquid by transferring it to another liquid.

Liquid pressure

Force exerted against an object, such as a tank, caused by the weight of a liquid.

Liquid-Level Control

A device which senses the liquid level in a separator and opens or closes the liquid-level control valve.

Liquid-Level Control Valve

The valve which opens or closes to maintain design liquid levels.

Liquid-liquid sweetening system

A type of mercaptan conversion system in which the catalyst is dispersed in a caustic solution.

Lithics, Lithic Fragments

Pieces of other rocks that have been eroded down to sand size and now are sand grains in a sedimentary rock.

Lithification

Lithification is the geological process by which unconsolidated sediments (like sand, mud, and silt) compact under pressure, expel connate fluids, and gradually become solid rock.

Lithified, Lithification

The process in which sediments compact under pressure, expel connate fluids, and gradually become solid rock. Essentially a process of porosity destruction through compaction and cementation, lithification includes all the processes that convert unconsolidated sediments into sedimentary rocks.

Lithodensity Log

A lithodensity log is a variation of the density log which uses the photoelectric effect to indicate the formation's lithology.

Lithofacies

A lithofacies is a mappable subdivision of a designated stratigraphic unit, distinguished from adjacent subdivisions on the basis of lithology.

Lithology

The study of the general physical characteristics of rocks, including color, texture, grain size, mineral content, and composition. Can refer to the characteristics of rocks in a particular area.

Lithology, Lithological

The macroscopic nature of the mineral content, grain size, texture, and color of rocks.

Littoral

Littoral refers to the placement of items related to, or situated near, the shore of a sea or lake.

Load

A piece of equipment or circuit that uses electricity and creates a demand for electric power. Also, the demand on a system typically provided by the components that carry out the system's specific task.

Load Center

The point on which a load can be balanced and not tip; specifically, the horizontal distance from the vertical face of the forks on a forklift to the center of gravity of a load when placed directly against the forks.

Load Dispatcher

The individual who monitors the condition of a power system and coordinates the outputs of the plants in the system so that supply equals demand

Load leveler

A device used to make fairly large adjustments in the lengths of the sling legs in a hitch pattern.

Load resistor

A resistor in a transistor circuit used to develop an output signal.

Loader/Terminal

A hardware device, generally a PC, used to communicate with and program a PLC

Lobe Pump

A rotary positive displacement pump that uses lobed rotors to move fluid.

Local Area Network (LAN)

A geographically limited network that is sometimes used to replace the individual wires used in traditional, non-networked control systems

Local Display Module

A field communicator mounted on a field device that displays instrument data and can be used for calibration, configuration, and testing of the field device

Local Rack

The logical rack in a PLC system chassis that has the PLC processor in it

Local Rack or Chassis

The first rack of I/O modules in a PLC system. It usually contains the processor module, and it may contain one or more logical racks.

Location Specific Competencies

Competencies that are related to country- or-site specific requirements.

Locknut

A type of fitting used to secure threaded conduit or threaded connectors to a surface such as the wall of an electrical control box

Lockout

A procedure that uses locks or similar devices to actively prevent the passage of hazardous energy from a source to equipment that is being worked on.

Lockout Contacts

Contacts in a reclosing relay that turn the motor off with the relay in the "lockout" position

Lockout Contracts

Contacts in a reclosing relay that turn the motor off with the relay in the "lockout" position.

Lockout/tagout

Placing a lock, or a device like a lock, and a tag on an energy isolating device in accordance with established procedures that ensure the energy isolating device and the equipment being controlled cannot be operated until the lock is removed.

Log

A general term for a measurement versus depth or time, or both, of one or more physical quantities in and around a well. Operations in oil and gas exploration and production use a variety of log types.

Log Curve, Curve

A series of individual log measurements plotted versus depth or time, or both.

Log On/Log Off

The process of typing in your identification, and often a password, in order to access a computer or its programs; to log off, a set sequence of keystrokes or actions is often required

Log-Inject-Log Process

In the log-inject-log process, a pulsed neutron capture log is run over a zone of interest to establish a baseline reading. Subsequently, a brine of contrasting salinity is injected into the formation while logging successive passes with the pulsed neutron capture logging tool.

Logging Head, Head

The logging head is the wireline cable and logging tool attachment mechanism.

Logging Run, Logging Survey Run

Part of a service provided by a wireline logging company for a well operator client. To minimize rig time, several different logging tools are usually combined on the same tool string for each run into the borehole.

Logging Suite, Suite

A number of wireline logging runs acquired in succession within the same activity stage, such as at a casing point.

Logging Survey

A logging survey is a service provided by a logging service company for a well operator client. During the course of the survey, the logger usually uses several different logging tools.

Logging Tool

A logging tool is the downhole hardware needed to make a log.

Logging While Drilling (LWD)

The measurement of formation properties during the drilling of the hole through the use of tools integrated into the bottom hole assembly.

Logging, Well Logging

The measurement of formation properties.

Logic

In digital logic circuitry, the expected outcome from a network of logic elements designed to perform a specific function. (See Logic function).

Logic Circuit

An electronic circuit used in computers to perform a logical operation on its two or more input signals. The six basic circuits are AND, NOT, NAND, OR, NOR, and exclusive OR, which can be combined into more complex circuits.

Logic Diagram

A diagram that illustrates the implementation of logic functions with logic symbols showing details of signal flow but not point-to-point wiring.

Logic Function

A definition of the relationships that hold together a set of input and output logic variables.

Logic Gate

A circuit made up of solid-state components that evaluates information and produces a logical output when certain input conditions are met.

Logic State

One of two possible abstract states (logic 1 or logic 0) that may be taken on by a logic (binary) variable.

Logic Symbol

The pictorial representation of a logic gate.

Logical AND

The Boolean equivalent of two switches in series

Logical NOT

The Boolean equivalent of a normally closed switch

Logical OR

The Boolean equivalent of two switches in parallel

Logical Operation

The implementation of a logic gate's function to determine the logical output resulting from a specific set of inputs.

Logical Operator

The sign between elements of a logical expression that indicates what logical operation is being executed. For example, the AND operator is • and the OR operator is +.

Longitudinal Dune

A longitudinal dune is an elongated dune, typically tens of meters high and ranging up to several hundred kilometers long, lying parallel to the prevailing wind direction.

Longitudinal Relaxation Time

Longitudinal Relaxation Time (T1) in NMR logging is an indication of how fast the tipped protons in the fluids relax longitudinally, relative to the axis of the static magnetic field.

Loop

A complete electrical circuit or current path

Loop Gain

The combination of controller gain and process gain; the relationship between a change in a measured variable and the effect that the resulting control action has on that variable.

Loose Emulsion

An emulsion which is easy to break.

Lost Circulation

The total or partial loss of drilling fluids to high-permeability zones, cavernous formations, and natural or induced fractures during drilling or completion. It is the reduced or complete absence of fluid flow up the annulus when fluid is being pumped through the drill string, caused when drilling fluid exceeds the fracture pressure or invades the pore space of the formation.

Louver

A component in a fan system that covers the air intake and allows air to flow into the fan while helping to keep out trash and rain.

Low Contrast Pay

Low contrast pay entails a lack of a resistivity contrast between pay sands and the adjacent shales and water-bearing zones.

Low Limiter

A control device in which the output tracks the input but only down to a certain input level; the input may go lower, but the output cannot

Low Resistivity Pay

Low resistivity pay is characterized by pay zones that cause deep resistivity logs to read between 0.5 and 5 ohm-m.

Low Voltage (LV) Relay

An electromagnetic switch that stops a motor when voltage drops below a present value

Low Voltage Protection (LVP)

A form of protection against low voltage in which a motor controller stops a motor and prevents the motor from restarting on its own when voltage returns to normal

Low Voltage Release (LVR)

A form of protection against low voltage in which a motor controller stops a motor, but enables the motor to restart automatically when voltage returns to normal

Low pressure side

The part of a refrigeration cycle from the outlet side of the expansion valve to the suction of the compressor.

Low pressure tank

A tank that is capable of handling pressures from 0.5 psig to 15 psig.

Low-Pass Filter

A low-pass filter passes low-frequency signals, but reduces the amplitude of signals with frequencies higher than the cutoff frequency.

Low-impedance Grounding System

An intentional low resistance path for current flow to earth, or ground

Low-level output voltage

The smallest positive op-amp output voltage for the bias conditions applied to the power pins.

Lower explosive limit (LEL)

The minimum concentration of a flammable vapor or gas in air below which a flame will not be created in the presence of an ignition source, usually expressed as a percentage by volume.

Lowest Common Denominator (LCD)

The smallest whole number into which each of the denominators of two or more fractions can divide evenly

Lube Oil Cooler

A type of heat exchanger that maintains proper lube oil temperature

Lubrication

The reduction of friction by using a substance such as oil or grease between two rubbing surfaces.

Lug

A projection on the surface of a gear that transfers rotation from one component to another

Lumbar region

The lower region of the back, consisting of the five largest vertebrae in the spine.

Lung hazards

Chemicals that irritate or damage the pulmonary tissues

Lymph nodes

Any of the gland-like masses of tissue in the lymph system containing cells that become lymphocytes. Lymphocytes function in the development of immunity.

lag time

Lag time is the difference between the time a cutting is produced (by the drill bit acting against the formation) and the time it reaches the surface (shale shaker), carried there by the circulating drilling mud.

lapouts

A lapout is a stratal discontinuity that separates sedimentary units that are conformable from those that are non-conformable. Lapouts are also known as seismic reflection terminations and are used to identify depositional sequences and system tracts.

light output

The light output of a detector is the amount of photons produced by the detector per kiloelectron volt (keV) of energy deposited. Its unit is photons/keV. The light output of a detector is one of the most important parameters, as it affects the detector's efficiency and energy resolution

line ties

A line tie is where two seismic lines intersect.

lineations

Lineation refers to a repeated, parallel alignment of linear elements in a rock. These can be found in igneous, sedimentary, and metamorphic rocks,

lithological log

A lithological log is an annotated, graphical description of the formation rock characteristics encountered while drilling a well. The log is produced while the well is being drilled.

loops

A seismic loop is a continuous reflection pattern on a seismic profile.