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N

n

The saturation exponent in the relation between resistivity index and water saturation, typically about 2.

N-P-N transistor

A bi-polar transistor that contains two N-type elements (poles) and one P-type element.

N-type material

A semiconductor material that has an excess of electrons.

NACE

NACE International: the corrosion-control body whose standards govern material selection for sour service.

nacl

Sodium chloride, the salt whose concentration is measured in formation water and mud.

naesb

The body whose standard contracts and data formats underpin North American gas and power trading.

nameplate

A plate mounted on a piece of equipment that contains detailed information about that piece of equipment.

NAND gate

A digital logic gate that produces a LOW output only if both inputs are HIGH. If one or both inputs are LOW, the output is HIGH. It expresses the inverted output of an AND gate.

nanodarcy

A unit of permeability equal to 10⁻⁹ darcy.

nanometer

One billionth of a meter, the unit light wavelength is expressed in.

nanosecond

A unit of time equivalent to 0.000000001 seconds.

naoh

Sodium hydroxide, added to raise pH in drilling and treating fluids.

naphtha

A gasoline-range product of crude oil distillation that consists of hydrocarbon molecules.

naphtha fraction

The fraction whose carbon atoms range from C13 to C19, and have boiling points between 220°F and 315°F.

naphthene

A hydrocarbon with single-bonded carbon atoms in a circular arrangement; a component of naphtha.

naphthene-base crude oil

Crude rich in cycloalkanes and asphaltic material, with little or no paraffin wax.

naphthenes

Saturated ring hydrocarbons, the preferred feed for catalytic reforming.

naphthenic hydrocarbon

A saturated hydrocarbon whose carbons form one or more rings, also called a cycloalkane.

nappe

A large rock sheet thrust far over adjacent rock.

narrative learning

Teaching through story, which aids recall and makes context explicit.

narrow-azimuth seismic data

Conventional marine data from one vessel towing its sources ahead of the streamers, so all offsets lie close to the sail line.

NASBITE

The body awarding the Certified Global Business Professional credential.

national electrical manufacturers association (NEMA)

An organization that acts to maintain and improve the quality and reliability of electrical products.

national fire protection assoc. (NFPA) system

A labeling system that uses color coded sections to rate the flammability, reactivity, and health risks of a hazardous chemical with regard to fire prevention. These labels also include warnings about special hazards that are associated with the chemical.

national fire protection association (NFPA)

The organization that publishes the NEC and develops standards to minimize the possibility and effects of fire.

national fire protection association (NFPA) system

A hazardous material labeling system that uses color-coded diamond sections to rate the flammability, reactivity, and health risks of a hazardous substance. The labels are meant for use by emergency response personnel and not for the normal handling of the hazardous material.

national workforce

The host-country nationals an operator commits to employ, train and promote.

nationalization

A state taking ownership of petroleum assets previously held by private companies.

nationally recognized testing laboratories (NRTL)

An organization responsible for testing and certifying electrical equipment for safety.

native clay

Clay picked up from the formations being drilled rather than added deliberately as a commercial product.

native state core

A core taken so as to preserve the in-situ water saturation of the rock.

native-solids mud

A mud whose solids come from the formations being drilled rather than from added commercial products.

natural ciculation

A method of circulating water through a water tube boiler that depends on the differences in density between hot water, cold water, and steam.

natural circulation

The process by which water and steam move through some drum-type boilers; based on the fact that cold water is heavier than hot water or steam.

natural completion

A completion relying on the reservoir's own deliverability, with no stimulation and no artificial lift.

natural convection

Convection heat transfer that is the result of different densities within a fluid.

natural draft furnace

A furnace in which the energy required to move the air and combustion gases through the furnace is produced by a difference in density, without the aid of mechanical devices.

natural fracture

A break in the rock formed by geological processes rather than by drilling or stimulation.

natural fractures

Naturally occurring, non-sedimentary mechanical discontinuities thought to represent a surface or zone of mechanical failure.

natural frequency

The frequency at which a system oscillates freely once disturbed, with no driving force applied.

natural gamma ray

The formation's own radioactivity, logged to distinguish shale from clean rock.

natural gamma ray log, gamma ray log

A natural gamma ray log is a measurement of the natural emission of gamma rays by a formation.

natural gamma ray spectroscopy

A log measuring not just the total natural gamma ray count but its energy spectrum, resolving the contributions of potassium, uranium and thorium.

natural gamma ray spectroscopy, gamma ray spectroscopy, spectroscopy

Natural gamma ray spectroscopy is the technique of measuring the spectrum, or number and energy, of gamma rays emitted as natural radioactivity by the formation.

natural gas

A highly compressible, highly expandable mixture of hydrocarbons occurring naturally in gaseous form, whose principal component is usually methane. It exists either in the gaseous phase or dissolved in crude oil in natural underground reservoirs. It may also contain nonhydrocarbon gases such as carbon dioxide and hydrogen sulfide.

natural gas liquids

Those components of natural gas which under suitable conditions of temperature and pressure are in the liquid state.

natural gas liquids (NGLs)

Those components of natural gas which, under suitable conditions of temperature and pressure, are in the liquid state. A general term for highly volatile liquid products separated from natural gas in a gas processing plant, including ethane, propane, butane, and condensate.

natural gas measurement

The metering of gas volume and energy content on which payment depends.

natural gas pipeline

The pipe system transporting gas between production, processing and market.

natural gasoline

The heaviest natural gas liquid fraction, stable enough to store at atmospheric pressure.

natural remanent

The magnetization a rock retained from when it formed.

natural remanent magnetism

The magnetization a rock carries from fields it experienced in the past, before any laboratory treatment.

natural-draft cooling tower

A cooling tower in which air flows through the tower because of a difference in air density.

naturally flowing well

A well whose reservoir pressure is enough to lift its fluids to surface at a commercial rate without artificial lift.

naturally fractured reservoir

Reservoir where pre-existing fractures dominate flow, giving high rates and rapid water breakthrough.

naturally occurring radioactive materials (NORM)

Radium and its decay products concentrated in barium and strontium scales deposited in tubing and surface equipment, abbreviated NORM.

nautical mile

A distance unit used in marine and air navigation, equal to 1.852 km.

navigation diagram

The programming structure of a smart controller, usually detailed in printed form in the controller's user manual. Also called a structure diagram.

NCDMB (Nigerian Content Development and Monitoring Board)

The board enforcing Nigeria's local content requirements on operators and contractors.

NDCs (Nationally Determined Contributions)

Each country's self-declared emissions pledge under the Paris Agreement.

near miss

An event that could have caused harm but did not, and the cheapest warning available.

near offset

A short source-receiver separation, giving near-normal incidence.

near water

Near water is the water bound to clays in the dual water model.

near-field

Near-field refers to the receivers (geophones or hydrophones) that are closest to the source.

near-surface correction

A time shift applied to seismic traces to remove the effect of the variable weathered layer and surface elevation.

near-wellbore

The rock immediately surrounding the hole, where damage and stimulation act.

near-wellbore permeability

The permeability immediately around the hole, altered by damage or stimulation.

nearshore

Moving activity to a nearby country, trading some cost saving for proximity and time zone.

neat cement

Cement mixed with water alone, carrying no additives to modify its setting time or rheology.

needle valve

A globe valve with a needle- or cone-shaped disc that fits deep into the seating area, designed for precise throttling control of flow with a two-90° turn flow pattern.

needs assessment

Establishing what problem is actually being solved before specifying anything.

negative feedback

See Feedback.

negative power

Power that is returning to a power source from a load.

negative pressure check

A check for leakage into a respirator when a negative pressure is created inside the respirator by inhaling.

negative pulse telemetry

Telemetry systems that create a pressure pulse lower than that of the mud volume by venting a small amount of high-pressure mud from the drill string to the annulus.

negotiable instrument

A document promising payment that can be transferred to another holder.

negotiating brief

The written mandate setting a team's objectives, limits and authority before it negotiates.

negotiation

Reaching agreement with someone whose interests differ from yours.

negotiation styles

Individual habits of negotiating, which persist unless deliberately varied.

NEMA

The National Electrical Manufacturers Association.

NEMA code K controller

A type of DC controller made standard by the National Electrical Manufacturers Association.

nephelometer

A turbidity meter.

nephelometric turbidity unit

A unit of measurement that is typically used to express turbidity. Abbreviated as NTU.

NEPL (NNPC Exploration and Production Limited)

NNPC's exploration and production subsidiary, holding its operated upstream interests.

neritic

Pertaining to the shallow marine zone from low tide out to the edge of the continental shelf.

neritic zone

The neritic zone is a shallow marine environment extending from mean low water down to 200-metre (660-foot) depths, generally corresponding to the continental shelf.

nested fractal structures

A model in which more than one property is described by fractal geometry, at more than one scale.

net acres

The percentage that a company owns in an acreage position with multiple owners. For example, a company that has a 50 percent interest in a lease covering 10,000 acres owns 5,000 net acres.

net exposure

What remains after purchase and sale positions offset each other.

net gas production

Gas produced less gas reinjected — the volume actually leaving the field.

net oil production

Oil produced less oil returned to the well, the volume actually available for sale.

net overburden pressure

The overburden stress less pore pressure, which is what the rock frame actually carries.

net pay

The reservoir quality thickness above the hydrocarbon contact, normally also including a designated cutoff for high water saturation.

net positive suction

The suction pressure margin above vapor pressure, without which a pump cavitates.

net positive suction head

The amount of suction head, or pressure, that exceeds the vapor pressure of the fluid that is being moved by a pump.

net present value (NPV)

The sum of discounted cash flows less the investment; positive means the project adds value.

net profits interest

A share of net proceeds from production, carved out of and paid from the working interest owner's share, abbreviated NPI.

Net Promoter Score (NPS)

A single question measuring willingness to recommend, used as a loyalty proxy.

net refining margin

Gross refining margin after deducting variable operating and energy costs.

net revenue interest

An owner's share of production after royalty and any other burdens have been deducted from the working interest.

net sand

The reservoir quality thickness of a rock unit after the non-reservoir rock is eliminated from an evaluation.

net sand count

The net sand count is the total effective thickness of a reservoir-quality permeable section of the reservoir, excluding shale streaks and other impermeable, low-porosity zones.

net sand thickness

Net sand thickness is the thickness of reservoir quality layers between the oil-water contact and the top of the reservoir.

net-zero by 2050

The target of balancing residual emissions with removals by mid-century.

net-zero emission

Emissions balanced by removals, so the atmospheric total does not rise.

net/gross pay

Net/Gross pay is the net pay divided by the gross pay. Pay is the component of a reservoir that contains economically producible hydrocarbons.

net/gross sand

Net/Gross sand is the net sand divided by the gross sand.

netback

Realized value at a reference point after subtracting transport and processing costs.

netback pricing

Pricing derived from the value at the market less the cost of getting there.

network

A system of interconnected devices that allows communication of digital data between them. Individual pieces (nodes) may be devices, parts of a PLC system, or complete PLC systems.

network adapter

The interface between a network and any device connected to the network; converts data from the network to a form that the device can read, and converts data from the device to a form that is compatible with the network.

network analyzer

A device that monitors all connected networks and provides information about network resource utilization and network activity.

network attack

An attack directed at network infrastructure or traffic rather than at an endpoint.

network layer

The network protocol level that governs functions that have to do with how message packets are initiated, addressed, and routed without collisions.

network protocol

The rules that govern or define how data is transmitted across a network.

network topology

The physical layout of network.

networking plan

A deliberate approach to whom to meet and why, rather than attending events at random.

neural network

A computational model of interconnected weighted nodes that learns relationships in data rather than being programmed with them.

neutral flame

An oxy-fuel gas welding torch flame that burns equal parts of oxygen and acetylene. Characterized by a light blue inner cone and a dark blue outer flame envelope.

neutral point

The point in a string of tubulars at which axial load passes through zero, with tension above and compression below.

neutral position

A position that requires the least amount of muscle activity to maintain. For example, when a person's arm is hanging straight down with the elbow close to the body, the shoulder is said to be in a neutral position.

neutral transformer

A device used with some wye-connected AC generators that detects and limits current flow to ground if a ground occurs in the generator.

neutralization

A chemical reaction in which an acid reacts with a base to form water and a salt.

neutralization reaction

A chemical reaction between an acid and an alkali that consumes the acid and the alkali and tends to make the solution neutral.

neutralize

To react an acid with a base so that a salt and water are formed and the corrosive activity is removed.

neutralizing

Bringing pH toward neutral so a fluid stops attacking metal.

neutralizing solution

A fluid, typically alkaline, pumped to counteract the corrosive effect of an acid treatment before the well is returned to service.

neutron

A subatomic particle with no net electric charge and a mass slightly larger than that of a proton. Together with protons, neutrons constitute the nucleus of an atom.

neutron activation

Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus often decays immediately by emitting gamma rays, or particles such as beta particles and alpha particles.

neutron activation log

A log of elemental concentrations from the gamma rays emitted by nuclei made radioactive by neutron bombardment.

neutron capture

A type of nuclear reaction in which a target nucleus absorbs a neutron, then emits a discrete quantity of electromagnetic energy (gamma ray photon), merging to form a heavier nucleus.

neutron capture log

A log measuring how readily the formation captures neutrons, which responds to chlorine and so to salt water.

neutron flux

The neutron flux is a scalar quantity used in nuclear physics and nuclear reactor physics. It is the total length travelled by all free neutrons per unit time and volume.

neutron generator

A miniature charged-particle accelerator that produces bursts of high-energy neutrons on command, in place of a chemical neutron source.

neutron generator, neutron accelerator

Neutron generators are neutron source devices which contain compact linear particle accelerators and that produce neutrons by fusing isotopes of hydrogen together.

neutron interactions

The ways a neutron transfers energy to a nucleus it encounters — elastic scattering, inelastic scattering and capture.

neutron lifetime log

A neutron lifetime log is a pulsed neutron capture log.

neutron log

A porosity log responding chiefly to the hydrogen present in the formation, and usually synonymous with the neutron porosity log.

neutron log, compensated neutron log, neutron tool

The compensated neutron log tool makes thermal and epithermal neutron measurements to calculate porosity and identify lithology and the presence of gas.

neutron porosity

A measurement based on the slowing down of neutrons between a source and one or more detectors that measure neutrons at the epithermal level, where their energy is above that of the surrounding matter, between approximately 0.4 and 10 eV.

neutron porosity log

A porosity log responding to hydrogen content, and therefore to gas as an apparent deficit.

neutron porosity tool

The tool measuring hydrogen content to infer porosity.

new product development

The process from concept through design and testing to launch.

new venture

A newly formed business, not yet established in its market.

newbuilding

A vessel under construction or newly delivered from the yard.

Newtonian fluid

A fluid whose shear stress is directly proportional to shear rate, so viscosity changes only with temperature and pressure.

A circuit tester readout that indicates Near End Crosstalk.

NGL

Natural gas liquids. Refers to the mixture ofhydrocarbon components that are recovered from a natural gas stream during gas processing.

ngl flow

The natural gas liquids rate through a unit.

ngl measurement

Measuring natural gas liquids, complicated because they are liquid only under pressure.

ngl pipeline

A pipeline carrying mixed natural gas liquids to a fractionation plant.

ngl sample

A pressurized sample of natural gas liquids, which must stay liquid to remain representative.

ngl sampling

Taking a representative sample of natural gas liquids without letting it flash.

ngl storage bullet

A horizontal pressure vessel holding natural gas liquids, so named for its shape.

ngl stream

The natural gas liquids flow recovered from gas.

Nigerian Content

The Nigerian goods, services and personnel a project is required to use.

Nigerian Petroleum Industry Board Game

The onboarding exercise teaching how Nigeria's petroleum sector and its regulation fit together.

nine key EI factors

The component abilities the course uses to break emotional intelligence into things one can practice.

nine key qualities for leadership

The attributes the course identifies as consistently present in effective leaders.

nipple

A short heavy-walled tubing section machined internally with a seal bore and locking profile, so tools can be landed and sealed at a known depth.

nipple down

To dismantle the blowout preventer stack or wellhead equipment at the end of an operation.

nipple up

To assemble and connect equipment, particularly to install and make up the blowout preventer stack on the wellhead.

nitrified fluid

A treatment fluid into which nitrogen gas has been mixed, giving a lighter two-phase fluid that flows back under its own energy.

nitrogen cushion

A column of pressurized nitrogen placed in the test string so the formation is not opened to an empty pipe.

nitrogen injection

Injection of nitrogen gas into a reservoir to maintain pressure and displace oil, usually at high pressure to approach miscibility.

nitrogen kickoff

Circulating nitrogen into the production conduit to lighten the fluid column and start a well flowing.

nitrogen lift

Circulating nitrogen into the well to lighten the fluid column so the reservoir can flow.

nitrogen lifting

The operation of injecting nitrogen to unload a well and bring it on to production.

nitrogen oxide

An oxide of nitrogen formed at flame temperature, regulated and reduced by lowering peak temperature.

nitrogen oxides

The products formed when nitrogen combines with oxygen. When released to the environment, they create a form of air pollution.

nitrogen unit

The surface package that supplies high-purity nitrogen at pressure, either from liquid nitrogen or by separating it from air on site.

NMDPRA (Nigerian Midstream and Downstream Petroleum Regulatory Authority)

Nigeria's midstream and downstream regulator, covering processing, transport and marketing.

NMO

Normal moveout: the extra traveltime a reflection takes as source-receiver offset increases over a flat reflector, removed before the traces are stacked.

nmo correction

Removing the offset-dependent travel time difference before seismic traces are stacked.

NMR

Nuclear magnetic resonance: a log measuring the response of formation hydrogen to a magnetic field, giving porosity independent of lithology.

NNPC Limited

Nigeria's national oil company, reconstituted under the Act as a commercial company.

no-go landing nipple

A landing nipple with a restricted bore below its profile, so a tool cannot pass beyond the point at which it should land.

NOC (National Oil Company)

A state-owned oil company holding its country's resources and answerable to government rather than shareholders.

NODAL analysis

Splitting the production system at a chosen node and matching inflow to outflow there, to forecast how the whole system will perform.

node

A device on a network.

noise

Extraneous signal variations or unwanted sounds that do not represent the intended information. In process control, it refers to input quantities unrelated to actual process conditions. The common-mode rejection characteristic of op amps can be used to cancel noise external to a circuit.

noise figure

The ratio of the total noise power at the output of an amplifier, referred to the input, to the noise power of the signal source.

noise log

A record of the sound generated at successive depths in a well, used to locate flow behind pipe, leaks and channels.

noise reduction rating (NRR)

A measure of the approximate number of decibels that a hearing protection device attenuates, or reduces.

nominal filter

A filter rated to remove most, but not a guaranteed proportion, of particles above a stated size.

nominal size

The approximate diameter of a bolt or screw.

nomograph

A graph that uses three or more different scales to represent the values of three or more variables that are related; also called an alignment chart.

non-adjustable orifice

A restriction, such as a section of tube or pipe, that is used as a simple means of flow control.

non-associated gas

Gas produced from a reservoir holding little or no oil.

non-bulk packaging

Hazardous materials packaging smaller than bulk packaging, with a capacity of 119 gallons or less for liquids, a net mass of 882 pounds or less and capacity of 119 gallons or less for solids, and a water capacity of 1,000 pounds or less for Class 2 gases. Includes containers such as boxes, tanks, and cylinders.

non-condensable gas

Gas that will not condense at the operating conditions, and which spoils a condenser's vacuum.

non-condensible gas

Gas that will not condense at the condenser's conditions, and which destroys vacuum if not removed.

non-Darcy flow

Flow at velocities high enough that inertial losses matter, so pressure drop rises faster than Darcy's law predicts.

non-insulated wire

A bare wire that is not covered with insulation.

non-inverting amplifier

An op amp circuit in which a signal is applied to the non-inverting input terminal.

non-inverting input terminal

The input terminal of an op amp represented by a positive (+).

non-linearity

A characteristic of process loops in which an input at one point does not produce the same output as that same input at another point; variations in process gain at different parts of a process variable's range.

non-newtonian

Having a viscosity that changes with shear rate, as drilling and fracturing fluids do.

non-Newtonian fluid

A fluid whose viscosity is not constant but changes with the shear rate applied to it.

non-numerical data

Qualitative information that must be categorized before it can be analyzed.

non-opec country

A producing country outside the exporting organization.

non-operated venture

A holding in which the company funds its share but another party operates.

non-operator

A joint-venture partner that funds its share of costs but does not run operations.

non-permit confined space

Means a confined space that does not contain or, with respect to atmospheric hazards, have the potential to contain any hazard capable of causing death or serious physical harm.

non-recourse debt

Debt lenders can recover only from the project, not from the parent company.

non-return valve

A valve allowing flow one way only.

non-return valves

Valves that operate like swing check valves to protect the turbine from possible back flow in case the flow of steam to the turbine stops.

non-selective azeotropic solvents

Solvents that form azeotropes with a variety of compounds and have a wide azeotropic range.

non-sheathed capacitance probe

A single capacitance probe that uses the walls of a container and the probe as the two plates of the "capacitor."

non-sinusoidal oscillator

An oscillator that produces a signal that is anything other than a sine wave.

non-stratabound

Does not terminate at geological strata.

non-volatile memory

A type of RAM that does not need power to retain its data.

non-working power

Voltage and current that does not perform work.

nonconductive drilling fluid

A mud whose continuous phase does not conduct, so SP and electrode resistivity logs cannot be run in it.

nonconformance

An event that results in a product that does not meet specifications.

nonconformity

An unconformity where sedimentary strata rest directly on eroded igneous or metamorphic basement.

noncontrolling interest

The share of a subsidiary that the parent does not own, shown separately in consolidated accounts.

noncurrent asset

An asset the business expects to hold for more than a year.

nondepositional hiatus

A nondepositional hiatus is often considered as the time value of an episode of nondeposition or of nondeposition and erosion together.

nondestructive examination (NDE)

Inspection that assesses a component's condition without impairing its structure or function, abbreviated NDE.

nondipole field

The part of the Earth's main magnetic field left after the best-fitting dipole is removed.

nonhydrocarbon

A component that is not a hydrocarbon, such as nitrogen, carbon dioxide or hydrogen sulfide.

nonhydrocarbon contaminants

The non-hydrocarbon components produced with oil and gas — hydrogen sulfide, carbon dioxide, nitrogen and water.

nonideal gas

A gas whose behavior requires the compressibility factor z in the equation of state, pV = znRT.

nonlinear scale

A scale with divisions that do not have the same value from one end of the scale to the other.

nonlinear sweep

A vibrator sweep whose frequency changes at a varying rate, shaping the output spectrum.

nonmarine

Deposited on land rather than in the sea.

nonparticipating royalty

A share of production or its value, free of drilling and production costs, held by a party with no say in operations.

nonparticipating royalty interest

An ownership share of production paid to a holder who has no right to explore, develop or lease, abbreviated NPRI.

nonprofit fundraising

Raising money for an organization that does not distribute profit.

nonrising stem

A gate valve stem threaded into the gate itself, so the gate travels while the stem stays at the same height.

nonverbal cue

Any signal conveyed without words, often contradicting what is said.

NOR gate

A digital logic gate that produces a HIGH output only if both inputs are LOW. If one or both inputs are HIGH, the output is LOW. It is the inverted output of an OR gate.

normal

A conventional resistivity device in which the current electrode and the measure electrode sit close together on the sonde.

normal alkane

A straight-chain saturated hydrocarbon, whose distribution in an oil identifies its source and maturity.

normal butane

The fourth lightest hydrocarbon molecule (C4H10), a by-product of conversion processes from various units. Often sold mixed with propane as fuel (LPG mix), added to gasoline, or used as a petrochemical feedstock.

normal distribution

The symmetric bell-shaped distribution many statistical methods assume.

normal fault

A normal fault is a geologic fault in which the hanging wall has moved downward relative to the footwall. Normal faults occur where two blocks of rock are pulled apart, as by tension or extension of a basin.

normal faulting

Extensional faulting where the hanging wall drops, typical of rifts and passive margins.

normal incidence

The case where a wave strikes an interface square on, its raypath perpendicular to the boundary.

normal mode

Acoustic energy that travels along the borehole while being trapped across it by the borehole wall.

normal moveout

The increase in reflection traveltime with source-receiver offset for a flat reflector, abbreviated NMO.

normal pressure

Pore pressure equal to the hydrostatic head of a column of formation water extending to surface.

normal winter

The average gas demand the LDC is expecting to satisfy daily on any year; it is lower than the Design Winter.

normal-moveout correction

The time shift applied trace by trace to remove normal moveout, so a reflection aligns flat across the gather before stacking.

normality

A concentration unit giving the number of equivalent masses of solute dissolved in each liter of solution, symbol N.

normalization

Adjusting measurements to a common basis so they can be compared.

normally closed

A switch or set of contacts that allows current to flow through it when it is not activated (when nothing depresses its actuator). Abbreviated NC.

normally closed, held open

A switch that allows current to flow through it when it is not activated, but that is held activated by some mechanism. Abbreviated NCHO.

normally open

A switch or set of contacts that does not allow current to flow through it when it is not activated (when nothing depresses its actuator). Abbreviated NO.

normally open, held closed

A switch that does not allow current to flow through it when it is not activated, but that is held activated by some mechanism. Abbreviated NOHC.

normally pressured formation

A formation with pore pressure, proportional to depth, that is roughly equal to the hydrostatic pressure gradient of a column of salt water (0.465 psi/ft).

norms and customs

The unwritten rules people actually follow.

north arrow

An arrow, which points due north, that is included on a blueprint to help orient the drawing.

north pole

The northernmost point of the Earth's axis.

North Sea crude markets

The Brent, Forties, Oseberg, Ekofisk and Troll cargo trade that underpins Dated Brent.

NOT gate

A digital logic gate that inverts its input: it produces a HIGH output (1) when the input is LOW (0), and a LOW output when the input is HIGH.

notes

In electrical diagrams, a section that gives detailed information about certain parts and may list other references. In the NEC, details that typically follow tables to provide clarification or additional information.

nozzle

A device connected to a hose or pipe to direct and control the flow of fluid. In jet pumps, the part that performs energy conversions to create flow in a fluid system.

NP chart

An attribute control chart that is used to plot the number of defective products that are produced by a process.

NPDES

National Pollutant Discharge Elimination System: the US permitting regime, under the Clean Water Act, controlling discharges to surface water.

nrel

The United States National Renewable Energy Laboratory, whose cost and performance data these courses cite.

NRM

Natural remanent magnetization: the magnetization a rock carries as sampled in the field, before any laboratory treatment.

NRU

"Nitrogen Rejection Unit" used to remove nitrogen from the gas stream for injection into oil reservoirs to enhance oil recovery. Applies cryogenic principles.

nuclear fluid densimeter

A production logging sensor that infers wellbore fluid density from the attenuation of gamma rays between a source and a detector.

nuclear magnetic relaxation

Nuclear magnetic relaxation is the processes by which an excited magnetic state returns to its equilibrium distribution. Nuclear magnetic resonance relaxation measurement can be used for spectral assignment and the study of quadrupolar and paramagnetic interactions, and exchange dynamics.

nuclear magnetic resonance

A phenomenon in which a nucleus absorbs electromagnetic radiation of a specific frequency in the presence of a strong magnetic field.

nuclear magnetic resonance (NMR) physics

Atomic nuclei spin, and this angular moment produces a weak magnetic field. The NMR technique measures the magnetic signal emitted by spinning hydrogen nuclei protons as they return to their original state following stimulation by an applied magnetic field and pulsed radio frequency energy.

nuclear magnetic resonance logging

Nuclear magnetic resonance (NMR) logging uses the NMR response of a formation to directly determine its porosity and permeability, providing a continuous record along the length of the borehole.

nuclear magnetic resonance measurement

A measurement of hydrogen nuclei's response to a magnetic field and radio pulses, giving porosity and pore size distribution.

nuclear magnetic resonance signals

Magnetic resonance imaging uses the movement of protons within a magnetic field to generate an image. The number of nuclear magnetic resonance signals represents the number of different types of protons in a molecule.

nuclear plant

A power plant that uses energy from fission to produce electric power.

nucleation

The stage of crystallization in which small crystals, or nuclei, are formed.

nucleus

The positively charged, very dense central core of an atom, consisting of protons and neutrons and containing nearly all its mass. The atom as a whole is electrically neutral because the positive nucleus is surrounded by negatively charged electrons.

nucleus, atomic nucleus

The nucleus is the very dense region consisting of protons and neutrons at the center of an atom.

NUIMS (NNPC Upstream Investment Management Services)

The NNPC arm managing the state's interests in joint ventures and production sharing contracts.

number line

A line with marks, representing numbers, at equal distances form each other.

numerator

In a fraction, the number above the fraction bar, indicating how many parts are needed to express a measurement.

numerical methods

Techniques that solve equations by iterating on approximations rather than by evaluating a closed-form solution.

numerical model

A representation of a reservoir or field held entirely as numbers on a grid, solved by computation rather than by analytical formula.

numerical reservoir simulation

Numerical reservoir simulation is the mathematical simulation of a numerical model of a reservoir's petrophysical characteristics to analyze and predict fluid behavior in the reservoir over time.

numerical reservoir simulation model

A mathematical grid block model of a petroleum reservoir used to simulate and analyze historical fluid behavior and predict future performance, where each block represents a local part of the reservoir.

numerical reservoir simulator

The software that solves flow equations cell by cell across a gridded reservoir model.

numerical simulation, reservoir simulation

A numerical simulation is a calculation that is run on a computer following a program that implements a mathematical model for a physical system. Reservoir simulation is the process of constructing and running a model that mimics the appearance and flow dynamics of an actual reservoir system, including the subsurface porous and permeable reservoir and its other physical components to produce (wellbore) and process the reservoir fluids.