Top Energy Training


Absorber Unit

A unit that provides contact between the gas and the amine solvent so that H2S and CO2 can be transferred from the gas to the liquid phase.

Acid Job

The treatment of a reservoir formation with a stimulation fluid containing a reactive acid. In sandstone formation the matrix is used to enlarge pore spaces, while in carbonate formation the acid dissolves the formation matrix.

Active Fault

Fault currently producing or having recently produced displacement or slip


Organic compound composed of single bonded carbon and hydrogen atoms, usually with the formula CnH2n+2. Compounds where carbon atoms are joined by a single bond are called “saturated”. Alkanes are divided into three groups: linear straight chain alkanes also called normal alkanes, branched alkanes, and cycloalkane.

Amine Process

The process of removing hydrogen sulfide and carbon dioxide from gases.


A group of organic chemicals and functional groups that contain an N atoms with a lone pair (pair of valence electrons not shared with another atom) that are analogs of ammonia (NH3) in which 1-2 hydrogen atoms are replaced by organic radicals (highly reactive and short lived uncharged molecules).

Anime Process

The process of removing hydrogen sulfide and carbon dioxide from gases.

Anisotropic Stress

Forces that have directionally dependent properties.


Void between any layer of piping, tubing or casing and the next outer layer of piping, tubing, casing, or earth.


Areas of a basin or water way that depleted of dissolved oxygen. DO concentrations are less than 0.5 mg/L.


Structural folded rocks that formed as a result of compressional tectonic forces. The layers dip away from the center or axis of the fold. The oldest rock beds are in the center of the fold.


A rock unit containing water in its pore spaces.

Artesian Spring

A scource of water where groundwater flows freely to the surface because the aquifer is under pressure.

Balanced Drilling

When the forces acting on a drill string in an active wellbore are equal to the forces being exerted by the wellbore.

Band Brake

Slows the motion of the drawworks.


Mineral barium sulfate (BaSO4) used as a weighting agent for drilling fluids.

Bell Nipple

The bell nipple is a large diameter section of pipe found just above the blowout preventer. The drill string passes through it and into a smaller pipe up above.

Bentonite Clay

A material composed of clay minerals commonly used in drilling mud. Bentonite clay swells when it is exposed to water making it a good material to use to protect formations from invasion of drilling mud.

Biogenic Production

Natural gas formed near the surface of the Earth by the growth of microorganisms called methanogens. Methanogens produce methane as a metabolic byproduct.


Viscous, semi-solid mixture of hydrocarbons.


A fan used to lower concentration of gas in an area.


An uncontrolled release of pressure from the well.

Blowout Preventer

A large valve placed at the top of a well that may be closed if the drilling crew loses control of formation fluids. Closing allows the crew to regain control of the reservoir and retain pressure control of the formation.

Blowout Preventer – Annular Type

This blowout preventer consists of rubber “wedges” that can be extruded into the wellbore by hydraulic pistons. These wedges can create a powerful seal around drill-string pipes as well as irregularly shaped pipes like kellys.

Blowout Preventer – Blind Shear Ram

Shear ram BOPs are the most effective, but also the most destructive. They sever the drill string and seal off the entire wellbore regardless of its contents.

Blowout Preventer – Pipe Ram

The pipe ram BOP has two metal rams designed to close around the outside of a pipe of a certain size, preventing flow within the annulus while maintaining the integrity of the pipe and allowing flow within it.

Blowout Preventer – Ram Type

These BOPs consist of two rams that press together and seal off an empty borehole. They are unable to seal boreholes containing pipe.

Bottom Hole Assembly

The bottom portion of the drillstring. The bottom hole assembly in its simplest form includes the drill bit, crossovers, and drill collars.

Bulk Porosity

The percentage of the rock that is occupied by fluids as opposed to solid matter.


An adaptor used to connect the kelly to the rotary table, sometimes called a kelly bushing or a rotary bushing.


Impermeable layer of rock that seals any fluids, such as hydrocarbons or water, in the deeper rock layer beneath it.


Steel pipe lowered in an openhole and cemented in place to stabilize the wellbore. Casing must withstand forces at depth such as collapse, burst, tensile failure and chemically aggressive brines.

Casing Hanger

A flanged pipe that fits into the top of existing casing or the wellhead.

Chemical Sedimentary Rock

An inorganic sedimentary rock that forms from minerals that precipitate out of solution.

Christmas Tree

A series of valves and fittings mounted on the top of a well that together are designed to control the flow of hydrocarbons from the well.

Christmas Tree Choke

A device used to control the fluid flow rate.


Sedimentary rock composed of clasts, or fragments or grains of weathered rocks.


A fragment or grain that composes clastic rocks.

Claus Process

A complex multi-step process that breaks apart the sulfur and hydrogen that make up hydrogen sulfide.


A type of mudstone that contains at least 50% clay (grain size < 0.04 mm) by composition.

Compton Scattering

A gamma ray interaction in which a gamma ray collides with an electron, transferring part of its energy to the electron, while itself being scattered at a reduced energy.

Conductor Casing

A large diameter metal tube that is usually placed into the well first that extends to bedrock to prevent the well hole from caving in.

Cone Of Depression

A reduction in the pressure head near a well that is being pumped.


A coarse clastic sedimentary rock composed of gravel sized grains (>2mm) within a matrix of finer grains. The larger clasts of a conglomerate are rounded.

Core Barrel

A tube inside the drill pipe that is supported by a drill bit and collects a core sample.

Core Plugs

A sample or plug of rock taken from a core for analysis.

Core Samples

Long cylindrical pieces of rock removed from the borehole.

Coring While Drilling

Collection of a core boring while drilling the wellbore.

Correlative Rights

Legal principle that states that adjoining landowners must limit their use of a common water source.

Crown Block

The crown block is a fixed system of pulleys at the very top of the rig.

Darcy’s Law

The velocity of flow of a liquid through a porous medium due to differences in pressure that is proportional to the pressure gradient in the direction of flow.


A device that removes large solids from the drilling mud.


A device that removed small solids that a de-sander from the drilling mud.


The drilling line from the crown block to the anchor that does not move.

Delay Rental

Fees paid to the lessor to delay production or drilling without termination of the lease.

Depositional Environment

Locations where material or sediments are deposited, like a lake, river, or swamp. Sedimentary layers that accumulate in depositional environments have distinctive characteristics that provide geologists with information about the geologic history of an area. Depositional environments are broadly classified into: continental environments where deposition occurs on land or in fresh water, transitional environments where deposition occurs with the influence of both fresh water and salt water (the Chesapeake Bay, for example), and marine environments where sedimentation is only influenced by the oceans.

Depth Of Investigation

The distance into a rock formation a particular tool makes measurements.


The derrick is the tall structure that most people think of when they picture oil and gas drilling. It has two purposes: First, it supports the weight of the drillstring and associated equipment, which can weigh more than two million pounds. Second, it allows pipes to be hoisted completely out of the well in sections of up to around 100 feet.

Diamond Coring

Drilling that uses industrial grade diamonds to core solid rock.


These rigs still rely on diesel engines for power, but the engines are used to generate electricity, which is then transmitted to the rig systems, which have individual electric motors.


The machine on the rig that consists of a large diameter steep spool, brakes and a power source to reel out and reel in the drilling line.

Drill Collar

A thick walled piece of pipe usually made of steel that is placed between the drill pipe and the drill bit.

Drill String

The drillpipe, bottomhole assembly and any other tools to make the drill bit turn at the bottom of the wellbore.

Drilling Line

A line that is used to hoist or lower drilling pipe out of or into a wellbore.

Drilling Mud

Liquid and gaseous fluids and solids used in operations to drill boreholes.


Release of energy from the Earth’s lithosphere producing seismic waves and resulting in shaking at the surface

Electrical Resistivity

The ability of a mertial to resist the flow of an electrical current, measured in units ohm-m.


A chemical additive that causes an emulsion, which is the dispersion of one impersible liquid into another (like oil in water) by reducing the interfacial tension between the two liquids to achieve stability.

Enhanced Oil Recovery

Technique used to either change qualities of the hydrocarbon resource or qualities of the reservoir in order to extract more hydrocarbons

Enhanced Recovery Technique

Oil recovery method that uses methods to alter the chemical properties of the oil to make it easier to extract.


The point on Earth’s surface directly above the hypocenter.


Demonstration of moral competence, expertise and knowledge.


With respect to hydrocarbons, the process of finding oil and gas deposits deep below the Earth’s surface.


Sedimentary layers that are different in appearance or composition than adjacent sediments. A facies implies information pertaining to the ancient depositional environment.


Incorrect argument in logic and rhetoric.


Fracture in rock across which there has been movement of rock, also known as displacement.

Fire Flooding

A technique that allows reservoir engineers to cause a controlled underground oil fire, which serves to heat up the surrounding rocks and the oil contained in them.

Fish or Junk

Anything that is left in the wellbore.


Removal of unwanted material from the wellbore.


Fluids used to hydraulically fracture a formation that flow back to the surface during and immediately after the operation.

Flowback Fluid

The fluids that return to the surface after hydraulic fracturing treatment.

Fluid Transport Behavior Model

Creation of computer models that integrate geology and chemical reactions to estimate the transport of fluids through the Earth’s crust.


Bend or curve in sedimentary strata as a result of geologic forces.

Formation Damage

Any negative change in the ability of oil and gas to flow from the reservoir rocks into the well.

Formation Evaluation

The analysis of formations and fluid properties at depth by looking at drilll cuttings while drilling or on the wireline logs.

Formation Invasion

The tendency of drilling fluids to be forced into permeable formations during the drilling process.


A colloquial term for hydraulic fracturing, the treatment of low-permeability and low-porosity formations with the injection of highly-pressured fluids designed to stimulate production.

Fraction Of Effective Porosity Filled With Water

The effective porosity is the porosity that is interconnected – the bulk porosity minus the total isolated porosity.

Fracture Acidizing

The goal of this method is to create and clear fractures in the rocks around the wellbore, creating a path which allows hydrocarbons to bypass the damaged skin region.

Friction Reducer

An additive used to reduce friction forces experienced by tools and tubulars. Friction reducers are commonly used in horizontal and highly deviated wells where the friction forces limit the passage of tools and pipe along the wellbore.

Gas Hydrate

Molecules of methane that are trapped in ice molecules.

Gas Window

The range of temperature for which kerogen is converted to gas.

Geologic Sequestration

The injection of carbon dioxide into deep geologic formations suitable for long-term or permanent subsurface storage.

Geologic Structure

The arrangement of rocks that result from tectonic forces causing rocks to bend, fold and fault.


Associated with or produced by the heat of the Earth.

Geothermal Gradient

The rate of increase in temperature per unit of depth in the Earth. The geothermal gradient varies from location to location by average 25-30°C/km, or 15°F/1000 ft.


An inverted “U” shaped section of rigid piping used as a conduit for high pressure drilling fluid and connects the top of a vertical standpipe to a flexible Kelly hose that is connected to another gooseneck between the flexible line and the swivel pipe.


Block of rock, bounded by normal faults, that has dropped down relative to the blocks on either side.


Block of rock, bounded by normal faults, that has moved up relative to the blocks on either side.

Hydraulic Fracturing

Process by which liquids injected at high pressures into low permeability subsurface strata create fractures through which hydrocarbons and other fluids travel to the surface.

Hydraulic Head

The force per unit area exerted by a column of liquid from a height above the depth of interest.

Hydrogen Sulfide Sensor

A gas sensor that measure the amount of hydrogen sulfide gas.

Hydrostatic Gradient

The rate of change of fluid formation pressure over depth.

Hypocenter (focus)

Point within Earth’s crust where an earthquake originates.

Igneous Rock

Rock type formed by the cooling and solidification of lava or magma. Igneous rocks include extrusive or volcanic rocks formed at the Earth’s surface and intrusive or plutonic rocks formed at depth.

Inactive Fault

Fault which has not produced slip during recorded human history.

Induced Fracture

Fracture caused by excessive mud weight.

Induced Seismicity

Earthquakes related to human activity.

Intermediate Casing

A length of pipe used below the surface casing, but before production casing is run.  It is used to isolate zones of the open hole wellbore to allow for deepening of the well.

Isolated Porosity

The percentage of the porosity that is not connected to the permeable pore system.


Molecules with the same molecular formula but a different molecular structure.


A rectangular or hexagonal pipe that is screwed into the top of the drill string and transmits the rotation of the turntable and kelly bushing to the string.

Kelly Bushing

An adapter that fits inside the master bushing and transmits rotation to the kelly.


Naturally occurring insoluble and solid organic matter than can yield oil and gas upon heating.


When high pressure fluids enter the wellbore resulting in either a) Increase in mud return rate: A sudden increase in the flow of mud in the surface return line, or b) Increase in the mud pit volume: If mud is returning to the mud pit faster than it’s being pumped out wherein the fluid level within the pit will rise, or c) Flow with pumps off: If fluids are flowing from the well when the pumps are turned off.


A person that negotiates acquisitions and business deals for the exploration or development of mineral resources.

Leakoff Rate

The rate at which frack fluids escapes through the walls of the fracture.

Leakoff Test

A test performed to determine the strength (or fracture pressure) of a formation.


A chemical sedimentary rock that is composed of calcium carbonate (minerals calcite and aragonite) that precipitate from water in a lake or an ocean, or a biological sedimentary rock composed of skeletal fragments of marine organisms, or the obvious presence of fossil fragments. Limestones are usually deposited in warm shallow marine environments.

Line Heaters

Heaters used to prevent the formation of ice or gas hydrates.


Most casing reaches from the bottom of the well to the surface. In some cases, the casing top is below the surface. That string is called a liner.


The process in which rocks become compacted under pressure to become solid rock.

Logging While Drilling

The evaluation of formation while the borehole is actively being drilled or shortly after the hole has been drilled.


Logic behind an argument.

Lost Return

The loss of fluids in the annulus when fluid is pumped through the drillstring.


The mast is the reinforced steel tower that supports drilling loads and allows hoisting through a system of pulleys.

Master Bushing

The master bushing is inside the rotary table. It holds wedges called slips or the kelly bushing (only one or the other at any time) in it’s center and transmits rotational power to the kelly.

Matrix Acidizing

When acid is pumped below the frack gradient into the rocks immediately adjacent to the producing section of the well bore.

Maximum Sand Free Rate

The maximum production flow rate that a weakly consolidated reservoir will produce without producing sand.

Metamorphic Rock

Rock type formed by the transformation of existing rock type by heat and pressure.


Hydrocarbon consisting of 1 carbon and 4 hydrogen atoms, CH4.

Mineral Rights

Property rights to exploit or extract an area for minerals.

Miscible Gas Injection

A technique that reduces the viscosity of oil by dissolving gases such as CO2 in it.

Monkey Board

The monkey board is a platform about halfway up the derrick. The board is essentially a rack that is used to secure the upper end of a stand of pipe when it is removed from the well. The worker who guides pipes into the board is called the derrickman.

Mud Logger

A person that uses a variety of techniques to examine the drill cutting, as well as to keep records of drilling operations and the status of the well.

Mud Logging

A detailed log created by the examination of drill cuttings brought to the surface from depth by drilling mud.

Mud Mixer

The mud mixer is where drilling mud is made from bentonite clay and water. Barite and other materials are added to increase the density of the mud.

Mud Motor

A motor that uses the flow of the drilling mud at the bottom of the hole to turn the bit.

Mud Pit

Same as mud tank depending on site setup, is the place where drilling mud is stored until it is needed.

Mud Pumps/Suction Line

The suction line carries mud from the mud pit or tank into the mud pumps.

Mud Return Line

A pipe carrying mud that surfaces around the annulus from the bell nipple to the mud tanks or mud gas separators.

Mud Tank

The mud tank (or mud pit, depending on site setup) is the place where drilling mud is stored until it is needed.

Mud Weight Window

The range of equivalent densities or pressures that avoid drilling problems, generally between the pore pressure and the fracture pressure.


A very fine grained (grain size < 0.06 mm) clastic sedimentary rock composed of a mixture of clay and silt sized minerals.


Sources of renewable energy that do not cause environmental pollution such as wind, geothermal energy, solar and tides.

Normal Fault

Fault where the hanging wall has moved down relative to the footwall

Normal Faulting Stress Regime

Region where extensional forces are acting bodies of rock resulting in a normal fault to form.  One fault block drops down with respect to the other.

Normal Pore Pressure Gradient

The pore pressure inside the pore space in the rock column from the surface to the total depth of the well.


Hydrocarbon consisting of 8 carbon atoms, CH3(CH2)6CH3.

Oil and Gas Window

Temperature dependent interval in the subsurface where oil is generated and expelled from the source rock at approximately 60–120°C. At higher temperatures, gas will be formed.

Oil Window

The temperature range in which kerogen is converted to oil.


Thickness of rock or soil overlying a particular rock layer of interest, such as a reservoir or source rock.


A downhole tool used to engage the outside of a tube or tool during a fishing operation.

P and A

Plug and abandon.


Primary or pressure wave; first of two body waves to arrive at a seismic station after an earthquake; P-waves are compressional waves, thus, their oscillation moves in the direction the wave travels.


A device that is run into the wellbore that expands to externally seal the wellbore hole.


Appeal to the emotions of the audience.

Percussive Sidewall Coring

A core taken from the wall of the well bore by firing hollow bullets into the formation.


To create holes in the liner or casing to allow for communication between the wellbore and the producing formation.

Perforating Gun

A device used to perforate the lining or casing of oil and gas wells.

Petroleum Exploration Geologist

A geologist that uses geological and geophysical techniques to determine where reservoir deposits may be located for extraction.

Petroleum System

A system that includes all the geologic elements and processes that are essential if an oil and gas accumulation were to exist. These include source rock, migration pathway, reservoir, trap and seal. Relative timing of each element is also very important.


A geologist who studies the physical and chemical properties of rocks and their interactions with fluids including determining the volume of hydrocarbons present in a reservoir, and the potential for hydrocarbons to flow through the reservoir rock.

Pipes Are Made Up

Pipes that have been screwed together.

Plate Tectonics

Theory that the Earth’s outer shell is divided into several hard and rigid sections or plates that move over the mantle.


Document drawn to scale showing divisions of tracts of land.


A molecule made up of repeating units.

Plug and Perf

Plugging and perforating a certain zone at depth.

Pore Pressure

Pressure of the fluids within the pores of a layer of rock.

Pore Throat

Open channel connecting two pores within a rock matrix.

Pressure Gradient

The change in pressure divided by the distance over which that change occurs.

Pressure Gradient Limit

Equivalent to the overburden gradient, if exceeded the pressure would lift the crust.


First-ranking importance or authority.

Primary Recovery

The first stage of recovery, during which natural reservoir pressure or surface pumping cause hydrocarbons to flow towards the well at an economical rate.

Primary Term

The length of time that a lease remains effective for, after which the lease expires.

Produced Water

Water that is produced along with oil and gas production, often considered brine and sometimes containing heavy metals and small amounts of naturally occurring radioactive materials.

Production Casing

A casing string that is set across the reservoir interval.

Production Tubing

Tubing used to produce wellbore fluids.


Hydrocarbon consisting of 3 carbon atoms, CH3CH2CH3.


Particles mixed with fracturing fluid to hold fractures open after hydraulic fracturing.

Rayleigh Wave

Surface wave which “rolls” Earth’s surface through a combination of compressional and transverse motion.


Heats the amine solution to causing the H2S and CO2 from the gas to rise to the top of the tank for collection.


A tank where the hydrogen sulfide and carbon dioxide rich amine solution is transferred to be heated.

Reservoir Dogs

A 1992 American crime film written and directed by Quentin Tarantino in his feature-length debut.

Reservoir Drive

Natural forces in the reservoir that displace hydrocarbons out of the reservoir into the wellbore and up to the surface.

Reservoir Rock

Rock where oil and gas migrate to and are trapped underground. Good reservoir rocks ideally have high permeability and porosity, such as with sandstones.

Reverse Fault

Fault where the hanging wall has moved up relative to the footwall.

Rift Valley

An elongated depression that forms from the downward displacement of block due to the separation of tectonic plates.

Rigging Down

Dismantling the rig.

Rigging Up

When the drilling rig is moved on location and it is time to set up the drill rig.

Rock Volume

The overall volume of the reservoir rock thought to contain oil.

Rotary Sidewall Coring

A core taken from the wall of the well bore by a drill that cuts and extracts the core plug.

Rotary Table

The revolving or spinning section of the drillfloor that provides power to the drillstring in a clockwise direction.

Royalty Payment

A portion of the gross value of any oil or gas produced from that lease that is paid to the mineral owner.

Rule of Capture

A rule that establishes non liability and ownership of captured natural resources.


Secondary or shear wave; second of two body waves to arrive at a seismic station after an earthquake; S-waves are shear waves, thus, their oscillation moves in a direction perpendicular to the direction the wave travels.

Salt Bed

A type of sedimentary rock formed in arid environments, and are also referred to as evaporates.

Sanding Off

A situation that can happen during hydraulic fracturing in which proppant completely plugs the fractures being opened, preventing fluid from entering the formation.


A fine to medium grained clastic sedimentary rock composed of sand sized grains (>0.06 mm, < 2 mm), sometimes called an arenite. Sandstones are predominantly composed of quartz and feldspar minerals.

Screening Out

When solids create a bridge across a perforated zone and restricts fluid flow.


The process of removing impurities, water, liquid hydrocarbons or traces of others gases (like H2S) by directing gas through a scrubber, a device in which gas is mixed with a suitable liquid to absorb or wash out the constituents to be removed.

Seal Rock

A low permeable rock layer that may trap gas or oil, also called a cap rock.

Secondary Recovery Method

The second stage of hydrocarbon production during which water or gas are injected into the reservoir so that reservoir pressure can be maintained and displace the hydrocarbons towards the wellbore.


Rock type formed by the compaction material, not necessarily just sediments, at the Earth’s surface. Sedimentary rocks include clastic sedimentary rocks, chemical sedimentary rocks and evaporates.

Sedimentary Basin

A region of earth where there is subsidence over a long term. The subsidence creates accommodation space for sediments to infill.

Sedimentary Rock

Rock formed by the lithification of sand, silt, shells, and other materials that collect in a depositional environment.


Main tool for measuring land movement using either weights on a frame with a stylus to record the movement or digital instruments.

Self Contained Breathing Apparatus

Provides breathable air when atmospheric conditions are dangerous and pose an immediate health risk.


The separators serve to separate the hydrocarbons into oil and gas components and to remove water.

Shale Gas

Natural gas that is formed and trapped in the shale source rock.

Shale Shaker

The shale shakers are used to remove rock cuttings that have come up from the bottom of the well from the mud so that it can be reused. The shale shakers consist of a vibrating grate. Rock chips are trapped in the grate and slide off of it, while mud flows between the metal parts.


A fine grained clastic sedimentary rock composed of clay minerals and silt sized grains of other minerals including quartz and calcite. Shale is the most abundant sedimentary rock, deposited in both continental and marine depositional environments; not all shales have high organic matter contents.


Shear stresses act parallel to a fault plane but in opposing directions on either side of the surface causing displacement or slip.

Shear Strength

The strength (ability) of a material to resist forces that cause the material’s internal structure to slide against itself.


As oil moves to the surface, its volume tends to decrease.


A type of mudstone that contains at least 50% silt (grain size <0.06 mm) by composition.

Skin Region

The region below the frack gradient immediately adjacent to the producing section of the well bore.


Slickline is a single strand of cable that can be used to lower various objects into the bore hole and bring them back up.

Slickwater Solution

Low-viscosity fluid pumped at high rates to generate narrow fractures with low concentration of proppant.

Sliding Sleeve

A completion device used to connect the production conduit with the annulus.

Smallest Stress

The least stress acting on a surface.

Social Network

Social structure made up of actors and the ties and interactions between actors.

Source Rock

One component of a petroleum system. A rock that has a total organic carbon content of at least 1% from which hydrocarbons have been generated or are capable of being generated. Typically fine grained, relatively impermeable materials.

Source Rocks

Rocks capable of generating oil and gas under the right conditions.


Drillers’ slang for starting the actual drilling process.


An additive to solutions to inhibit chemical degradation.


The standpipe connects to the kelly or the top drive through a rotary hose.


2 or 3 single joints of drillpipe or drill collars that remain screwed together during tripping operations.

Steam Flooding

When superheated steam is injected into the ground to heat the oil.


A scientist that studies sedimentology and stratigraphy.

Stratigraphic Sequence

A chronologic succession of sedimentary rocks. As opposed to looking at similar rocks across an area, sequence stratigraphy is concerned with the study of the genetically-related facies that occur across the same time boundaries.  Facies are identifiable sections of a rock different from their surrounding geologic neighbors. A single layer of rock can have multiple facies within it, distinguishable by the details of their composition.


A branch of geology that studies sedimentary rocks and their layers.

Strike-slip Fault

Fault where two blocks of rock slide past each other horizontally without any significant vertical movement.


A string (of casing) is a long section of connected oilfield pipe that is lowered into a wellbore and cemented.

Structural Trap

An area in the subsurface that creates an impedence to oil flow formed as a result of some kind of movement of the rock layers. Structural traps include anticlinal, fault, and salt dome traps.


The substructure supports the entire load of the drilling rig. The substructure provides physical support for the rig platform, derrick, and the entire drill string, and needs to be level, with a strong foundation of packed earth or cement.

Surface Casing

A large diameter pipe set in shallow formations designed to protect fresh water aquifers.

Subsurface Containment

Practice of containing fluids within their respective zones during oil and gas operations.


Mechanical device that suspends the weight of the drillstring designed to allow rotation of the drillstring beneath it conveying high volumes of high pressure drilling mud between the rigs circulating system and the drillstring.

Swivel Pipe

Mechanical device that suspends the weight of the drillstring designed to allow rotation of the drillstring beneath it conveying high volumes of high pressure drilling mud between the rigs circulating system and the drillstring.


Structurally folded rocks that formed as a result of compressional tectonic forces. The layers dip in the direction of the center or axis of the fold. The older rock beds are on the “outside” of a syncline. Synclines form the bottom of an “S”.

Tectonic Force

Forces that subject rock to stress and strain as a result of the movement of the tectonic plates.

Tensile Strength

The ability of a material to withstand a pulling (tensile) force before it stretches and breaks.

Tertiary Recovery

The third stage of hydrocarbon extraction where techniques such as water flooding or pressure maintenance, sometimes referred to as enhanced oil recovery.

The Pad

A preparatory stage before high-pressure fracturing begins in which slickwater (without proppant) is put in the well to lubricate and slightly open fractures.

Thermogenic Production

Hydrocarbons formed from the cracking of kerogen at increased pressures and temperatures. Natural gas production is dominant in the last stage of generation called metagenesis.

Three-Phase Separator

A vessel that separates well fluids into gas, oil, and water.

Top Drive

A device that turns the drillstring and consists of one or more motors connected to a short section of pipe called a quill. The topdrive is suspended from the hook, so the rotary mechanism is free to move up and down the derrick.

Traveling Block

The travelling block is part of the block and tackle system used to raise and lower the drill string. It consists of several pulleys in sequence, and it is raised and lowered along with the drill string.

Trip Out

The process of removing the entire drill string from the hole.

Trip Tank

The trip tank is a separate mud storage tank that is used during tripping operations. Fluid from the trip tank is continually circulated through the well during tripping.

Tripping Out

The process of removing the entire drill string from a well thousands of feet deep.

Two-Stage Separator

Separates the produced fluids into liquid (water and oil) and gas phases.

Unconventional Resource

Hydrocarbon reservoirs that have low permeability and porosity that are difficult to recover without enhanced oil recovery methods.

Underground Injection Control

Environmental Protection Agency program for protecting underground sources of drinking water by regulating the construction, operation, permitting, decommissioning and closure of wells used to inject fluids underground.

Underground Source of Drinking Water

Aquifers and other stores of groundwater defined legislatively by the Code of Federal Regulations (40 CFR 144.3).

Vertical Pressure

Stress acting vertically on a horizontal plane.

Vertical Stress Gradient

Stress acting vertically on a horizontal plane as function of elevation.


To make a liquid more viscous.


Referring to a liquid, thick or sticky, not flowing easily.

Vitrinite Reflectance Analysis

Maybe add that we are looking at the reflectivity of vitrinite grains from a rock sample under a microscope, where vitrinite is type of woody kerogen. The reflectivity changes predictably and consistently under heating.

Vug or Mold

A cavity or large pore space in rock, creating through the dissolution of a previous deposited mineral.

Wastewater Injection

Process by which wastewater or contaminated water from any industrial operation is injected into deep subsurface formations for permanent disposal and storage.

Water Table

The upper limit of the saturated portion of an aquifer.


A method in which hot water is injected into a reservior to reduce the viscosity of oil to make it easier to recover.

Waterflood Technique

When water is pumped into an injection well located near the producing well.

Well Control

Containing pressure in a well in order to keep fluids and gases from entering the drill string and annulus.

Well Log

The measurements of the physical properties of a rock formation in or around a wellbore displayed versus depth and/or time.

Well Logging

The process of collecting data downhole using a variety of sensors.


The system of spools, valves and adaptors that provide pressure control of a production well.

Wellhead/Casing Head

The wellhead is the primary pressure containment system for a well. It is where surface equipment interfaces with the borehole. Typically, the well head is welded to the first string of casing cemented into the hole; drilling continues through the top of the wellhead and BOP, which is mounted on the wellhead.


An inclined surface that forces the drill bit to cut into the side of the hole and start on a new path.


A cloth cone mounted on a mast to indicate direction and strength of wind.

Wireline Logging

Logging that employs an electrical cable to lower tools into the borehole and to transmit data.

Wireline Tool

Instrument that is lowered into a borehole by the wireline cable, generally to take measurements of the rock formations at depth.