• Forgot Your Password?
  • Please enter your email that is on file with Waveland.
  • Email

Energy Glossary




Lag time The time it takes for cuttings to be carried (circulate) from the bottom of the borehole up to the surface by the mud system.
Landman A self-employed individual or company employee who secures oil and gas leases, checks legal titles, and attempts to cure title defects so that drilling can begin.
Landowner royalty The share of the gross production of the oil and gas on a property without deducting any of the cost of producing the oil or gas. The usual landowner’s royalty is one-eighth to one-quarter of gross production.
Lease (Oil and Gas) A contract by which the owner of the mineral rights to a property conveys to another party, the exclusive right to explore for and develop minerals on the property, during a specified period of time.
Lease Broker An individual engaged in obtaining leases for speculation or resale.
Lifting costs The costs of producing oil from a well or lease; the operating expenses.
Limestone Sedimentary rock largely consisting of calcite. On a world-wide scale, limestone reservoirs probably contain more oil and gas reserves than all other types of reservoir rock combined.
Liquefied natural gas (LNG) Natural gas (primarily methane) that has been liquefied by reducing its temperature to -260 degrees Fahrenheit at atmospheric pressure.  Once a liquid, it can be more readily transported by ship to end-use markets, then re-gasified for movement through a pipeline.
Logs Records made from data-gathering devices lowered into the wellbore. The devices transmit signals to the surface which are then recorded on film and used to make the record describing the formation’s porosity, fluid saturation, and lithology. The filing of a log is required by the federal government if the drill site is on federal land.
Lost circulation A serious condition that occurs when drilling mud pumped into the well does not return to the surface, but goes into the porous formation, crevices, or caverns instead.


MCF Thousand Cubic Feet
MCFGPD Thousand Cubic Feet of Gas per Day
Midstream Downstream of the wellhead, including gathering, gas and liquids processing, and pipeline transportation.
Migration The movement of oil and gas through layers of rock deep in the earth.
Milling Cutting a “window” in a well’s casing with a tool lowered into the hole on the drillstring.
Mineral Rights The ownership of all rights to gas, oil, or other minerals as they naturally occur in place, at or below the surface of a tract of land.
MMBO Million Barrels Oil
MMCF Million Cubic Feet
MMCFGPD Million Cubic Feet of Gas per Day
Mud A fluid mixture of clay, chemicals, and weighting materials suspended in fresh water, salt water, or diesel oil and used during drilling activities.
Mud engineer A technician responsible for proper maintenance of the mud system.
Mud Log A record of information derived from examination of drilling fluid and cutting from the formation.
Mud logger A technician who uses chemical analysis, microscopic examination of the cuttings, and an assortment of electronic instruments to monitor the mud system for possible indications of hydrocarbons (shows).


Natural gas A mixture of hydrocarbon compounds and small amounts of various nonhydrocarbons (such as carbon dioxide, helium, hydrogen sulfide, and nitrogen) existing in the gaseous phase or in solution with crude oil in natural underground reservoirs.

or natural gas liquids

Fuels that originate from the remains of living things, such as coal, oil, natural gas, and peat.
Natural gas processing plant Facilities designed to recover natural gas liquids from a stream of natural gas that may or may not have passed through lease separators and/ or field separation facilities.  These facilities control the quality of the natural gas to be marketed.  Cycling plants are classified as gas processing plants.
Net pay Is the thickness of productive oil- or gas-saturated rock that has been encountered during drilling.  A company may drill a 15,000 foot well and encounter 300 feet of ne t pay in several intervals of 100 feet each, for example.  The development well is designed to produce onl y from the net pay.
Net Revenue Interest The percentage of revenues due an interest holder in a property, net of royalties or other burdens on the property. A landowner leases his mineral rights to an oilman. The landowner retains a royalty of 1/8 (=12.5%); his net revenue interest is 12.5%. The oilman’s net revenue interest would be 87.5% (=100%12.5%).


Octane An hydrocarbon of the paraffin series. It is liquid at ordinary atmospheric conditions, although small amounts may be present in the gas associated with petroleum.
Octane number A performance rating used to classify motor fuels by grading the relative antiknock properties of various gasolines. A high-octane fuel has better antiknock properties than one with a low number.
Offset well A well drilled near the discovery well. Also a well drilled to prevent oil and gas from draining from one tract of land to another where a well is being drilled or is already producing.
Oil column The vertical height (thickness) of an oil accumulation above the oil-water contact.
Oil gravity The density of liquid hydrocarbons, generally measured in degrees.
Oil in place The crude oil estimated to exist in a field or a reservoir. Oil in the formation not yet produced.
Oil Rig A drilling rig that drills for oil and gas.
Oil shale A fine-grained, sedimentary rock that contains kerogen, a partially formed oil. Kerogen can be extracted by heating the shale, but at a very high cost.
Oilfield services Described as service companies that do work in and for the oilfield. These services may include: cementing, perforating, trucking, logging, etc.
OPEC An international oil cartel originally formed in 1960 and including in 1983: Saudi Arabia, Kuwait, Iran, Iraq, Venezuela, Qatar, Libya, Indonesia, United Arab Emirates, Algeria, Nigeria, Ecuador, and Gabon. (Organization of Petroleum Exporting Countries)
Operator The individual or company responsible for the drilling, completion and production operations of a well, and the physical maintenance of the leased property.
Organization costs Direct costs incurred in the creation of a new business organization such as an oil and gas limited partnership.
Overriding Royalty Interest These interests entitle their owner(s) to a share of the mineral production from a property or to a share of the proceeds therefrom. They do not contain the rights and obligations of operating the property and normally do not bear any of the costs of exploration, development, and operation of the property.


Packer A flexible rubber sleeve that is part of a special joint of pipe.
Pay zones The term to describe the reservoir that is producing oil and gas within a given wellbore. Pay zones (or oil reservoirs) can vary in thickness from one foot to several hundred feet.
Payoff A specific sedimentary layer in a cross section of land, especially one in which a petroleum reservoir is found.
Payout The amount of time it takes to recover the capital investment made on a well or drilling program.
Perforating gun An instrument lowered at the end of a wireline into a cased well. It contains explosive charges that can be electronically detonated from the surface.
Perforation A method of making holes through the casing opposite the producing formation to allow the oil or gas to flow into the well. See the Gun perforation.
Permeability The capacity of a rock to transmit fluids.  A tight rock, sand or formation will have low permeability and thus, low capacity to produce oil or gas, unless the well can be fracture-stimulated to increase production.
Petrochemicals Chemicals derived from crude oil or natural gas, including ammonia, carbon black, and other organic chemicals.
Petroleum Strictly speaking, crude oil. Also used to refer to all hydrocarbons, including oil, natural gas, natural gas liquids, and related products.
Petroleum engineer A term including three areas of specialization: 1) Drilling engineers specialize in the drilling, workover, and completion operations, 2) Production engineers specialize in studying a well’s characteristics and using various chemical and mechanical procedures to maximize the recovery from the well, 3) Reservoir engineers design and execute the planned development of a reservoir. Many U.S. universities offer BS, MS, and Ph.D. degrees in petroleum engineering.
Petroleum geologist A geologist who specializes in the exploration for, and production of, petroleum.
Pinch out The disappearance of a porous, permeable formation between two layers of impervious rock over a horizontal distance.
Pipeline A tube or system of tubes used for the transportation of oil or gas. Types of oil pipelines include: lead lines, form pumping well to a storage tank; flow lines, from flowing well to a storage tank; lease lines, extending from the wells to lease tanks; gathering lines, extending from lease tanks to a central accumulation point; feeder lines, extending from leases to trunk lines; and trunk lines, extending from a producing area to refineries or terminals.
Pipeline gas Gas under enough pressure to enter the high-pressure gas lines of a purchaser; gas in which enough liquid hydrocarbons have been removed so that such liquids will not condense in the transmission lines.
Platform Either a drilling or production facility offshore.
Play or trend Is an area or region where there is a great deal of drilling and production activity and involves a group of geologically related fields and prospects.  A play is a set of known  or postulated oil and gas accumulations sharing similar geologic, geographic, and temporal properties, such as source rock, migration pathway, timing, trapping mechanism, and hydrocarbon type.  A play differs from an assessment unit; an assessment unit can include one or more plays.  A play is often used to refer to a natural gas accumulation, i.e., a natural gas shale play, an oil play.
Plug back To block off the lower section of the borehole by setting a plug, in order to perform operations in the upper part of the hole.
Plugging a well Filling the borehole of an abandoned well with mud and cement to prevent the flow of water or oil from one strata to another or to the surface.
POD A 10- to 15-acre tract of land from which both drilling and production takes place.
Pooling A term frequently used interchangeably with “Unitization” but more properly used to denominate the bringing together of small tracts sufficient for the granting of a well permit under applicable spacing rules.
Pore Spaces Very small openings where liquid and/or gas can collect.
Porosity Areas in which production of crude oil is presumed possible owing to geological inference of a strongly speculative nature.
Possible reserves Areas in which production of crude oil is presumed possible owing to geological inference of a strongly speculative nature.
Present net value The present value of the dollars (income, or stream of income) to be received at some specified time in the future, discounted back to the present at a specified interest rate.
Primary recovery Production in which oil moves from the reservoir, into the wellbore, under naturally occurring reservoir pressure.
Primary term The basic period of time during which a lease is in effect.
Private Placement Offering A securities (investment) offering not intended for the general public. By meeting certain criteria, such an offering may qualify for exemptions from registration with the Securities and Exchange Commission of the Federal government.
Probable reserves Areas which are unproven but presumed capable of production because of geological inference, for instance, proximity to proven reserves in the same reservoir.
Producing horizon Where the well is actually produced, since it may be drilled to a greater depth.
Producing platform An offshore structure with a platform raised above the water to support a number of producing wells.
Production A term commonly used to describe taking natural resources out of the ground.
Production test A test made to determine the daily rate of oil, gas, and water production from a potential pay zone.
Proppants Materials used in hydraulic fracturing for holding open the cracks made in the formation by the fracturing process. Proppants may consist of sand grains, beads, or other small pellets suspended in fracturing fluid.
Prospect Is a lease or individual well that may be drilled because geology indicates it will probably be productive.
Prospective acreage Is where there are geologic, seismic and/or other reasons to believe the subsurface may contain oil or gas. Drilling will be necessary to form a conclusion.
Proved acreage Is where the existence of oil or gas has been proven by drilling exploration and appraisal wells.
Proved developed reserves Are reserves that can be expected to be recovered through existing wells, with existing equipment and known operating methods.
Proved reserves Are reserves of oil or gas that can be economically produced under current economic conditions and commodity prices, and given current technologies, within five years, according to complex guidelines in force by the Securities and Exchange Commission (SEC).
Public lands Any land or land interest owned by the federal government within the 50 states, not including offshore federal lands or lands held in trust for Native American groups.
PUDs Proved undeveloped reserves that may be soon drilled and placed into production using existing technologies, recovered from new wells on undrilled, proved acreage, or from existing wells where a relatively major expenditure is required for completion.
Pump A device that is installed inside or on a production string (tubing) that lifts liquids to the surface.
Pump off To pump a well so rapidly that the oil level falls below the pump’s standing valve, rendering the well temporarily dry.
Pumping well A well that does not flow naturally and requires a pump to bring product to the surface.


Quitclaim deed A document by which one party (grantor) conveys title to a property, by giving up any claim which he may have to title (although he does not profess that claim is necessarily valid).


R&D Research and development.
Ram A closure mechanism on a blowout-preventer stack.
Re-entry A well was abandoned, but subsequent drilling and production in the area suggests that a potential pay zone in the well was missed or passed over.
Reamer A tool used to enlarge or straighten a borehole.
Reclamation The restoration of land to its original condition by re-grading contours and replanting after the land has been mined, drilled, or otherwise has undergone alteration from its original state.
Recoverable resources An estimate of resources, including oil and/or natural gas, both proved and undiscovered, that would be economically extractable under specified price-cost relationships and technological conditions.
Reef A buildup of limestone formed by skeletal remains of marine organisms. It often makes an excellent reservoir for petroleum.
Refining Manufacturing petroleum products by a series of processes that separate crude oil into its major components and blend or convert these components into a wide range of finished products, such as gasoline or jet fuel.
Relief well A well drilled in a high-pressure formation to control a blowout.
Reserve That portion of the identified resource from which a usable mineral and energy commodity can be economically and legally extracted at the time of determination.
Reserve (pool) A porous and permeable underground formation of producible oil and/or natural gas, confined by impermeable rock or water barriers, and characterized by a single natural pressure system.
Reservoir A porous and permeable subsurface formation that contains oil or gas and is surrounded by rock that separates the oil or gas contents from other reservoirs.
Reservoir pressure The pressure at the face of the producing formation when the well is shut-in. It equals the shut in pressure at the wellhead plus the weight of the column of oil in the hole.
Retained Interest A fractional interest reserved by the owner of a whole interest when the balance of the whole interest is transferred to another party.
Reversionary interest An interest in a well or property that becomes effective at a specified time in the future or on the occurrence of a specified future event.
Roof rock A layer of impervious rock above a porous and permeable formation that contains oil or gas.
Rotary drilling A method of well-drilling that employs a rotating bit and drilling mud to cut through rock formations.
Roughnecks Members of the drilling crew.
Roughnecks The amount of oil or gas estimated to be produced over a well’s lifetime, prior to plugging and abandoning the well because it is no longer economic to produce.
Round trip Pulling the drillpipe from the hole to change the bit, then running the drillpipe and new bit back in the hole.
Roustabout A semi-skilled hand who looks after producing wells and production facilities.
Royalty A payment to a landowner or mineral rights owner by a leaseholder on each unit of resources produced.
Royalty interest Is the right to receive a specified amount of the gross income or production from a mineral property. A royalty interest, as opposed to a working interest, is not charged with the costs of exploration or development drilling, or operation, and is therefore treated as a nonoperating interest for federal income tax purposes.
Run ticket A record of the oil run from a lease tank into a connecting pipeline. An invoice for oil delivered.
Running the tools Putting the drill pipe, with the bit attached, into the hole in preparation for drilling.