Check the terms and concepts specific of the oil and gas industry:



a) term used in sedimentology to represent a volume of sediment deposited at a determined geographic position in a sedimentary basin; b) represents the phase of development of an oil system when the oil that migrates from the source rock is absorbed and retained in the reservoir; c) the quantity of oil retained in a trap (sealant rock). 


Acronym for "Agência Nacional de Petróleo, Gás e Biocombustíveis", the Brazilian National Agency of Oil, Natural Gas and Biofuels.



Process of measuring the depths of oceans, seas and other bodies of water using acoustic systems (echo sounders). 


Part of a sedimentary basin where concessionaires carry out oil exploration and production operations. 


Uncontrolled leak of gas, oil or any other fluid originally contained in the reservoir into the atmosphere, seabed or other rock formation. An accident during which suddenly and without control there is a continuous expulsion of fluid from an oil well. This is caused by the pressure in the formation being higher than the pressure applied by the drilling or intervention fluid column in the well.

Blowout preventer (BOP)

Set of safety valves installed in the wellhead to avoid blowout at the surface. 


The deepest part of the well or part furthest from the surface.


Choke aperture

The diameter of the device controlling the flow of fluid from the formation (choke).

Christmas tree

Set of valves, connections and adaptors installed at the wellhead to control the flow to the surface.


Sequence of operations carried out after the drilling of the well in order to transform it into a production or an injection well.


Contract through which the ANP grants companies that meet the established technical, economic, legal and fiscal requirements the right to carry out oil and natural gas exploration and production activities in Brazilian territory. 

Concession agreement

Contract stating the responsibility that companies have in the exploration and production of oil in areas under their control, and stating that they have property rights to the oil produced if successful. 

Coring sample

Sample obtained through coring; one or a range of pieces of rock obtained from coring parts selected for analysis.


Declaration of commerciality

Notification made by concessionaries to the ANP declaring that one or more of the deposits in their concession area is commercially viable, and therefore confirming their intention to develop it. This marks the end of the exploration phase and the beginning of the development phase.


Reservoir or deposit identified by direct or indirect research methods that has not yet been scaled or economically evaluated. 


Set of operations and investments destined to enable production activities in an oil or gas field. 

Development well

Well drilled in a development or production area.

Discovery well

Well resulting in the discovery of a productive or potentially productive accumulation of oil or natural gas, which may be located in either shallow or deep areas of a field or adjacent to it. 


Term applied to activities related to the refinery of crude oil, the processing of natural gas in gas plants and the transport and trade of derivatives. 

Drill cuttings

In oil drilling, the rock fragments retained in the slurry separation sieve.

Drill Stem Test (DST)

Test applied to geological formations in cased and perforated wells via a pipeline.


Tool used during drilling to mechanically drill the rock and gradually penetrate the subsoil.

Drill string

Column made up of drilling pipelines, including heavy pipelines, the components that make up the bottom of the well, the drill and the other tools used in well drilling designed to apply weight and rotate the drill, supply the drilling fluid, maintain the well calibrated and ensure the correct inclination and direction of the well.


Activity involving all of the operations required to construct a well up until the moment it is handed over to the completion team.

Drilling fluid

Complex mixture of liquids, solids and in some cases gases. Its main function is to transport solids generated during the drilling of a well to the surface and to promote their separation in a solids extraction system.


Vessel equipped with a drill rig and other equipment required for rotary drilling.

Dry well

A well where there is no movable oil and/or natural gas. 


Emergency plan

Set of measures that determine and establish the responsibility of each sector and the actions to be taken immediately after an incident, as well as defining the adequate human resources, material and equipment for the prevention, control and response to an incident. 

Environmental Impact Report

Document written in non-technical language that presents the results of technical and scientific studies evaluating environmental impact, communicating them to all interested parties. 

Environmental licence

Administrative act granted by the relevant authority that contains the conditions, restrictions and environmental control measures to be observed by its holder related to the location, installation, expansion or operation of activities within projects using environmental resources that are effectively or potentially polluting or that can cause environmental damage. 


Set of activities to evaluate areas, with the aim of discovering and identifying deposits containing oil or natural gas. 



Fixed or mobile structures used in oil or natural gas drilling, production, storing or transport activities. 


Partial or total sale of the rights to a concession. The company acquiring concession rights is in a farm-in process and the company selling them is in a farm-out process. 


Partial or total sale of the rights to a concession. The company selling its concession rights is in a farm-out process and the company acquiring them is in a farm-in process.  


Oil or natural gas producing area, from a continuous reservoir or more than one reservoir at varying depths. 

Field abandonment

The set of operations performed to permanently abandon wells, deactivate production facilities and recuperate the areas surrounding these facilities.


Gas kick

Loss of control during the well drilling phase caused by the pressure in the formation being higher than the pressure exerted by the fluids fed into the well. If this situation is not brought under control it can lead to a blowout.

Gas reservoir

All reservoirs that contain hydrocarbons predominantly in the gaseous phase. 


Heavy oil

Crude oil with a low API grade due to a higher proportion of long chain hydrocarbons. 


Compound made up of just carbon and hydrogen molecules. A mixture of organic compounds that make up the portion of the material obtained from a production well with the most economic interest. Oil and natural gas are examples of hydrocarbons. 


Lateral core

Cylindrical rock sample obtained at a right angle to the well shaft.

Light oil

Relative, non-standard classification related to API grade. Light oils generally have an API of 30º or higher. 

Local content

Aggregate value of national components required for the production of determined goods or services.

Lubricating oil

Liquid obtained by distillation of crude oil. 



The linking of a floating unit, normally a ship, to a quay, buoy or other vessel.


Natural gas or gas

Any hydrocarbon in the gaseous phase under normal atmospheric conditions extracted directly through oil or gas reservoirs, including humid, dry, residual and rare gases. 

Near accident

Any unexpected event presenting a potential risk to operational safety and which does not cause damage to human health or the environment. 



Located or operated at sea.

Oil and natural gas industry

Set of economic activities related to the exploration, development, production, refinery, processing, transport, import and export of oil, natural gas and other aromatic hydrocarbon fluids and their derivatives. 


Crude oil or other hydrocarbons produced at the wellhead in liquid form. Includes distillates or condensates recuperated or extracted from natural gas. 

Oil in place

Estimated volume of crude oil in a reservoir or an oil field that has not yet been explored. 

Oil pipeline

Pipeline for the transportation of oil. Term usually used for long distance transport. 

Oil reservoir

All reservoirs that contain hydrocarbons predominantly in the liquid phase. 


Organization of Petroleum Exporting Countries. 

Operating company

Company that receives a concession to explore and produce oil or gas and operate in an oil field, being responsible for the purchase of goods and contracting of services for these activities.

Operating safety

Prevention, mitigation and response to events that can cause accidents on offshore facilities for the drilling and production of oil and natural gas that put human life or the environment at risk. This is implemented through the adoption of a management system that ensures the safety of our facilities during the whole life cycle. 


Platform support vessel

Vessel used to offer support to oil platforms, transporting supply materials such as cement, pipelines, slurry, saltwater, water and oil, etc. 

Plugging and abandonment

Well abandonment due to there being no further interest in continuing operations.


Set of coordinated operations to extract oil or natural gas from an ore deposit and prepare it for transport. 


Geological feature mapped as a result of geophysical studies and geological interpretation that justify the drilling of exploratory wells to locate oil or natural gas. 



Process of oil and natural gas extraction through production wells using the natural energy of the reservoirs or introducing energy through injection wells. 

ROV (Remotely Operated vehicle) support vessel

Vessel containing the entire supply and control infrastructure for a remotely operated vehicle (ROV).


Financial compensation paid monthly by concessionaires for each oil field, starting from the month in which production starts, which is then distributed between states, municipalities, the Brazilian Naval Command, the Brazilian Ministry of Science and Technology and a Special Fund, administrated by the Brazilian Ministry of Finance. 

Running in hole

Procedure of lowering tools into the well.

Running string into hole

Procedure in which the drilling column, production column, coating or pump shaft is lowered into the well.


Sedimentary basin

Depression in the earth where sedimentary rocks that may contain oil or gas accumulate. These may or may not be linked. 

Seismic imaging

Technique using seismic waves, which is the most frequently used to obtain information on geological formations at the surface. 

Seismic source

Point at which seismic waves are generated.

Shale gas

Gas obtained via oil shale retorting after separation of liquefied shale gas. 

Signing bonus

Value offered by the winning bidder in their proposal to obtain an oil and natural gas concession, which must be paid when they sign the concession agreement. 

Support vessel

Supply vessel


Temporary abandonment

Well abandonment when there is still an interest in continuing operations.


Unitisation of production

Feasibility, through a single project, of the development and production of a mineral deposit that spans concession areas belonging to different concessionaires or that enters areas that have not been granted, in order to optimize recovery and guarantee best practices. 


Water depth

Distance between the surface of the water and the seabed.

Well abandonment

The set of operations carried out to isolate fluid-bearing formations using cement plugs, remove surface equipment and recuperate the well location.


Equipment made up of spools, valves and adaptors connected to the top part of the well, which seals it, controls the flow and supports other equipment such as the tubing and coverings.
Dicionário do petróleo em língua portuguesa: exploração e produção de petróleo e gás: uma colaboração Brasil, Portugal e Angola/[editores] Eloi Fernández y Fernández, Oswaldo A.Pedrosa Junior, Antônio Correia de Pinho- Rio de Janeiro: Lexikon: PUC-Rio, 2009.
Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP) –