B

Back off

Unscrewing of the drill string’s components down hole. When a drill string gets stuck it is often necessary to back off the string as deep as possible in order to recover as much of the drill string as possible. 
 

Back pressure valve

A check valve installed through the christmas tree in a tubing hanger. This prevents the fluids of the well from flowing out. 
 

Backwashing

When a fluid is sent in the opposite direction through a filter to rinse it for impurities that have blocked it. 
 

Bad oil

Oil mixed with water so finely it is necessary to heat up the fluid in order to separate the two. 
 

Barefoot completion

A method to prepare a well for production where casing is not used. 
 

Barite

Also known as barytes. A heavy metal that is mixed into the drilling mud to make it heavier. This is done so the drilling mud is able to resist if exposed to major pressure down hole.
 

Barrel

A cubic unit within the oil business. 1 barrel corresponds to 159 litres or 42 US gallons. 
 

Basic petrochemical

A term describing the basic raw materials extracted from crude by cracking. 
 

Batch

A certain amount of oil or a refined oil product located in a pipeline or tank. 
 

Bed

Geological expression for layers (stratums) of sediments, which separate themselves from other layers below or above. The stratum must be distinguishable from adjacent beds to qualify for the term bed. It is the smallest stratigraphic unit and is usually about 0,4” or more in thickness.

Bed

Bedrock

A firm layer of rocks lying beneath the sediments. 
 

BHA

See Bottom hole assembly
 

BHP

See Bottom hole pressure
 

Bit

This tool is used to crush or cut the rocks. It is the bottom part mounted on the drill string and consists of teeth of or diamante-covered wheels that crush their way through the underground. Also called drill bit. 

Bit breaker

A heavy metal plate that fits into the rotating bit. It is used to hold the bit when it needs to be unscrewed from the tool string. 
 

Bitumen

Another word for asphalt. 
 

Bleeding

To slowly tap fluids from a container or tubing. 
 

Blowout

When gas, oil or salt water flows into the wellbore in an uncontrolled manner. 
 

Blowout preventer (BOP)

At the top of the well, a large valve may be installed to prevent blow-outs. If personnel loses control of fluids in the well, it can be closed and control regained.

Boom

A device that is laid out to limit the spreading of oil if leakage should occur. 
 

Booster station

Device on a pipeline used to pump oil or gas through the pipe. Several booster stations can be placed on the pipeline depending on the length of it. 
 

Borehole

The ”raw” hole in the subsoil caused during drilling before casing has been mounted. 
 

Bottlenecking

Malformation of the casing, which happens if the pressure from the drill stem or the surrounding pressure has been too high. 
 

Bottom hole assembly (BHA)

The lower part of the drill string that consists of the bit, drill collars, heavy weight drill collars and the rest of the assisting equipment. 
 

Bottom hole pressure (BHP)

Formation pressure at bottom of well. If the pressure is falling, it may mean that the occurrence of carbon has been drained. 
 

Bottom out

Reaching objective drilling depth. 
 

Bottoms

The hard substances that do not evaporate during the distillation process. Also a term for sediments in bunker fuel tanks; usually slag and water. 
 

BGS

British Gas Corporation. 
 

BNOC

British National Oil Corporation. 
 

Brent crude

A type of crude originating from the North Sea. 
 

Brine

See produced water
 

Bring in the well

Preparing a well for production by initiating the reservoir flow. This is the last part of the completion. 
 

Brown field

A field with reduced production or a field that is reaching the end of its productive life. 
 

BTU (British thermal unit)

Unit of measurement for the degree to which a fluid can be heated. 
 

Bulk plant

Storage 
 

Bull Plug

A cylinder shaped device with a rounded tip used for sealing the casing in order to ensure an even pressure. 
 

By-pass

Pipe that creates passage through a valve or other control mechanism. It is used to equalise pressure differences prior to opening a valve, maintaining production during adjustments or repairing the main system.