Glossary
Back-off |
the action of securing a section of drill-pipe while another is unscrewed from it. |
Bar |
unit of pressure. One bar is equal to .987 standard atmospheric pressure, or 14.5 pounds per square inch |
Barge |
a non-self-propelled vessel used as a base for drilling equipment, to carry cranes, support facilities, accommodation modules, etc., to lay underwater pipelines or to transport crude oil or its products over short distances. |
Barrel (bbl) |
the unit of volume measurement used for petroleum and its products; 1 barrel = 42 US gallons, 35 imperial gallons (approx), or 159 litres (approx): 7.3 barrels = 1 ton (approx): 6.29 barrels = 1 cubic metre. |
BCF (bcf) |
billion cubic feet of natural gas. |
BCM (bcm) |
billion cubic metres. |
BCPD |
barrels of condensate per day (from a gas well) |
BDF |
below drill floor. Depth reference |
Bed |
a geological term describing a stratum (layer of sediments or sedimentary rock) of considerable thickness and uniform composition and texture. |
Benzene |
the simplest aromatic compound with a ring of six carbon atoms; one of the most important feedstocks for the chemical industry. |
BHP |
bottom hole pressure |
Bit |
see drill bit. |
Block |
the subdivision of a nation's exploration and production acreage. Blocks are generally defined in terms of latitude and longitude, at one-degree intervals. |
Block number |
the number assigned to a particular licence block or subdivision thereof in a given national sector of the continental shelf. |
Blowdown |
a method of producing a gas/condensate reservoir by letting the reservoir depressure over time without re-injecting any gas. With this method of production some condensate may condense within the reservoir, where its recovery is no longer a practical proposition. |
Blowout |
the situation that occurs when gas, oil or salt water escapes in an uncontrolled manner from a well due either to a release of pressure in the reservoir rock that the various containment systems fail to check or to the failure of the containment systems during production. |
Blowout preventor (BOP) |
a hydraulically operated wellhead device designed to ensure that a blowout cannot occur. |
BOE (Barrel oil equivalent) |
a term frequently used to compare gas with oil and to provide a common measure for different quality gases. It is the number of barrels of stabilised crude oil which contains approximately the same amount of energy as the gas: for example: 5.8 tcf (of lean gas) approximates to 1 billion boe. |
BOPD (bopd) |
in production terms, the number of barrels of oil produced from a well over a 24 hour period, normally an average figure from a longer period of time. |
Borehole |
the wellbore, with or without casing. See open hole. |
Bottomhole assembly (BHA) |
the lower end of the drill string comprising the drill bit, drill collars, heavyweight drill pipe and ancillary equipment. |
Bottomhole money |
Contribution to a joint-venture well, payable only if a specified horizon is reached. |
Bottoms up |
One complete circulation. When a drilling break is seen it may be decided to circulate 'bottoms up' (ie., all sample out of the hole) prior to proceeding. |
Bourdon gauge |
an instrument for measuring the pressure of steam or other gases. |
Brent blend |
a blend of North Sea crudes, used as an international marker for crude oil pricing. |
Bridge plug |
Packer run into the hole on drillpipe or wireline and left in the hole to seal it. Can be used while the B.O.P. is being changed or a seat for cement when abandoning the well. Some types can be retrieved and reused; others are drilled up after use or abandoned in the hole. |
Btu or British Thermal Unit |
the quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit. The value of a natural gas is governed by its 'Btu value'. |
BTX |
abbreviation of the aromatic hydrocarbons, benzene, toluene and xylene. |
Bunter |
the lowest series of formations laid down during the Triassic Period of geological time; it includes sandstones that sometimes contain hydrocarbon |
Butane |
a hydrocarbon consisting of four carbon atoms and ten hydrogen atoms. Normally a gas, but easily liquified for transport and storage; used in gasolines and for cooking and heating. See also LPG. |
BWPD |
Barrels of water per day |