A sulphate of barium used to add weight to drilling fluids.
Unit of measurement consisting of 42 gallons of oil or other fluid.
A type of clay often added to drilling fluid because of its swelling properties when added to water.
The cutting part of the drilling equipment.
When downhole pressure overcomes the weight of drilling fluid and rises in a well to the surface out of control. An underground blowout is where the overpressuring enters another formation higher in the well, but before it reaches the surface.
A system of valves and rams set in a well which can be closed successively to counteract the uncontrolled rise of oil or gas from a reservoir below.
Barrels of oil equivalent. A figure used when expressing the combined volume of oil and gas reserves.