best estimate

million standard cubic feet per day

two dimensional

proven and probable

Annual Contract Quarterly

Well drilled after the discovery of oil or gas to establish the limits of the reservoir, the productivity of wells in it and the properties of the oil or gas. See also development well

(bbl: barrel; mmbbls: million barrels) a unit of measure for oil and petroleum products equal to 42 US gallons or 35 imperial gallons

billion British thermal units per day

Subdivision of sea area for the purpose of licensing to a company or companies for exploration/production rights. A UK block is 1/30 of a quadrant and is approximately 200-250 sq. km (a quadrant is one degree by one degree.)

Accidental escape of oil or gas from a well during the drilling stage