1.
n. [Drilling]
The total force pulling down on the
hook. This total force includes the weight of the
drillstring in air, the drill collars and any ancillary equipment, reduced by any force that tends to reduce that weight. Some forces that might reduce the weight include friction along the wellbore wall (especially in deviated wells) and, importantly, buoyant forces on the drillstring caused by its immersion in drilling fluid. If the BOPs are closed, any
pressure in the wellbore acting on the
cross-sectional area of the drillstring in the BOPs will also exert an upward force.