bumper sub

bumper sub

[′bəm·pər ‚səb]
(petroleum engineering)
A motion compensator that maintains constant weight on the drilling bit during vertical motion of a floating offshore drilling rig and also provides a jarring action to remove heavy objects in the borehole.
References in periodicals archive ?
Global Rentals, with main operations in Norway, a rental and service facility in the Netherlands and a sales office in Dubai, provides downhole drilling tools including the Megaton drilling jars, fishing jars, energizers, shock tools, bumper subs, drilling safety joints and under reamers.
Hannah said in addition to the drilling rigs companies can use the site explore and compare a diverse selection of drilling tools such as anderdrifts, reamers, shock tools, variable gauge stabilizers, drill collars, andergauges as well as drilling jars, check valves, safety valves, bumper subs and drillstring components and related accessories for all well, material, deephole and precision applications.