Drilling string shock-absorbing tool

DETAILED DESCRIPTION The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows: 1.
A tool for use in a drill string adapted to circulate pumped drilling fluid to drill a well bore, said tool having utility for absorbing shock loading arising from axial movement of the drilling bit, said tool comprising: telescopically arranged tubular parts comprising an outer barrel and an inner mandrel received in the barrel, said parts forming an annular space between them which includes a deformable element chamber, said parts being movable longitudinally relative to each other; means at the outer ends of the parts for threadably connecting them into the drill string whereby the tool forms part of the drill string; means carried by the parts for limiting their relative longitudinal movement; said parts comprising means connecting them so that they rotate together but may move longitudinally relative to each other; solid resilient deformable element means disposed in the chamber and extending substantially throughout its length, said element means having a spring rate of less than 100,000 pounds per inch and being substantially out of contact with the adjacent barrel or mandrel side wall which is movable by the axial movement of the drilling bit, whereby said element means, in use, experiences throughout its length substantially the total axial shock load; a pair of opposed compression means, one such means being carried by the mandrel and extending into the chamber adjacent one end thereof, the other such means being carried by the barrel and extending into the chamber adjacent the other end thereof, said compression means being operative to act against the ends of the element means; a body of operating liquid disposed in the space together with the element means; seal means disposed in the space above and below the chamber for sealing that portion of the space between said seal means against the entry of well bore drilling fluid thereinto; and means for pressurizing the operating liquid to substantially equalize it with the pressure of the circulated pumped drilling fluid internal of the tool