Patent ID: 6263986
Filing Date: 2001-07-24
Classification: E21B

Abstract:
A hydraulic drilling jar for use in association with downhole drilling and adaptable for connection between components of a drill string, the hydraulic drilling jar comprising:(i) an outer generally hollow hydraulic housing having an enclosed first end and an open second end, said first end releasably securable to a first component of the drill string;(ii) an inner mandrel assembly having a first end releasably securable to a second component of the drill string and a second end slidably receivable within said open second end of said hydraulic housing thereby forming an internal fluid chamber between said mandrel and said housing, said mandrel assembly slidable within said outer housing from a contracted position to an extended position, said hydraulic housing and said mandrel assembly operatively connecting the first and second components of the drill string;(iii) an anvil portion and a hammer portion, one of said anvil and said hammer portions situated on said hydraulic housing and the other of said anvil and said hammer portions situated on said mandrel assembly; and,(iv) a hydraulic valve received around said second end of said mandrel assembly and within said fluid chamber,wherein upon extension of said drilling jar through the application of a tensile load between said housing and said mandrel, said valve seats against said housing and said mandrel and thereby bifurcates said fluid chamber into first and second portions while pressurizing said first portion of said fluid chamber to place said hydraulic drilling jar in a cocked configuration, such that further extension of said hydraulic drilling jar through the continued application of a tensile load causes said valve to become unseated allowing for rapid de-pressurization of said first portion of said fluid chamber and a resulting rapid further extension of said hydraulic drilling jar with high impact loading of said anvil and said hammer portions.