Independent one-way acting hydraulic jar sections for a rotary drill

Abstract

First and second separate one-way acting hydraulic jar sections each include inner and outer telescopically arranged tubular members with means for connecting one end of each the inner and outer tubular members of each jar section in the drill string. Spaced seal means between the inner and outer tubular members form a chamber in each jar section for confining hydraulic operating fluid. Hydraulic jar means are formed by cooperating means on the inner and outer tubular members within each operating fluid chamber. The cooperating means is spaced axially and disengaged in each fluid chamber when the drill string is in tension and compression during rotary drilling operation to inhibit damage and wear thereto. The hydraulic jar means in the first jar section is constructed to deliver an up jar and the jar means in the separate second jar section is constructed to deliver a down jar to the drill string. Drive means in a sealed chamber in each jar section connect the inner and outer tubular members of each jar section to allow relative longitudinal movement while preventing relative rotation therebetween. Means to equalize pressure adjacent one end of each of the chambers with the pressure in the well bore is provided in each jar section, which accommodates relative longitudinal movement of the inner and outer tubular members of each jar section for selectively creating an up or down jarring force independently of the well bore pressure.