HYDROMECHANICAL JAR Russian patent published in 2000 - IPC

FIELD: oil and gas producing industry, particularly, percussion devices applicable in releasing of stuck pipes in vertical, inclined and horizontal wells. SUBSTANCE: jar has body which middle part is made in the form of cylinder filled with working fluid. Hollow rods with seals are connected with each other by piston which separates cylinder into above- and under-piston hollows. Two check valves are built in piston. One of pistons is installed for passing the working fluid from above-piston hollow to under-piston hollow. The other piston is installed for passing the working fluid from under-piston hollow into above-piston one. Throttling nozzle is installed in one of check valves. Upper and lower transverse partitions separate cylinder from body upper and lower parts. Tie-rod is installed in body upper part and rigidly connected to hollow rod. Cylindrical insert is installed in piston for its radial motion. There are upper and lower pairs of anvils. Cylinder upper and lower parts have circular grooves. At inlet of grooves, longitudinal recesses are found. EFFECT: reliable in operation, capable in delivering blows in direction of wellhead and towards hole bottom, and provided well flushing. 5 cl, 2 dwg