DOWNHOLE HYDRAULIC JACK TO REMEDY SEIZURES Russian patent published in 2002 - IPC

FIELD: drilling and repair of oil and gas wells. SUBSTANCE: downhole hydraulic jack is designed to remedy seizures and to remove tubing, packers and other seized objects. Body of power cylinders is connected to hydraulic anchor. Shaft of hydraulic jack is directly linked to fishing string. At the bottom shaft is joined to seized object through catch- all. Adjustable relief valve is installed between hydraulic anchor and hydraulic cylinders. In addition to main effort developed by hydraulic cylinders additional axial load from hoisting installation can be given to seized object through fishing string. Collet gripper fixes body of hydraulic jack in upper position relative to shaft while hydraulic jack is recharged. Design of hydraulic jack makes it feasible to monitor progress of removal of seized object, to conduct connecting and disconnecting operations with catch-all with seized object and to reciprocate it. Adjustable relief valve secures switching on of armature, reliable engagement of casing string without sliding and wear-out of dies of anchor. EFFECT: raised functional efficiency an reliability of downhole hydraulic jack. 1 cl, 3 dwg