Hydraulic drilling jar

Hydraulic jar apparatus adapted for use in a drilling string comprising:

• telescopically disposed mandrel and housing members adapted for relative movement between extended and retracted relative positions;
• slidably engaged means on said members for preventing relative rotation;
• first impact surfaces on said members adapted to be brought against one another by telescoping movement to said extended position, and second impact surfaces on said members adapted to be brought against one another by telescoping movement to said retracted position;
• first means for restraining movement of said mandrel member toward said extended position including first restriction means on said housing member having an internal bore and seal means in said internal bore, piston means on said mandrel member sealingly slidable within cylinder means on said housing member, said piston means being axially spaced from said first restriction means to provide a first annular, oil-filled pressure chamber, first enlarged diameter surface means on said mandrel engageable with said seal means in said internal bore of said first restriction means for preventing leakage therebetween, and first flow metering passage means in said first restriction means for restricting the flow of oil from said first pressure chamber therethrough as said piston means is moved toward said first restriction means, said first restraining means being effective to delay movement of said mandrel member toward said extended position until said first surface means disengages from said seal means;
• and second means for restraining movement of said mandrel member toward said retracted position including second restriction means on said housing member having an internal bore and seal means in said internal bore, said piston means being axially spaced from said second restriction means to provide a second, annular oil-filled pressure chamber, second enlarged diameter surface means on said mandrel member engageable with said seal means in said internal bore of said second restriction means for preventing leakage therebetween, and second flow metering passage means in said second restriction means for restricting the flow of oil therethrough as said piston means is moved toward said second restriction means, said second restraining means being effective to delay movement of said mandrel member toward said retracted position until said second surface means disengages from said seal means in said internal bore of said second restriction means.

A hydraulic jar comprising:

• inner and outer telescopically arranged tubular members that are movable longitudinally relative to each other between limit positions at which jarring actions occur;
• upper and lower movable seal means between said members for defining an oil-filled chamber therebetween;
• piston means on said inner member engaging cylinder means in said outer member for dividing said chamber into upper and lower portions, said upper portion including an upper high pressure section and an upper compensating section, said lower portion including a lower high pressure section and a lower compensating section;
• first restriction means on said inner and outer members between said upper high pressure section and said upper compensating section for restricting the flow of oil from said upper high pressure section to said upper compensating section as said piston means moves upward in said cylinder means in response to said relative movement in one direction, said first restriction means becoming inactive after a predetermined amount of said longitudinal relative movement has occurred;
• and second restriction means on said inner and outer members between said lower high pressure section and said lower compensating section for restricting the flow of oil from said lower high pressure section to said lower compensating section as said piston means moves downward in said cylinder means in response to said relative movement in the other direction, said restriction means becoming inactive after a predetermined amount of said longitudinal relative movement has occurred.

A hydraulic well jar comprising:

• a mandrel member having an enlarged diameter valve head and piston means spaced from said valve head;
• a housing member having cylinder means therein, said piston means engaging said cylinder means to form a high pressure chamber adapted to be filled with hydraulic oil;
• restriction means on said housing member having an internal cylindrical bore;
• a high pressure seal means in said bore, said mandrel member extending though said bore, said piston means being freely movable toward said restriction means until said valve head engages said high pressure seal means;
• and metering means included in said restriction means through which said oil must flow as said piston means continues to move toward said restriction means, said metering means providing a high restriction to such flow until said valve head disengages from said high pressure seal means to provide a bypass around said restriction means.