DEVICE FOR WELL DRILLING BY DOWNHOLE HYDRAULIC MOTOR Russian patent published in 2003 - IPC

FIELD: equipment for drilling of oil and gas wells; applicable in downhole drill string assembly. SUBSTANCE: device includes hydraulic loader installed between downhole hydraulic motor and drill string and consisting of cylinder connected with drill string and working piston accommodated in cylinder and connected with body of downhole hydraulic motor and mechanism transmitting the reactive torque of downhole hydraulic motor to drill string. Working piston is made with hollow upper and lower rods. Working piston is connected with body of downhole hydraulic motor with help of its hollow lower rod. Cylinder inside has stop forming circular chamber together with working piston, lower rod and bore made in cylinder. Upper part of hollow lower rod has holes. Lower part of hollow lower rod has normally open circulating valve for communication of rod internal cavity with downhole hydraulic motor. Circular chamber is made for communication with annular space by means of safety valve installed in cylinder. EFFECT: provided automatic feed of drill string as drilling bit lowers within interval of hydraulic loader stroke. 2 cl, 5 dwg