GEROTOR HYDRAULIC DRIVE Russian patent published in 2007 - IPC E21B4/02 

FIELD: oil and gas well drilling equipment, particularly fluid rotary type drives.

SUBSTANCE: hydraulic drive comprises hollow body, multistart screw gerotor mechanism, spindle connected to rotor by drive shaft and fastened to drilling bit. Hollow body has threaded adapter to connect thereof with drilling string. Hollow body also comprises a number of threaded subs to connect thereof with spindle. Minimal weak sectional area of threaded adapter walls determined from the side of adapter connection with hollow body and/or that of hollow body at threaded adapter connection is 0.55-0.85 of minimal weak sectional area of threaded adapter walls determined from the side of adapter connection with drilling string and/or drill pipe and/or another threaded member located from drilling string side. Inner channel of threaded adapted is provided with fishing end. Threaded piston is located inside threaded adapter. One piston end is connected with rotor, another end is provided with fishing ring. Fishing ring diameter exceeds that of adapter channel in fishing end plane. Fishing ring end facing fishing end of threaded adapter has slots. Slot throat area F₁ determined when fishing ring extensions is brought into contact with fishing end of threaded adapter and area F₂ defined between inner channel of threaded adapter and threaded piston in fishing end plane is determined as F₁=(0.618÷0.866)·F₂.

EFFECT: possibility of gerotor hydraulic drive with spindle and drilling bit lifting from well when threaded connection thereof with drive body is broken.

3 cl, 4 dwg