KNUCKLE JOINT FOR DRILLING INCLINED-DIRECTIONAL AND HORIZONTAL WELLS Russian patent published in 1996 - IPC

FIELD: drilling the gas and oil wells. SUBSTANCE: knuckle joint for drilling inclined-directional and horizontal wells consists of upper sub and curved sub, pins and seal. Curved sub has certain angle of curvature and hinged to upper sub by means of pins that provides for additional angle of inclination due to limited cranking of curved sub relative to upper sub. These angles lie in one plane. To limit free turning of subs relative to each other, they have mutually contacting cylindrical and conical surfaces. During running into well through straight section, angles equalize each other, and when drilling bit is landed on the bottom, the angles are added to form large common angle of deviation of knuckle joint and to increase well angle of inclination at minimum curvature radius. Loss of working fluid through gaps between upper sub and curved sub is prevented by tight seal which is tightly pressed to inner surface of subs. EFFECT: higher efficiency. 2 dwg