| 摘要 |
<p>A cushion sub for absorbing both axial and torsional vibration in modern drilling techniques. The cushion sub includes an outer casing connectable at one end to a section of a drill string, usually the upper section being actually the output of the rotary drive, and an inner piston reciprocally mounted in a cylinder within the casing, the piston has a shaft projecting from the other end of the casing connectable to another section of the drill string. The cylinder includes a first cushion device at opposite ends thereof for engagement by the piston to absorb axial vibrations and thereby prevent their transmission between the piston and the cylinder. A spline type connection prevents relative rotation between the piston and the cylinder. The cylinder is mounted for arcuate turning within the casing, but the cylinder has vanes which are interposed between vanes fixed to the casing, and elastomeric material between the vanes of the cylinder and the vanes of the casing absorbs torsional vibrations being transmitted between the cylinder and the casing. An outer surface of the cylinder may be spaced radially inward from an inner surface of the casing to form a closed chamber therebetween containing the interspaced vanes and the elastomeric material between the vanes. The elastomeric material is preferably formed in situ as an integral mass in the chamber by pouring the elastomeric material in a fluid state into the chamber. The cushion sub is of a compact nature with long wear characteristics and is capable of handling the types of forces experienced in advanced drilling techniques and preventing the torsional and axial vibrations developed downhole from being transmitted to the rotary drive.</p> |
