| 摘要 |
<p>. An elongated borehole logging instrument includes a permanent magnet linear reciprocating motor. The motor powers a sliding sleeve which has attached to its outer perimeter a series of reversible vanes. The vanes engage the mud cake or the borehole wall and thus generate a force opposite to the direction of the vane slant. The motor has a stationary electromagnetic field comprised of a plurality of coils connected to the control electronics. The floating outer sleeve has permanent magnets all oriented in the magnets are either repulsed or attracted to thus generate a reciprocating motion which transferred to the vanes moves the tool up or down, depending upon the position of the reversing actuator. The control electronics is responsive to the difference between the velocity of the well logging instrument, functionally related to its acceleration, and the velocity of the well logging cable at the earth's surface. In an alternative embodiment, a friction reduction agent is ported into the borehole in response to the velocity difference. In other alternative embodiments, the velocity of the well logging instrument is compared with the velocity of the well logging cable at the earth's surface to control the cable hoist drum and thus avoid the risk of overrunning the well logging instrument with too much cable.</p> |
