| 摘要 |
A modular measurement while drilling sensor assembly is presented. A typical cross-over assembly for mating with a measurement while drilling (MWD) tool is connected to a typical positive displacement mud motor (e.g., a Moineau motor). A modular sensor assembly comprises two portions, an upper drive shaft portion which includes a flexible shaft connected to the motor and a lower sensor portion and supported by a radial bearing. The lower end of the flexible shaft is connected to a hollowed shaft which extends beyond the lower end of the upper drive shaft portion and which is supported by a radial bearing. The lower sensor portion has a central channel extending longitudinally therethrough, with the lower portion of the hollowed shaft extending through this channel. The sensor portion may comprise any type of MWD sensor, however the present invention is preferably used with sensors (e.g., formation evaluation sensors) that benefit from obtaining measurements close to the bit. The lower end of the hollowed shaft is supported with a radial bearing and connected to a flexible shaft of an adjustable kick off assembly connected to the sensor portion. The adjustable kick off assembly allows the introduction of a kick off angle, generally between 0 DEG and 3 DEG , in the assembly. The adjustable kick off assembly is connected to a typical bearing pack assembly. The lower end of the bearing pack assembly is typically connected to a drive shaft, a bit box and then the bit.
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