Drill collar structure of nuclear magnetism logging-while-drilling instrument

Abstract

The invention relates to a drill collar structure of a nuclear magnetism logging-while-drilling instrument. The drill collar structure is provided with a drill collar body with the hollow interior, anantenna is arranged on the outer wall of the drill collar body, a supporting casing pipe is arranged in the drill collar body in a matched manner, the positions, on the two sides of the antenna, of the outer wall of the drill collar body are provided with outer layer magnetic bodies, inner layer magnetic bodies corresponding to the outer layer magnetic bodies are arranged between the periphery ofthe supporting casing pipe and the inner wall of the drill collar body in a spaced manner, the periphery of the drill collar body is provided with a fiberglass outer cover wrapping the outer layer magnetic bodies and the antenna, and the position between the fiberglass outer cover and the drill collar body is filled with grease which cannot be compressed. The inner layer magnetic bodies and the outer layer magnetic bodies are arranged, more magnetic bodies can be arranged to improve the strength of a static magnetic field on the periphery of a probe, the problem that the size of magnetic bodies of a traditional logging instrument is limited can be solved, the fiberglass outer cover is adopted to ensure normal emitting of alternating electromagnetic wave signals and correct receiving of nuclear magnetic echoes, due to filling of the grease which cannot be compressed, the use strength of the fiberglass outer cover can be improved, and the damage of the probe of the logging instrument under the high pressure can be avoided.

Description

technical field [0001] The invention relates to the technical field of nuclear magnetic resonance logging, in particular to a drill collar structure of a nuclear magnetic logging tool while drilling. Background technique [0002] NMR logging while drilling is a new logging technology suitable for open-hole wells. It is currently the only logging method that can directly measure the seepage volume characteristics of free fluid (oil, gas, water) in any lithological reservoir. The logging-while-drilling nuclear magnetic resonance instrument is mainly composed of probes, electronic circuits, power supplies and control acquisition and processing software. The probe includes a magnet and an antenna, which is the core of the whole system and a symbol of the development of nuclear magnetic resonance logging tools. The magnet generates a static magnetic field, and the antenna is used to emit an alternating magnetic field perpendicular to the direction of the static magnetic field an...

AI Technical Summary

Problems solved by technology

The strength of the instrument sealing system and the protective cover of the probe is the key point of the drill collar structure. During the downhole drilling process, the pressure of the mud and drilling fluid is relatively high. Once the instrument sealing system or the protective cover of the probe is damaged, the probe will be damaged and cause great losses.

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