Abstract

In view of the problems that the existing gamma logging instruments in coal mines can only carry out static fixed-point measurement and are not suitable for rotary drilling, this paper, based on the analysis of the characteristics of measurement while drilling in coal mines and the principle of gamma logging, designs and realizes the dynamic gamma azimuth instruments for mines by means of power line carrier, rotation positioning and gamma measurement technology, which can measure the intensity of natural gamma ray in two directions around the borehole in real time, effectively reflect the changes of different radioactive strata, and guide the geosteering while drilling in coal mine.

Highlights

  • At present, the most direct and effective method of gas control is to drill and extract along the coal seam

  • Some researchers have developed measurement instruments while drilling based on natural gamma in coal mine, which can realize all-round natural gamma measurement and multi-directional static azimuth gamma measurement while drilling, and provide some reference for directional drilling trajectory control

  • The gamma detector is installed on the framework of the azimuth gamma logging tool while drilling, and the scintillation crystal and photomultiplier tube are shielded by tungsten-copper-nickel alloy

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Summary

Introduction

The most direct and effective method of gas control is to drill and extract along the coal seam. Different coal-bearing strata have different changing ranges of natural gamma. The characteristics of natural gamma difference of different coal-bearing strata can be fully utilized to identify lithology in combination with the situation of slag returning from the orifice, so as to guide the directional drilling construction, realize the identification of drilling strata and improve the control efficiency of drilling trajectory [1,2,3]. Some researchers have developed measurement instruments while drilling based on natural gamma in coal mine, which can realize all-round natural gamma measurement and multi-directional static azimuth gamma measurement while drilling, and provide some reference for directional drilling trajectory control. With the change of directional drilling technology from sliding directional drilling technology to complex rotary directional drilling technology, the instrument cannot meet the requirements of natural gamma dynamic measurement while drilling in complex rotary directional drilling [4-6]

Principle of azimuth gamma while drilling
Overall instrument design
Design of carrier module
Design of Power module
Design of main control board
Gamma detector
Instrument structure design
Experiment
Findings
Conclusion

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