Experimental Study on Tube Wall Temperature Measurement During Coring Tube Sampling Process

To determine the refrigeration dosage in frozen coring technology, the temperature of core tube wall during coring process is measured and recorded by self-made temperature measuring device. The temperature change of core tube wall is analyzed, and the friction heat situation between drill bit and core tube wall and coal seam is studied. The results show that the core tube wall undergoes three stages, slow temperature rise, rapid temperature rise and slow temperature drop. With the increase of the sampling depth, the maximum temperature of the core tube wall increases. The highest temperature in this test occurs in the coal sample collection process when the core depth is 30 m, and the temperature is 98.32 ℃. At the same core depth, the time required for drilling is less than that required for withdrawal, and the heating rate during drilling is higher than the cooling rate during withdrawal.