Automatic measurement method of drilling-cuttings of boreholes in the coal seam and test study

YIN Yanchun; ZHENG Wuwei; ZHAO Tongbin; REN Wentao; ZHANG Wei; ZHAO Zhigang

doi:10.12438/cst.2022-2006

Abstract：Drilling-cutting method is a commonly used coal bump risk detection method in coal seams.The efficient and accurate acquisi-tion of the quality of drilling-cuttings is a technical difficulty in engineering site,which could directly affect the risk detection efficiency and results.Based on the discharging characteristics of drilling-cuttings and the principle of fluid quality weighing,an automatic measur-ing device for drilling-cuttings suitable for different diameter boreholes is developed.This device consists of cuttings collecting unit,weighing unit,data processing system and fixing unit.It can measure the quality of the drilling-cuttings according to the flow-quality of drilling-cuttings discharged from the borehole and the calibration function.The measurement accuracy of this method is verified by labor-atory test and field test.Research shows that the drilling process and drilling pipe installation process can be easily identified based on the drilling cuttings'flow quality-time curve.The accumulated flow-quality of drilling-cuttings per meter has positive linear correlation with its actual quality,and the calibration function is related to the device measurement parameters,such as the dip angel of the weighing slide-way and the sampling frequency.Compared with the conventional weighing method,when measuring the drilling-cuttings by using the automatic measurement device,the maximum measurement error of the laboratory test is less than 6.5%,and the average error of the field test is 5.13%,while the data with error less than 10%account for 86.91%.The device measure parameters and the engineering factors,such as drilling-cuttings flow velocity and particle size,have little effect on the measurement accuracy.In the construction of conventional-diameter drilling-cutting borehole,the drilling pipe installation process time is reduced by 25.16%,and the construction efficiency is in-creased by 11.84%.The distribution law of drilling-cuttings in the shallow part of the large-diameter destressing borehole is consistent with that of the conventional-diameter drilling-cutting borehole,and the distribution of drilling-cuttings in deeper roadway side can be ob-tained.The proposed automatic measurement method of drilling-cuttings can improve the construction operability of large-diameter drilling-cutting method,and can realize the synchronous operation of pressure relief and drilling-cuttings measurement.