首页|The influence of laser irradiation parameters on thermal breaking characteristics of shale
The influence of laser irradiation parameters on thermal breaking characteristics of shale
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NSTL
Mechanical drilling is facing increasing challenges in exploiting energy stored in deep and hard formations. Laser irradiation has emerged as a novel drilling method with a large potential. The mechanisms of laser irradiation for rock removed consist of melting, evaporation, and splashing. In this study, the characteristics of circumferential strain, temperature, hole size, and modified specific energy of shale rock were studied under laser irradiation with different powers, frequencies, and focal lengths. As indicated from the results, the hole diameter showed a significant positive relationship between laser power and laser frequency, whereas the modified specific energy displayed a negative one. The hole depth increased with the increase of the laser power and the decrease of the laser frequency. The focal length significantly impacted the thermal breaking effect exerted by laser irradiation. The hole diameter was minimum at the focal length of 4.0-4.2 mm. With the increase in the focal length, the hole depth increased from 28.6 mm to 35.5 mm and then declined to 21.1 mm, whereas the modified specific energy decreased from 324 kJ/g to 95 kJ/g and then increased to 108 kJ/g. The cracks in irradiated shale were identified under the scanning electron microscope. This study has a certain guiding significance to break rock for drilling deep hard reservoirs.
Laser irradiationRock breakingModified specific energyThermal destructionHole size
Haizeng Pan、Yi Hu、Yong Kang
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Hubei Key Laboratory of Waterjet Theory and New Technology, Wuhan University, Wuhan, 430072, China
NSTL
