Study on Vitrification of Granite Surface by Laser Scanning

With rising energy demand, oil and gas drilling activities are increasing. Laser drilling has great application value in the energy field and is expected to realize the manufacture of downhole in-situ glass casing to replace traditional metal casing, resulting in time and money savings for oil and gas drilling projects. The stable formation of laser irradiation rock vitrification is a key factor in achieving glass casing. In this study, the influencing factors and mechanisms of laser ablation granite vitrification are investigated based on laser scanning granite experiments, combined with phase detection and numerical simulation. The results show that after laser scanning, the constituent minerals of granite melt and fragment according to the ease of melting, and part of the surface is transformed into dark glass. The high-speed airflow can effectively remove rock debris and dust, improve the laser efficiency, and increase the adhesion of rock glass. Granite is susceptible to temperature fracture, and its low scanning speed and airflow auxiliary conditions favor the formation of vitrification. In practical engineering applications, the temperature action of the rock can be controlled via the scanning speed and auxiliary high-speed airflow to form stable rock glass, and create an in-situ vitrification well wall that firmly covers the hard rock surface. This study focuses on the vitrification mechanism of laser-acting rocks, and provides an important reference for expanding the engineering application of laser drilling.