Surface roughness estimation and rock type identification by ultrasonic and optical techniques

In the present-day practice of geocontrol, the structure and behavior of rock masses are estimated using various geophysical methods, in particular, ultrasonic sounding and logging. Such measurement techniques require dry contact at the rock–transducer interface, which essentially reduces reliability of the information obtained. Enhancement of the acoustic approaches to the adjacent rock mass analysis is possible via their complexing with the contactless optical scanning of well walls. This article describes the experimental observation of various rock types using the dedicated optical electronic modules. It is shown that surface roughness of rocks can be determined from the analysis of the reflected light intensity, and the main message-bearing parameters in this case can be the coefficient of variation and coefficient of correlation of signals recorded along the same profile by two photosensors. Furthermore, it is experimentally proved that surface roughness has influence on ultrasonic pulses, which consists in reduction in energy and in spectrum of signals. It is proved that the energy of the pulses can be adjusted by changing the pressing force of the transducer in the pressure range from 0 to 2.5 atm. It is also possible to identify rock types from the analysis of the reflected light intensity at different wave lengths, which can be used to improve reliability of ultrasonic logging of adjacent rock mass composed of rocks having similar acoustic properties.

Nikolenko P. V., Zaitsev M. G. Surface roughness estimation and rock type identification by ultrasonic and optical techniques. MIAB. Mining Inf. Anal. Bull. 2022;(3):5-15. [In Russ]. DOI: 10.25018/0236_1493_2022_3_0_5.

The study was supported by the Russian Science Foundation, Project No. 21-77-00046.

P.V. Nikolenko¹, Cand. Sci. (Eng.), Assistant Professor, e-mail: p.nikolenko@misis.ru,
M.G. Zaitsev¹, Graduate Student,
¹ National University of Science and Technology «MISiS», 119049, Moscow, Russia.

P.V. Nikolenko, e-mail: p.nikolenko@misis.ru.

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