Study on Thermal Energy Conversion Theory in Drilling Process of Coal and Rock Mass with Different Stresses

Abstract

In view of the problem that the evolutionary mechanism of bit temperature during the drilling process is still unclear and the influencing factors are complex, this paper analyzes the causes of heat generation and the factors of heat production when the drill bit interacts with the coal and rock mass. Considering the stress field distribution of coal and rock mass and the dynamic characteristics of drilling, a three-dimensional mechanical structure model of bit drilling is established in this paper, based on the energy conservation theory and introducing the friction heat micro-distribution mechanism. The corresponding relationship between coal stress and the bit temperature variation rate is obtained in this paper. Therefore, the temperature rise condition model and the coal stress identification model can be verified, combined with the existing experimental data. The result shows that the temperature of bit drilling is affected by factors such as bit geometry and drilling parameters, as well as the strength and stress state of the coal and rock. Without considering other factors, the rate of increase in bit temperature is proportional to the stress of the coal and rock mass. Based on the research results, the temperature rate of the drill bit can be used as an index to identify the stress areas of coal and rock mass. Research results provide a theoretical basis for the identification of high-stress risk areas in coal mines.

Process Monitoring in Heavy Duty Drilling Rigs—Data Acquisition System and Cycle Identification Algorithms

“…Therefore, the simultaneous observation of the acoustic data, voltages, currents and other signals available from the on-board data acquisition systems-e.g., bailing water pressure or temperature [22]-should help to better understand some hidden dynamical processes in the machine, leading to higher performance via its automation and control.…”

Change of the Properties of Steel Material of the Roller Cone Bit Due to the Influence of the Drilling Operational Parameters and Rock Properties

“…An analysis of influence factors on increasing temperature during drilling on the drill bit was established by bit geometry and drilling parameters, as well as the strength and the stress state of the rock [24].…”