Invesitgation of the thermo physico-mechanical and drilling characteristics of sandstone in Zonguldak hard coal basin

Abstract Effect of temperature on physico-mechanical properties is an important research topic for engineering applications such as underground coal gasification, exploitation of deep oil and gas resources, extraction of geothermal energy and burial of nuclear waste. This paper aims to investigate the variation of physico-mechanical and drilling properties of sandstones from the Zonguldak Hardcoal Basin at different temperatures (from room temperature to 600 °C). The results show that with the increase in the temperature of the sandstone, the geomechanical parameters and leeb hardness properties decrease, while the drilling rate index and porosity properties increase. Especially, the geomechanical properties of sandstone decrease sharply above 500 °C as the critical temperature of the rock. The average geomechanical properties (uniaxial compressive strength, tensile strength and Young modulus) and Leeb hardness values decreased by %35.3, 30.0, 50.3 and 14 respectively when the sandtone samples heated the 600 °C. On the other hand, the drilling rate index increased by 24.14% and the porosity increased by 470 times compared to its initial value at room temperature. Based on the findings of the present study, statistical analysis (correlation analysis) were revealed between rock physico-mechanical and drilling properties of sandstone and temperature. In the light of this fact, obtained results show that is of great importance to study the changes in the physico-mechanical and drillability properties of the rock after the heating process