Dariusz Knez / AGH University of Science and Technology；Drilling and Geoengineering Department
Mohammad Ahmad Mahmoudi Zamani / AGH University of Science and Technology；Drilling and Geoengineering Department
One of the most fundamental parameters in the poroelasticity theory is Biot’s coefficient. This parameter indicates the role of pore fluid in the porous rocks against the outer applied stresses. In this research, a dynamic approach has been utilized to compute the dynamic Biot’s coefficient of sandstone samples taken from a mine in Kielce, Świętokrzyskie, Poland. To do this, a number of seven sandstone samples were prepared in the laboratory, and the corresponding dry mass, wet mass, and porosity were recorded. Then, the samples were subjected to hydrostatic stress in an acoustic wave propagation apparatus under undrained condition. In this case, the undrained bulk modulus of each was measured. Then, the undrained condition was changed to the drained one, and hence, the corresponding drained bulk modulus was measured for each specimen. Afterward, using the available poroelastic equations between the undrained and drained bulk moduli, the value of dynamic Biot’s coefficient was calculated. Through this, an empirical correlation was developed for dynamic Biot’s coefficient. Our findings illustrated that this coefficient decreases logarithmically with the hydrostatic stress. Moreover, the magnitude of dynamic Biot’s coefficient varied between 0.52 and 0.60 which is quite reasonable for sandstone rocks. The extracted empirical correlation can be used for the potential future works in which the role of the poroelastic parameters are important for consideration.