The Experimental Analysis on Influencing Factors of P-Wave Velocity in Red Sandstone

Due to the internal structure of red sandstone is loose, the influence factors of acoustic velocity are variety, it is necessary to make a quantitatively research on the influence factors. With the aid of the ultrasonic testing for the rock, p-wave velocity of red sandstone decreased with the increase of porosity under the condition of no coupling medium, when the porosity exceeded a certain value, its internal pores and fractures had a great influence on wave velocity. When the density of red sandstone was greater than 1.82 g/cm3, wave velocity changed little, while the density was less than 1.82 g/cm3, wave velocity decreased rapidly. Under water-solid coupling condition, the change of wave velocity and porosity had no obvious regularity, part of the specimens’ wave velocity decreased a bit, while some specimens’ wave velocity were slightly higher, but the amplitude were small; Under oil-solid coupling condition, longitudinal wave velocity changed significantly, the biggest percentage of increase was 46.3%, the average was 33%.