The Influence of Fracturing of the Rocks and Model Materials on P-Wave Propagation Velocity: Experimental Studies

Abstract

It is shown that rigidity of the medium is a more strain-sensitive parameter than rock density for the elastic wave velocity with the increase in the depth. For assessing the effect of intergrain and fracture porosity, the ratio (in percent) of the measured P-wave velocity in the rock to the velocity in the solid matrix—the “normalized velocity”—is used. The results of the experimental studies have shown that the effect of fractures (faults, rock joints) and intergrain porosity on the propagation velocity of the elastic P-waves is different. The increase in fracture porosity more strongly reduces the P-wave velocity than the increase in intergrain porosity of identical magnitude. It is shown that the propagation velocity of the elastic P-waves in the rocks and model materials depends on the presence and number of cracks (fractures). The possibility of selective assessment of intergrain and fracture porosity in reservoir rocks of the oil and gas fields during their development is demonstrated.