Analysis of the Dependence between Acoustic and Physico-Mechanical Properties of Terrigenic Rocks

Abstract

During the entire development of an oil and gas field, it is necessary to carry out a complex of various studies aimed at identifying the parameters of the productive layer. One of such studies is the analysis of core material, as a result of which the following parameters of the rock are determined: porosity, permeability, Young's modulus and others. The listed characteristics must be taken into account when building a geological and hydrodynamic model of a field. In addition to these parameters, the strength properties of the rock should be determined, since they are necessary in the design of the wellbore. Such characteristics can be obtained by conducting research in specialized laboratories. This is not always possible due to various reasons. A number of studies confirm the fact of the relationship between the acoustic properties of a rock (the velocity of the longitudinal and transverse waves) and the strength characteristics. The acoustic properties of the rock must be taken into account when interpreting the acoustic logs of the wells, which allows to reveal the distribution of rocks along the wellbore. Based on the velocities of ultrasonic waves propagation, it is possible to calculate the elasticity dynamic modulus, which let assess the tendency of the rock skeleton to compaction as a result of the effective stress action. Therefore, the determination of the rock acoustic properties is necessary when planning the development of a field and its implementation. The results of laboratory studies aimed at establishing the relationship between the strength and acoustic properties of rocks are presented. During the experiment, the dynamic Young's modulus was also determined and its relationship with the speed of ultrasonic waves propagation was revealed. As a result of laboratory studies, empirical dependences of the ultimate strength in volumetric compression (σс), elasticity dynamic modulus (E ) and the velocity of transmission of longitudinal (vp) and transverse waves (vp) were obtained. An assessment of the obtained values was given over the entire measurement range.