A comprehensive analysis on the relationships between elastic wave velocities and petrophysical properties of sedimentary rocks based on laboratory measurements

摘要

This paper is an attempt to find the interdependence existing between petrophysical properties and ultrasonic wave velocities. Porosity and permeability, apart from other properties, are the two fundamental physical properties of rock responsible for storing and producing hydrocarbon. Understanding the elastic properties of such rocks is essential in developing a deep understanding about the rock and fluid models that describe the seismic response to realistic hydrocarbon reservoirs under different environmental conditions. Therefore, in this study, a detailed state-of-the-art review of the existing association between compressional and shear wave (also known as P wave and S wave) velocities (Vp and Vs) and different petrophysical properties (porosity, density, permeability, water absorption and clay content) has been summarized for carbonate and sandstone rock types of different regions. The relationships discussed are based on datasets measured in laboratory by various researchers under ambient conditions. An effort is made to propose a general trend (global trends) for porosity versus Vp and bulk density versus Vp, which is independent of the type of datasets. However, it is clear that trends do exist, but the prediction is difficult. The empirical relationships derived by various researchers are valid only to the particular dataset for which the relationship was derived. The influence of other factors like mineralogy, rock framework, pore geometry has not been studied by the researchers in their respective studies. Nevertheless, these relationships and correlations can be useful in hydrocarbon exploration industry where direct measurements may not be possible. Moreover, an accurate reservoir description can only be achieved by the integration of geological, petrophysical and geotechnical data.