Seismic Wave and Rock-Fluid Properties

Abstract

Seismic rock physics is study of seismic response of rock and fluid properties, used essentially to help predict reliably the lateral and vertical variation in rock properties in the subsurface from seismic data. This would entail knowing basics about seismic wave and its propagation in the earth and the different rock and fluid properties that impact seismic properties. Seismic waves are elastic waves and suffer loss of energy of different kinds while propagating through rock layers having different rock properties in the earth. The propagation mechanisms, the losses and their geologic significance are described. The intrinsic seismic properties are the amplitude and velocity which are influenced by properties of rocks through which the wave travels. The elasticity and density of rocks primarily determine the seismic amplitude and velocity, though several other rock and fluid properties such as porosity, texture, fractures, fluid saturation, viscosity and factors such as pressure and temperature also affect the seismic properties. The microstructure of rock, its elastic, physical and geomechanical properties and their seismic responses, known as seismic rock physics studies are deliberated. Descriptions of homogeneous, heterogeneous, isotropic and anisotropic rocks and seismic anisotropy, Gassmann’s equation and fluid saturation, normal, abnormal and pore pressures are dealt to elaborate the seismic rock physics studies. Seismic rock physics modelling (RPM) and mechanical earth modelling (MEM), their utilities in seismic rock physics application along with limitations are mentioned.