What is a wavelet? From a seismic processor's point of view, a wavelet is one of the basic building blocks used to construct the seismic models on which seismic-processing methods are based. In the various processing steps, the wavelets are removed from the seismic data to yield the final sections. Correct estimation and/or measurement of the wavelets allows the good results that are expected in any exploration program. The wavelet is a basic concept, and good wavelet estimation is fundamentally important in exploration geophysics.
The seismic method is an instrument for remote detection that uses seismic traveling waves to delineate the subsurface structure of the earth. An exploration geophysicist illuminates the earth's subsurface by an energy source that generates those seismic waves. In a 3D earth, the waves travel in all directions, but to keep the present discussion simple, we consider the case of only vertically upgoing waves and vertically downgoing waves.
Subsurface rock layers transmit and reflect the seismic waves, and seismic theory and practice deal with those traveling seismic waves. The simplest example of a traveling wave is a primary reflection. A primary reflection consists of the downgoing path from the source to the reflection horizon and the returning upgoing path from the reflector to the receiver. A multiple reflection is an event that bounces back and forth among various interfaces as it proceeds on its trip. Directional sensors can be used to record seismic waves, but usually the receiver is either a hydrophone (for exploration at sea
Figures & Tables
Digital Imaging and Deconvolution: The ABCs of Seismic Exploration and Processing (SEG Geophysical References Series No. 15), covers the basic ideas and methods used in seismic processing, concentrating on the fundamentals of seismic imaging and deconvolution. Most chapters are followed by problem sets. Some exercises supplement textual material; others are meant to stimulate classroom discussions. Text and exercises deal mostly with simple examples that can be solved with nothing more than pencil and paper. The book covers wave motion; digital imaging; digital filtering; various visualization aspects of the seismic reflection method; sampling theory; the frequency spectrum; synthetic seismograms; wavelets and wavelet processing; deconvolution; the need for continuing interaction between the seismic interpreter and the computer; seismic attributes; phase rotation; and seismic attenuation. The last of the 15 chapters gives a detailed mathematical overview. Digital Imaging and Deconvolution, nominated for the Association of Earth Science Editors award for best geoscience publication of 2008–2009, will interest professional geophysicists, graduate students, and upper-level undergraduates in geophysics. The book also will be helpful to scientists and engineers in other disciplines who use digital signal processing to analyze and image wave-motion data in remote-detection applications. The methods described are important in optical imaging, video imaging, medical and biological imaging, acoustical analysis, radar, and sonar.