Seismic Data Acquisition And Recording PDF Download

This book deals with the optimization technique of seismic data acquisition parameter. Each aspect of acquisition parameter has been discussed in detail. Chapter-one deals with the general technique of seismic data acquisition and common meaning of some of the terms being used in exploration seismic in on land and offshore areas, particularly about characteristics of source & receiver and acquisition techniques. Chapter-two deals with the optimization of Geometrical Parameters i.e. far-offset distance, near-offset distance, group interval, effective array length, foldage, line orientation and line length. Chapter-three deals with the optimization of Source Parameters. Basic goal of optimization is to have required resolution and signal to noise ratio in the acquired data. For explosive source, shot hole depth, charge size and lithology of the medium surrounding the charge are three parameters which decide the source signature. First of all records with different depths below the weathering layer with equal charge size is taken. Signal to noise ratio and peak frequency of the signal at the main zone of interest is computed. Amplitude spectra of different traces at main zone of interest are also compared for all the records. Record giving highest peak frequency and signal to noise ratio corresponds to optimum depth. Now keeping this depth fixed, charge size is varied and record are taken. Again signal to noise ratio, peak frequency and amplitude spectra are compared and a suitable one is selected on the basis of frequency content and signal to noise ratio. In the case of land airgun, Number of airgun, number of pops and air gun patterns are the main parameters, which decide signal to noise ratio. In the case of Vibroseis, sweep length, end frequencies of the sweep and Vibroseis pattern are the main parameters to be optimized in the field. In marine work marine air gun is the widely used marine seismic source. Peak to peak amplitude, primary to bubble ratio (PBR) and bandwidth of the amplitude spectrum are the deciding parameters for selection of source.Chapter-four deals with the Source/Receiver Array Parameters. Effective array length, element's weighting and spacing are the parameters to be optimized on the basis of desired seismic resolution as well as degree of attenuation of coherent noise. Effectiveness of the array is examined by fold-back experiment and f-k diagram.Chapter-five deals with the Recording System & Quality Control. Silent features have been discussed here, which are essential to be adhered in the field so that objective of the survey is achieved.