The Seismic Processing Tools
From mid 1950s till mid 1960s a jump in the seismic data processing took place. Within this interval, the analogue magnetic-tape recording and processing, followed by the introduction of digital technique, were introduced.
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The Seismic Processing Tools
From mid 1950s till mid 1960s a jump in the seismic data processing took place. Within this interval, the analogue magnetic-tape recording and processing, followed by the introduction of digital technique, were introduced. A third and equally important factor that boosted the seismic data processing is the adoption of concepts borrowed from the communication theory which considered the seismic wavelet as a travelling signal similar to the electromagnetic signal. The input data to the processing system consists mainly of the digital seismic traces, recorded by the field recording system. The fundamental principle on which processing is based upon, is that the seismic trace is considered to be as a digital signal of value (amplitude) which is function of the reflection travel time. In order to extract the useful information the seismic signal (seismic reflection wavelet), a number of mathematical and statistical processes, are applied. These processes are considered to be the tools employed to do the required analyses.
9.1
The Seismic Processing Tools
The raw seismic data acquired in the field, which form the input to the processing system, are normally digitally recorded traces on special magnetic tapes. The reflection wavelets received by a surface-positioned detection-system (the geophone group) are digitally recorded as function of recording time forming the seismic trace.
In order to extract the useful message (geological information) from these recorded data, these seismic traces are subjected to a set of analysis procedures, using certain processing tools. These tools are numerical analysis techniques applied on the input seismic traces. The most common tools applied in seismic data processing are: • • • • • • •
Fourier Analysis Correlation functions computations Convolution (frequency filtering) Deconvolution (inverse frequency filtering) Frequency- and velocity filtering Equalization (trace scaling) Sample Editing (time-shifting, sign-changing, sample zeroing)
These processes form the basic processing tools in the hand of the geophysicist, ready to be used in processing of seismic reflection data.
9.1.1
The Sine Function
The building brick of any physically realizable function is the sine function. According to Fourier theorem, a time- or distance-function, is made up of a sum of infinite number of sine-functions. Due to its important role in processing in general, and in Fourier analysis in special, an introductory treatment of the sine function shall be given here-below, preceding the discussions of the processing tools listed above. One way to generate a sine function is by using a geometric approach. Let us consider a unit circle
© Springer International Publishing Switzerland 2017 H.N. Alsadi, Seismic Hydrocarbon Exploration, Advances in Oil and Gas Exploration & Production, DOI 10.1007/978-3-319-40436-3_9
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The Seismic Processing Tools
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Fig. 9.1 Generation of the sine function (sin h)
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