Page 11 - Acquisition and Processing of Marine Seismic Data

2 1. INTRODUCTION

following the digital recording of seismic data in exploration and processing (Flinn et al., 1967).
the mid-1960s, resulting in a considerable Today, seismic data is digitally recorded and
increase in the final seismic image quality after processed before interpretation. Several differ-
proper processing. Thenceforward, the basic ent data-processing steps can be applied to the
goal of the processing has not changed and it is seismic data in different domains, such as
still quite simple: increasing the seismic resolu- time-distance, frequency, frequency-distance,
tion, and enhancement of the signal level while etc. The selection of suitable domain for the
suppressing the noise amplitudes – in other application is dependent on which domain
words, increasing the signal-to-noise (S/N) ratio provides the best separation of signal from
of the seismic data. If the noise embedded in the the noise.
data can be separated by one of its specific char- Seismic data processing consists of several
acteristics, such as its frequency band, propaga- processing steps that are consecutively applied
tion velocity and/or direction, its amplitude to the input data. Such a complete procedure
with respect to the primary reflection ampli- composed of different processing steps is
tudes, etc., then it may be possible to remove termed a processing flow. A basic processing
most of the noise components from the data. flow consists of loading the dataset from disk,
Early noise-suppression applications, when applying one or more processing step(s) sequen-
digital recording and processing techniques tially, and then writing the processed data back
were not available, were accomplished by to the disk (Fig. 1.1). The effectiveness of many
grouping geophones to suppress the coherent processing steps strongly depends on the
noise, such as ground roll in land seismic acqui- parameters used in the previous steps. For ins-
sitions. The technological revolution caused by tance, if a band-pass filter is not properly
World War II also resulted in significant devel- applied before the deconvolution, we will not
opments related to seismic data-processing obtain satisfactory results from the deconvolu-
methodology. The practices used in communi- tion step. Therefore, a processor is responsible
cation technology during wartime were later for proper selection of each data-processing
applied to seismic data by the researchers at parameter and testing of the results of each step
the Massachusetts Institute of Technology in to ensure the quality of the output.
the 1950s, which ultimately advanced the meth- Both for 2D and 3D projects, a whole seismic
odology and approaches utilized in seismic reflection study consists of data acquisition,

FIG. 1.1 Schematical illustration of a typical
Data processing flow
processing flow and the parameters of the
processing steps.
Processing step - 1 Parameter [1]

Processing step - 2 Parameter [1, 2]

Processing step - 3 Parameter [1, 2, 3]

Processing step - 4 Parameter [1, 2]