Page 121 - Acquisition and Processing of Marine Seismic Data

112 2. MARINE SEISMIC DATA ACQUISITION

FIG. 2.67 A comparison of (A) conventional and (B) P-cable seismic data. Data Courtesy of TGS.
A high S/N ratio can be achieved by increas-
2.5 DATA ACQUISITION
PARAMETERS ing the signal level while trying to reduce the
noise amplitudes. A proper determination of
source and receiver geometry may reduce the
The suitable selection of data acquisition
source-generated noise amplitudes as well as
parameters both in 2D and 3D seismics widely spatial aliasing. A good temporal resolution is
affects the quality of the collected data. The achieved by recording seismic data with a wide
determination process of acquisition parameters frequency bandwidth, which involves both low-
is termed seismic survey design, the main pur- and high-frequency components at the same
pose of which is to optimize the survey to obtain time to resolve the upper and lower boundaries
the most suitable seismic data that matches the of the target. The bandwidth of the data at its
requirements of the survey. In practice, these higher frequency end is limited by the source
parameters are determined in conjunction with and receiver ghost notches, and different acqui-
the requirements of the survey, and in general
sition geometries are introduced to eliminate
they are selected to produce a suitable source
the negative effect of, especially, receiver ghosts
signal and to record the best quality data with
to improve the seismic signal bandwidth
a minimal noise component, providing that they
(Section 2.2.3). A good data coverage requires
suit the cost and HSE (health, safety, and envi-
a suitable definition of inline and crossline
ronment) requirements for the entire survey.
receiver spacing to avoid spatial aliasing.
Good seismic data can be defined by its three
A successful seismic survey design provides
specific characteristics (Ashton et al., 1994):
for obtaining the goals of the conducted seismic
• High S/N ratio survey in a cost-effective manner, within the pre-
• Good temporal and spatial resolution determined time schedule of the survey. In the
• Good spatial coverage for 3D selection of suitable survey parameters, the