Page 33 - Acquisition and Processing of Marine Seismic Data

24 1. INTRODUCTION

investment. What makes the seismic reflection • 1976. First multistreamer acquisition.
the most effective geophysical method is that • 1985. First AVO analysis.
the final image obtained by the reflection work • 1989. 4D time-lapse seismic.
is of great detail and spectacular resolution as • 1990. DGPS and acoustic ranging,
compared to the information obtained from widespread 3D seismic acquisition.
any other geophysical technique. Seismic sec- • 1995. First 4C ocean bottom cable (OBC)
tions are quite similar to subsurface geological acquisition in Gulf of Mexico.
cross-sections in appearance. This is also the • 2000. Seismic acquisition with 14 streamers.
most widely used and well-known geophysical • 2003. Development of converted wave-
method, which is mainly because of the exces- processing techniques.
sive investment, especially that made by the • 2005. New technology solid streamers.
hydrocarbon industry on the development of • 2007. Dual-sensor towed streamer.
new acquisition techniques and equipment, as • 2013. Variable depth streamer acquisition.
well as modern and sophisticated processing • 2014. Full azimuth survey.
technology. Due to the continuous investment
2D seismic lines may provide valuable
both for acquisition and processing, new devel-
information about the basins under explora-
opments in the theoretical basis as well as appli-
tion if no other information about the subsur-
cations of the seismic reflection method proceed
face structure and stratigraphy is available.
uninterruptedly over the years.
However, mapping relatively complex struc-
The first applications of the method took
tures and reconstructing the fault pattern of
place in the early 1920s, to discover the possible
thebasin,evenwithadensegridof 2Dseis-
oil reservoirs around the salt domes in Texas
mic lines, may have uncertainties in the inter-
using single-fold or fan-shooting seismic data.
Its theoretical development was based on the pretation stage. Today, 3D seismic is applied
theory of earthquake seismology, since both in the exploration, development, and produc-
methods use elastic waves to understand the tion stages to reduce the uncertainties. In
addition to the precise determination of well
earth’s interior. The milestones in marine seis- locations over the pay zones, 3D seismic pro-
mic reflection exploration can be summarized vides monitoring of the fluid movement in
as follows:
the existing reservoirs as the production
• 1920. John Evans and Bevan Whitney applied continues (which is the basics of time-lapse
for a patent for the reflection method. or 4D seismics).
• 1924. Discovery of oil field beneath the Nash The reduced acquisition time of 3D data
salt dome in Texas. makes marine 3D surveys more economical
• 1932. First analog filters, initiation of seismic and widespread. Onboard QC applications
data processing. and reliable instrumentation ensure high-
• 1937. First seismic survey in Gulf of Mexico. quality 3D seismic data, which has become the
• 1944. Initiation of widespread marine seismic industry standard, especially for the hydrocar-
surveys. bon exploration in the last two decades,
• 1956. CDP acquisition technique. and no drilling is done without a 3D seismic sur-
• 1958. Digital recording and processing. vey in the petroleum industry today, using at
• 1965. Air gun seismic source. least 4 streamers with a minimum length of
• 1971. Streamer depth control. 4–6 km. In processing, 3D depth migration
• 1972. Bright spot technology. has become almost a standard interpretive
• 1976. First 3D seismic acquisition. data-processing method. Today’s limits of the