Page 10 - Acquisition and Processing of Marine Seismic Data

P. 10

CHAPTER

Introduction

OUTLINE

1.1 Underwater Acoustics 7 1.2.5 Yesterday/Today/Future of Seismic
Exploration at Sea 22
1.2 Marine Acoustic Methods 9
1.2.1 Bathymetric Systems 12 1.3 Fundamentals of Marine Seismics 25
1.2.2 Side-Scan Sonar 14 1.3.1 Seismic Waves 25
1.2.3 Subbottom Profiler 17 1.3.2 Reflection From an Interface 27
1.2.4 Single Channel and Multichannel 1.3.3 Shot Gathers 29
Seismics 19 1.3.4 Reflection Hyperbolas 31

Seismic reflection exploration today is, obvi- intrusions, where subsalt imaging today has
ously, used extensively by the oil and gas indus- become a challenging phenomenon. Continuous
try. Indeed, the increase in new hydrocarbon development of acquisition and processing tech-
discoveries over the last 50 years almost paral- niques of seismic data, after their first introduc-
lels the advancements in data processing and tion in the early 1920s, has resulted in very high-
acquisition techniques. Following the digital resolution subsurface images, which have
recording of seismic data, incorporating the enabled us to discover much smaller hydrocar-
common midpoint (CMP) acquisition technique, bon traps, and it is now possible to map the
powerful workstations are now used to process target levels in much higher detail.
large amounts of digital data using sophisticated Raw seismic data should be processed using
processing applications. This has led to a consid- several complex data-processing steps in order
erable increase in discovery and production to obtain a subsurface image from 2D or 3D
(Fisher, 1991), since these developments have multichannel seismic datasets. This procedure,
provided many quality subsurface images at rel- consisting of a number of sequential mathemat-
atively higher resolution, especially in complex ical processes, is known as seismic data proces-
geological environments such as areas of salt sing. Data-processing applications commenced

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