Chapter 17
Seismic Exploration
Nazmul Haque Mondol
17.1 Introduction
Of all the geophysical exploration methods, seismic
surveying is unequivocally the most important, primarily because it is capable of detecting large-scale to
small-scale subsurface features. Simply stated, seismic
methods involve estimation of the shapes and physical
properties of Earth’s subsurface layers from the returns
of sound waves that are propagated through the Earth.
Early wildcatters found oil by drilling natural oil seeps
and large folds (anticlines) in exposed rocks. These
easy oil prospects were all quickly discovered and
drilled, and geologists then turned to seismic surveys
to find less obvious oil and gas traps. Seismic technology had been used since the early 1900s to measure
water depths and detect icebergs, and by 1924, seismic
data were first used in the discovery of a Texan oil field
(Milligan 2004). Several introductory and advanced
textbooks (e.g., Telford et al. 1990, Sheriff and Geldart
1995, Yilmaz 2001) describe the principles of acquisition, processing and interpretation of seismic data. This
chapter reviews the fundamental concepts employed in
seismic exploration.
In general, two types of seismic method (reflection
and refraction) are common, with reflection seismic the
most widely used technique in hydrocarbon exploration. This technique provides an image of the subsurface in two or three dimensions (2D or 3D) (Fig. 17.1).
The subsurface seismic images are produced by
generating, recording and analysing sound waves that
travel through the Earth (such waves are also called
seismic waves). The density and velocity changes
between rocks reflect the waves back to the surface,
and how quickly and strongly the waves are reflected
back indicates what lies below. Seismic pulses for
exploration surveys are generated in one of three
ways, employing an air-gun, vibrator or dynamite. An
air-gun source is used for marine acquisition whereas
vibrator and dynamite are the common sources for land
seismic surveys. The strength of pulses associated with
different seismic surveys varies, depending on sitespecific factors such as rock types, how deep the survey
needs to image and the required source.
17.2 Basic Principles
The first step in seismic exploration is to acquire data,
which in most cases is carried out from the surface. To
understand the seismic data, a review of the physical
principles that govern the movement of seismic waves
through layered media is necessary. A seismic source
at any point on the Earth generates four types of
seismic waves: compressional (P-wave), shear (Swave), Rayleigh (ground roll) and Love, that travel
through the layers (Fig. 17.2). Each layer will have a
specific density and velocity. Rayleigh and Love
waves are surface waves and propagate approximately
parallel to the Earth’s surface. Although surface waves
penetrate to significant depth in the Earth, these types
of waves do not propagate directly through the Earth’s
interior and have limited significance in oil and gas
exploration. On the other hand, P- and S-waves are
often called body waves because they propagate
N.H. Mondol (*)
Department of Geosciences, University of Oslo; Norwegian
Geotechnical Institute (NGI), Oslo, Norway
e-mail: nazmul.haque@geo.uio.no
K. Bjørlykke (ed.), Petroleum Geoscience: From Sedimentary Environments to Rock Physics,
DOI 10.1007/978-3-642-34132-8_17, # Springer-Verlag Berlin Heidelberg 2015
427
Seismic Exploration
Nazmul Haque Mondol
17.1 Introduction
Of all the geophysical exploration methods, seismic
surveying is unequivocally the most important, primarily because it is capable of detecting large-scale to
small-scale subsurface features. Simply stated, seismic
methods involve estimation of the shapes and physical
properties of Earth’s subsurface layers from the returns
of sound waves that are propagated through the Earth.
Early wildcatters found oil by drilling natural oil seeps
and large folds (anticlines) in exposed rocks. These
easy oil prospects were all quickly discovered and
drilled, and geologists then turned to seismic surveys
to find less obvious oil and gas traps. Seismic technology had been used since the early 1900s to measure
water depths and detect icebergs, and by 1924, seismic
data were first used in the discovery of a Texan oil field
(Milligan 2004). Several introductory and advanced
textbooks (e.g., Telford et al. 1990, Sheriff and Geldart
1995, Yilmaz 2001) describe the principles of acquisition, processing and interpretation of seismic data. This
chapter reviews the fundamental concepts employed in
seismic exploration.
In general, two types of seismic method (reflection
and refraction) are common, with reflection seismic the
most widely used technique in hydrocarbon exploration. This technique provides an image of the subsurface in two or three dimensions (2D or 3D) (Fig. 17.1).
The subsurface seismic images are produced by
generating, recording and analysing sound waves that
travel through the Earth (such waves are also called
seismic waves). The density and velocity changes
between rocks reflect the waves back to the surface,
and how quickly and strongly the waves are reflected
back indicates what lies below. Seismic pulses for
exploration surveys are generated in one of three
ways, employing an air-gun, vibrator or dynamite. An
air-gun source is used for marine acquisition whereas
vibrator and dynamite are the common sources for land
seismic surveys. The strength of pulses associated with
different seismic surveys varies, depending on sitespecific factors such as rock types, how deep the survey
needs to image and the required source.
17.2 Basic Principles
The first step in seismic exploration is to acquire data,
which in most cases is carried out from the surface. To
understand the seismic data, a review of the physical
principles that govern the movement of seismic waves
through layered media is necessary. A seismic source
at any point on the Earth generates four types of
seismic waves: compressional (P-wave), shear (Swave), Rayleigh (ground roll) and Love, that travel
through the layers (Fig. 17.2). Each layer will have a
specific density and velocity. Rayleigh and Love
waves are surface waves and propagate approximately
parallel to the Earth’s surface. Although surface waves
penetrate to significant depth in the Earth, these types
of waves do not propagate directly through the Earth’s
interior and have limited significance in oil and gas
exploration. On the other hand, P- and S-waves are
often called body waves because they propagate
N.H. Mondol (*)
Department of Geosciences, University of Oslo; Norwegian
Geotechnical Institute (NGI), Oslo, Norway
e-mail: nazmul.haque@geo.uio.no
K. Bjørlykke (ed.), Petroleum Geoscience: From Sedimentary Environments to Rock Physics,
DOI 10.1007/978-3-642-34132-8_17, # Springer-Verlag Berlin Heidelberg 2015
427