Attenuation of Incoherent Seismic Noise

190 Pages·2020·25.404 MB·English

by  Abdullatif Al-Shuhail, Saleh Al-Dossary

Advances in Oil and Gas Exploration & Production
Abdullatif Al-Shuhail
Saleh Al-Dossary
Attenuation
of Incoherent
Seismic Noise
Advances in Oil and Gas Exploration &
Production
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Abdullatif Al-Shuhail Saleh Al-Dossary
(cid:129)
Attenuation
of Incoherent Seismic
Noise
123
Abdullatif Al-Shuhail SalehAl-Dossary
Geosciences Department Exploration Application
KingFahd University of Petroleum ServicesDepartment
andMinerals SaudiAramco
Dhahran, SaudiArabia Dhahran, SaudiArabia
ISSN 2509-372X ISSN 2509-3738 (electronic)
Advances in Oil andGasExploration & Production
ISBN978-3-030-32947-1 ISBN978-3-030-32948-8 (eBook)
https://doi.org/10.1007/978-3-030-32948-8
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To my grandson Yousef with whom I experienced many types
of coherent and often incoherent lovely noise.
—Abdullatif Al-Shuhail
To my parents, my brothers, my sisters, my wife, my sons,
and my daughters.
—Saleh Al-Dossary
Preface
Seismicdatasuffersfrommanykindsofnoiseresultingfromvarioussources.
Amajorpartofseismicnoiseresultsdirectlyfromtheseismicenergysource
itselfintheformofcoherentnoisesuchasgroundrollandmultiples.Therest
of noise comes from ambientsources (e.g., wind, ocean waves, etc.) as well
asfromtheseismicsourceindirectlysuchasthosegeneratedfromscattering
of seismic waves by random near-surface heterogeneities (e.g., karst). This
bookdealswiththelattertype.Inparticular,thisbookdefinesthesetypesof
incoherent noise and explains in detail how to attenuate them from the
seismic image using various available and new techniques. The level of this
bookismoresuitedforsenior-yearundergraduateandgraduatestudentswho
have gone through a college-level program in science, engineering, or
technology. Having said this, we stress here that this book is self-contained
presenting an extensive introduction to the seismic exploration method.
Chapter1offersabasicintroductiontotheseismicmethodwithemphasis
on petroleum exploration. It starts with a quick overview of seismic waves
andtheirmodificationsbymediumandinterfaceeffects.Thisisfollowedby
a discussion of seismic signal and noise defining various types of coherent
and incoherent noise. The chapter continues to define the different types of
seismicvelocitiesandhowtoestimatethemfromsurfaceandboreholedata.
Seismic energy sources and detectors in marine and land environments as
well as field recording of seismic data are introduced subsequently. This is
followed by a brief account on field procedures to acquire two-dimensional
andthree-dimensionalsurfaceseismicdata.Anexampleofprocessingareal
seismicdatasetfollowsanoutlineofthebasicstepsofaconventionalseismic
data processing workflow. Finally, a quick summary of geological concepts
relevant to the interpretation of seismic data is followed by a review of the
Fourier transform in one and two dimensions.
Chapter2delvesintothetypesofnoisecommonlyencounteredinseismic
images. The non-coherent noise includes the Gaussian or ‘salt-and-pepper’
noise, where noise samples are completely independent. On the other hand,
coherent noise includes jointly Gaussian or ‘filtered’ noise, where noise
samples are correlated. This is followed by a summary of common methods
used to simulate the noise and estimate its parameters. Chapter 3 introduces
classicalnoisefiltersincludingthemeanandmedianfiltersandtheirfastand
vector variations. This chapter also presents a MATLAB implementation of
some of these filters.
vii
viii Preface
Chapter 4 deals with methods of attenuating impulse noise using robust
filters. It starts with an account of impulse noise followed by detailed dis-
cussions of various robust filters and their variations including: the
alpha-trimmed mean and modified median filters. Chapter 5 introduces the
edge-preserving smoothing (EPS) idea and its requirements. It then details
theNagaoEPSalgorithmanditsMATLABimplementation.Itthenpresents
the bilateral filter, which can be considered as a more general form of the
Nagao filter.
Structure-enhanced filters are discussed in Chap. 6. These filters go one
stepfurtherthanEPSbyenhancingedgeswhileattenuatingnoise.Itpresents
the edge-enhancing bilateral filter, which enhances thin structures that are
usually lost in the bilateral EPS filter. The algorithm, its implementation,
general considerations, and its application on seismic and non-seismic ima-
ges are presented next. The chapter continues to introduce the curvature
diffusionfilter,whichsmoothsmainlyalongthedirectionofcurvature.Itfirst
introduces the mean-direction curvature filter, and then, it presents its opti-
mized version which is the minimum curvature diffusion filter. The chapter
concludeswithdetailedimplementationsoftheedge-enhancingbilateraland
diffusion filters.
Chapter 7 presents an extensive account of utilizing signal rather than
noise characteristics. It starts with the Savitzky–Golay filter, which is a
parametric signal model based on a polynomial model for signals. It then
introduces the commonly used nonparametric independent component
analysis (ICA) filter. The chapter gives details on the properties and imple-
mentation of the ICA filter and compares it to its relative principal compo-
nent analysis (PCA) filter.
The last chapter introduces selected advanced denoising filtering tech-
niques. It starts by introducing the structure-guided vector median filter and
its two variants, namely the locally weighted and directionally weighted
filters.Thechapterendsbypresentingtheseismicinterferometryconceptand
details its use in denoising seismic data through the super-virtual seismic
interferometry filter. This filter is illustrated by a MATLAB implementation
and application of it on a real seismic dataset from the Middle East.
WetakethisopportunitytothankKingFahdUniversityofPetroleumand
Minerals for supporting this work under book-writing project number
BW181002.Thisbookwouldhavenotbeenpossiblewithoutthehelpofour
several students and colleagues from KFUPM who helped at various stages
of writing this book. In particular, we thank Eng. Jarvis Cline, Eng. Zaid
Al-Yafeai, and Eng. Maged Al-Shaibani for their help in preparing most of
this book exercises. We also thank Eng. Muhammad Said Abdallah and
Mr. Septriandi Chan for their work in formatting this book chapters and
figures. Thanks also to Dr. Bin Yan from Saudi Aramco for proposing
additional image processing techniques frequently used for noise reduction
and estimation.
Preface ix
Notations
We will stick to the following notation convention.
(cid:129) Boldface letters are used for matrices and vectors. For example, matrix
A and vector a.
(cid:129) Finite length signals are represented by vector or matrix.
(cid:129) Variables are in italic form, and abbreviations are in upright form.
For example, N is the abbreviation of ‘noise,’ while N is a variable
indicating the length of a signal.
(cid:129) Component of a vector or sample of a discrete signal is denoted by its
index with the index included in subscript. For example, the image I is
representedasamatrixanditscomponentsareI½m;n(cid:2),wheremistherow
index, and n is the column index.
(cid:129) If different versions of a signal need to be indicated, we also use a
subscripttodenotethemeaningofthatversionandputtheindexintothe
bracket.Forexample,anoisyversionofacleansignalxisdenotedasx ,
N
and its m—the component is denoted as x [m].
N
(cid:129) Wewon’tmakeadistinctionbetweenrandomquantitiesanddeterministic
quantities (or samples) in notation. They can be distinguished from the
context.
(cid:129) Intensity of image: I½m;n(cid:2).
Dhahran, Saudi Arabia Abdullatif Al-Shuhail
Saleh Al-Dossary
Contents
1 Introduction to Seismic Exploration. .... .... .... ..... .... 1
1.1 Introduction .. ..... .... .... .... .... .... ..... .... 1
1.2 Seismic Waves ..... .... .... .... .... .... ..... .... 1
1.3 Medium Effects on Seismic Waves.. .... .... ..... .... 5
1.4 Interface Effects on Seismic Waves . .... .... ..... .... 6
1.5 Time-Distance (T-X) Curves of Primary Reflections.. .... 7
1.6 Applications of Noise Suppression in Seismic
Exploration... ..... .... .... .... .... .... ..... .... 9
1.6.1 Direct Wave . .... .... .... .... .... ..... .... 10
1.6.2 Head Wave.. .... .... .... .... .... ..... .... 10
1.6.3 Ground Roll . .... .... .... .... .... ..... .... 10
1.6.4 Multiple..... .... .... .... .... .... ..... .... 10
1.6.5 Diffraction... .... .... .... .... .... ..... .... 11
1.7 Seismic Velocities... .... .... .... .... .... ..... .... 11
1.7.1 Model of a Sedimentary Rock.... .... ..... .... 11
1.7.2 Seismic Velocity Types. .... .... .... ..... .... 12
1.7.3 Determination of Seismic Velocities ... ..... .... 15
1.8 Seismic Equipment.. .... .... .... .... .... ..... .... 16
1.8.1 Sources ..... .... .... .... .... .... ..... .... 16
1.8.2 Detectors.... .... .... .... .... .... ..... .... 18
1.8.3 Recording ... .... .... .... .... .... ..... .... 20
1.9 Field Procedures.... .... .... .... .... .... ..... .... 20
1.9.1 2D Seismic Methods... .... .... .... ..... .... 20
1.9.2 3D Seismic Methods... .... .... .... ..... .... 23
1.10 Seismic Data Processing.. .... .... .... .... ..... .... 26
1.11 Seismic Data Interpretation.... .... .... .... ..... .... 28
1.12 Fourier Transform... .... .... .... .... .... ..... .... 28
1.13 Exercices. .... ..... .... .... .... .... .... ..... .... 29
References. .... .... ..... .... .... .... .... .... ..... .... 39
2 Noise in Seismic Image ... .... .... .... .... .... ..... .... 41
2.1 Type of Noise. ..... .... .... .... .... .... ..... .... 41
2.1.1 Non-coherent Noise: Gaussian, Salt
and Pepper .. .... .... .... .... .... ..... .... 41
2.1.2 Coherent Noise: Jointly Gaussian Noise, Filtered
Noise.. ..... .... .... .... .... .... ..... .... 41
xi