Articles
New attribute for determination of lithology and brittleness
Ritesh K. Sharma and Satinder Chopra
The discrimination of fluid content and lithology in a reservoir is an important characterization that has a bearing on reservoir development and its management. For the unconventional reservoirs, such as shale gas formations, besides other favorable considerations that are expected of them, it is vital that reservoir zones are brittle.…
Introduction to the Fracture Analysis Focus Articles
Bill Goodway
The paradigm change of hydraulic fracture stimulation is to artificially create reservoirs in unconventional source rocks, where production was previously unimaginable. Effective stimulation requires either the connection to existing natural fractures or the presence of geomechanical brittleness capable of supporting extensive induced fractures. As very few tight formations are thick,…
A Math-free Look at Azimuthal Surface Seismic Techniques
Franck Delbecq, Jon Downton and Mark Letizia
Many interpreters are interested in characterizing fractured reservoirs using 3D surface seismic data, and there are a variety of azimuthal techniques to extract this information from the data. However, once the results from two or more methods are compared the question may arise: why do the results from various azimuthal…
Microseismic, 3D and 4D Applications and its Relation to Geomechanics and Completion Performance
Andrew Iverson, Bill Goodway, Marco Perez and Greg Purdue
This study demonstrates empirical relationships derived from microseismic, 3D inversion attributes and 4D seismic to production in unconventional shale in the Horn River Basin. Production variations are explained through the use of the above mentioned tools and a careful investigation of stimulated rock volume. These production variations are shown to…
4D attenuation analysis for permeability estimates in hydraulically induced fractures
David Cho, Bill Goodway, Marco Perez, Andrew Iverson and Gary F. Margrave
The effect of wave induced fluid motion between fractures and pores results in complex elastic stiffness coefficients that ultimately gives rise to frequency-dependent attenuation. Therefore, permeability estimates are obtainable through a spectral analysis of the seismic wavefield. In this study, we analyze the attenuation response associated with a time-lapse seismic…
CSEG Foundation-sponsored Geophysicist returns to the Bottom of the World…
Susan R. Eaton
was snorkeling in a gin-and-tonic mix of brash ice near a gentoo penguin colony in Antarctica, in February 2010, when a leopard seal charged me, not once but three times, its mouth agape and jaws seemingly detached. Squaring off face-tomask— the leopard seal’s face, my scuba diving mask—I counted the…
An Introduction to Wavefield Visualization: Part 1 Visual Acoustics
Steven Lynch
When writing a paper, convention dictates that you begin with a summary, a concise outline of the subjects that you will cover in more detail in the body of the article. This paper is different because it is itself a summary being little more than an overview to an introduction.…
Introduction to the Processing – Migration / Imaging Focus Articles
Peter Cary
Imaging is always the ultimate aim of seismic processing, and this is usually accomplished primarily by one of the last steps in the processing sequence: migration. This month we have a very interesting and eclectic group of papers devoted to the topics of migration and imaging. Some of these papers…
Complex-beam Migration and Land Depth Imaging
Tianfei Zhu
Gaussian-beam depth migration is a useful alternative to Kirchhoff and wave-equation migrations in imaging geologically complex land areas. It overcomes the limitations of Kirchhoff migration in imaging multipathing arrivals and suffers no dip limits from one-way wave equation approximation. The accuracy of the Gaussian-beam method in solving the wave equation…
Deconvolution After Migration
John C. Bancroft, Thais Guirigay, and Helen Isaac
Deconvolution is a process that is normally applied before migration. However, deconvolution should also be performed after migration to enhance the resolution of the data. This concept has been practiced with some marine processing, but we have met considerable opposition when applying it to land data. We discuss some reasons…
A Review on Least Squares Prestack Migration and its Applications
Naser Yousefzadeh and John C. Bancroft
Kirchhoff least squares prestack migration (LSPSM) attenuates acquisition artifacts resulting from irregularities or sparseness in the wavefield sampling and improves image resolution. This paper provides a brief review on the advantages and disadvantages of using LSPSM. Using synthetic examples, a few applications of LSPSM including improvement in image resolution, the…
Overview on the Fundamentals of Imaging
Brian Schulte
The purpose of this paper is to review imaging, migration algorithms, and velocity model building. It gives an overview on the goals and techniques utilized in imaging of seismic data. The migration algorithms presented are based in the Gulf of Mexico but are applicable throughout the world. It is intended…
Introduction to the Processing – Noise Attenuation Focus Articles
Mauricio D. Sacchi
I am pleased to have observed a renewed interest in seismic signal processing at our latest annual convention. We had an unprecedented number of sessions devoted to seismic signal processing. All of these sessions were well attended, which signals a growing interest in reinvigorating the field of seismic signal processing.…
Rank Reduction of Unfolded Tensors for Pre-stack De-noising and Reconstruction
Nadia Kreimer and Mauricio D. Sacchi
Seismic data can be represented by a N-dimensional tensor that can be unfolded in N matrices. These N unfolded matrices (also called unfoldings) are low rank when the data are composed of a superposition of linear events. Noise and missing observations increase the rank of the unfolded matrices…
Footprint Attenuation with 5D Interpolation
Peter Cary and Mike Perz
In recent years, 5D interpolation has become a very popular method for regularizing seismic data before 3D prestack migration. In addition to its main purpose of reducing the generation of migration artifacts due to irregular spatial sampling, 5D interpolation also has the very beneficial sideeffect of attenuating acquisition footprint during…
Strong Noise – Removal and Replacement on Seismic Data
Patrick Butler
Strong noise on seismic data generally not only obscures the underlying signal but also is spread by subsequent linear processing into other traces. Consequently it is very important to nonlinearly remove it and if we can recover some of the signal underneath. Failing that at least we can use nearby…
White Noise Suppression in the Time Domain
Patrick Butler
White noise forms the basic limit to resolution for seismic data. However we are not usually trying to see a single event on a single trace. We recognise that seismic signal “looks” the same within a time window at least on some adjacent traces. We can use this to nonlinearly…
Preserving sensor vector fidelity using automated multicomponent receiver-azimuth detection
Jeff P. Grossman and Rodney Couzens
P-S converted-wave energy is recorded mainly on the two lateral components of the receiver. Conventional processing of converted-wave energy includes rotation of these laterally polarized data measurements into radial and transverse coordinates. To do this properly, knowledge of the in-situ receiver orientation is essential. However, substantial errors in the recorded…
Introduction to the Microseismic – Applications and Case Studies Focus Articles
Shawn C. Maxwell
Over the last several years, microseismic monitoring has evolved into the primary geophysical imaging method for hydraulic fracturing of unconventional reservoirs. Interest in the technology has also rapidly grown, and we are fortunate that Calgary has become a “hotbed” for technological development. The number and quality of microseismic presentations at…
Microseismic Monitoring of Ball Drops During Hydraulic Fracturing Using Sliding Sleeves
Shawn C. Maxwell and Richard Parker
A relatively new method of completing horizontal wells has recently emerged and is quickly gaining popularity. Unlike conventional well construction using a cemented liner and a series of perforations to create different frac stages along its length, openhole completions using multiple, mechanicallyactivated, sliding-sleeve fracports is increasing commonplace (e.g., Seale and…
