Articles
Central Alberta Aggregate Study
B. Janet Morrissey
An OhmMapper apparent resistivity survey was undertaken at a site in central Alberta to identify and delineate an aggregate deposit. The results show that the apparent resistivity method has defined the lateral and vertical extent of the main aggregate zone as well as several smaller high-resistivity regions on the periphery…
Magnetic and Gravity Methods in Mineral Exploration: the Value of Well-Rounded Geophysical Skills
Henry Lyatsky
The word “geophysics” in oil exploration is often used synonymously with “seismic”, overlooking many other fruitful techniques. In mineral exploration and engineering projects, applicability of seismic imaging is often limited and other geophysical methods take the front seat.
Gravity and magnetic methods, which are discussed in this article, are extremely…
Beyond Isotropy – Part II: Physical Models in LMR Space
Marco Perez
The following is the second part of the article “Beyond Anisotropy – Part 1: A Prestack Perspective” (RECORDER, 35-7). This section provides an in depth analysis of the seismic reflection of anisotropic media, specifically using the Lambda-Mu-Rho (LMR) crossplot. In Part 1, anisotropic reflections were analyzed from the perspective…
A Geoscientist in Antarctica: Following in Shackleton’s footsteps 100 years later…
Susan R. Eaton
I began by assembling the basics for my field trip to Antarctica and South Georgia: surface geology maps, topographic maps, hiking boots, wool socks, a back pack and two digital cameras. My gear list soon ballooned to include a hydrophone, an Iridium satellite phone, a lap top computer, an Arctic-rated…
15 years of passive seismic monitoring at Cold Lake, Alberta
Richard J. Smith
The first test of passive seismic technology at Imperial Oil’s heavy oil operation in Cold Lake, Alberta was conducted in 1995. Since 1998 passive seismic monitoring has been integrated into the commercial operations. There are currently ~100 dedicated monitoring wells with 5, 8, 10 or 12 tri-axial geophones deployed in…
Natural Fractures from the Perspective of Diagenesis
S.E. Laubach, J.E. Olson, P. Eichhubl, S. Fomel, and R.A. Marrett
Information about chemical changes that occur in rocks during burial—diagenesis—can help improve geologic fracture characterization and prediction by accounting for rock mechanical property changes through time and by providing evidence for how fractures grow and become sealed. Diagenesis information can also be a key ingredient in better geophysical interpretation of…
Comparison between faults extracted from seismic and Elastic Dislocation Modelling
Thibaut Cheret, Jonathan Long, and Jonathan Turner
Most fault enhancement techniques rely on enhancing the discontinuities within the seismic signal. However, there is a large variety of phenomena that cause discontinuities in the seismic signal. Furthermore, fault heaves are lower than the Fresnel zone width thus not fully resolvable and as a result, faults are often poorly…
Beyond Isotropy – Part I: A Prestack Perspective
Marco Perez
The seismic response is composed of two parts: the traveltime of a signal from the surface to and from a reflector and the amplitude of the reflection. Of interest here is the amplitude of the reflection, which is primarily a function of material properties at a given geological interface; specifically…
Time Lapse Interpretation of Cold Heavy Oil Production
Ken Hedlin, Arthur Chan and Bob Godfrey
A number of papers have been published that show seismic amplitude anomalies in CHOPS (Cold Heavy Oil Production with Sand) fields correlated with production (e.g. Hedlin & Chan, 2009; Chen et al, 2004 and Mayo, 1996). Modeling and 2D seismic experiments conducted in 2002 by Husky Energy suggested that drainage…
Carbon capture and storage: opportunities and challenges for geophysics
Don Lawton
Carbon capture and storage (CCS) involves capturing CO2 from point-source surface facilities and injecting it into subsurface geological formations, particularly depleted oil and gas reservoirs, unmineable coal seams or deep saline aquifers. In 2008 the government of Alberta committed CDN$2B to accelerate CCS in the province, with the goal of…
Shear-wave sourced 3-D VSP Image Interpretation of Tight Gas Sandstones in Rulison Field, Colorado
Prajnajyoti Mazumdar and Thomas L. Davis
Exploration and development of tight-gas sandstone reservoirs relies heavily on understanding the distribution of sandstone bodies in the subsurface. Shear-wave sourced 3-D vertical seismic profiling (VSP) data are used for sandstone detection and fractured interval delineation. We apply anisotropic Kirchhoff 3-D prestack depth migration to the shear wave VSP reflection…
Isostasy and Gravity Modelling: Integrating Potential Field Data in Interpretation Workflows
David Close
Potential field data, namely gravity and magnetic data, provide a relatively low cost means of mapping regional geological trends and structures. Magnetic data are typically of most value in regions where igneous and metamorphic rocks are common and they have proved particularly vital for understanding the structure and age of…
Shear-wave sourced 3-D VSP Depth Imaging of Tight Gas Sandstones in Rulison Field, Colorado
Prajnajyoti Mazumdar and Thomas L. Davis
Rulison Field, Piceance Basin, Colorado was approved for development drilling to 10-acre spacing in 2003. The down spacing and hydraulic fracturing within this unconventional reservoir has increased its production five fold in less than a decade. A significant portion of the gas production is from low permeability fluvial discontinuous sandstones…
Tight Gas Geophysics: AVO Inversion for Reservoir Characterization
David Close, Simon Stirling, David Cho, and Frederik Horn
A general discussion of some of the critical steps in AVO inversion workflows is included with a Western Canadian case study in this paper. We use the case study to illustrate that the ratio of the compressional and shear wave velocities (Vp/Vs) is a useful indicator of quartz-clay ratios in…
Robust Workflows for Seismic Reservoir Characterisation
Patrick Connolly
In the talk I describe a workflow for seismic reservoir characterisation. The specific problem I address is the estimation of net-to-gross from a clastic reservoir, however the workflow is adaptable for a variety of other applications.
The three main components of the workflow are:
- Extended elastic impedance analysis followed…
A Possible Origin of the Hawaiian Islands
J. Tuzo Wilson
It is noted that different physicists and geologists have in recent years espoused not less than four groups of theories of the physical behavior of the Earth’s interior. Recent observations of submarine geology, heat, and rock magnetism have tended to support some form of continental drift rather than the older…
Model-based Seismic Inversion: Comparing deterministic and probabilistic approaches
Dennis Cooke and John Cant
The target audience of this article is the geoscientist who desires to learn more about seismic inversion and its limitations. The content is especially relevant to those using seismic inversion to help build static reservoir models for field development and/or estimate probabilities for presence of hydrocarbons. The viewpoint and experience…
Logical considerations in applying pattern recognition techniques on seismic data: Precise ruling, realistic solutions
Hosein Hashemi
In this paper, comprehensive method and necessary considerations in seismic pattern recognition procedures are reviewed. In pattern recognition experiments, it is essential to decide about many parameters like picking representative objects with all possible spatial variations, minimum size of training set, knowledge on prior probabilities, seismic attribute redundancy reduction, choice…
Airborne electromagnetic methods: applications to minerals, water and hydrocarbon exploration
Richard Smith
Electromagnetic methods have a transmitter that carries a current that varies in magnitude as a function of time. This current has an associated (primary) magnetic field that has a similar time dependence. According to Faraday’s law of induction, this time varying field induces currents in conductive features in the ground.…
Looking beneath the noise: experience with high-resolution seismic acquisition and pre-stack process
David C. Henley, Malcolm B. Bertram, and Kevin W. Hall
Historically, the design of land seismic surveys has been subject primarily to two influences: the overall dimensions and station spacing of the survey for both sources and receivers has been governed by the depth and configuration of the geological target zone; and suppression of the ever-present source-generated coherent noise has…
