Articles

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April 1997

Multivariate Geostatistics

Brian Russell and Dan Hampson

Multivariate geostatistics is a broad term that encompasses all geostatistical methods that utilize more than one variable to predict some physical property of the earth. Bivariate geostatistics is obviously the simplest subset of the multivariate techniques and thus the standard technique of cokriging could be called multivariate geostatistics. However, in…

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March 1997

Whither Seismic Imaging?

Samuel Gray

Seismic imaging has evolved to the point where, with sufficient knowledge of the propagation velocities, we can now obtain accurate images, before stack in three dimensions, of almost arbitrarily complicated geologic structures, and we can do this at reasonable cost. That is not to say that we can close the…

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March 1997

Registration (Licensure) of Geoscientists in Canada: A National Perspective and Update

Gordon D. Williams

The registration (licensure) of professionals such as doctors, lawyers, engineers and, increasingly, geoscientists in Canada is the responsibility of individual provinces and territories, under acts of their respective legislatures. These acts limit or restrict the practice of the professions to those persons who are registered (licensed) by autonomous, self-governing professional…

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February 1997

Rock Physics and 4D Seismic for Improved Oil Recovery

Dr. Amos Nur

The worldwide volume of already discovered but unrecovered oil is by now enormous – on the order of (according to some) the oil that still remains to be discovered. On average, only 25% of discovered oil is being recovered in the world, whereas 65% to 75% is considered recoverable. Consequently,…

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February 1997

Geostatistical Depth Mapping: Integration of Seismic Times with Well Tops

David L. Garner

A perpetual exploration problem is to produce depth maps useful for the goals of both geologists and geophysicists and to accurately derive a target depth estimate at a proposed well location. A case history whereby seismic horizon times and well tops are combined to estimate depth using the collocated co-kriging…

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January 1997

Using Technology for E&P Success – the Practices of the Leaders

George Eynon

The western Canadian petroleum exploration and production industry has evolved considerably since the oil price shock of 1986 and the gas price shock of 1990-92. Early adjustments focused on reducing G&A. The second, current phase has an operating emphasis. The primary goal is to meet shareholder objectives - whether those…

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January 1997

Migration Operator Aliasing and its Effect on Interpolation

Peter Cary and Bill Goodway

The controversial topic of 3D spatial sampling and its impact on the final seismic image has generated several articles in the last few years advocating coarsely sampled acquisition geometries (e.g. Neidell, 1994; Goodway & Ragan, 1996). On the other hand, Vermeer (1995) has advocated a fine, "symmetric" sampling geometry in…

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December 1996

Pre-stack Inversion: Evolving the Science ofInversion

Rick Wallace and Roger Young

Over the past 2 decades seismic inversion, ostensibly the process of deriving rock properties from seismic measurements, has evolved significantly. The early methods of recursive inversion converted seismic traces to well log traces providing a measurement of the "pseudo acoustic impedance". The acoustic impedance could also be expressed as "pseudo-acoustic…

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December 1996

One Interpreter’s Most Excellent Adventure

Jan Dewar

Synthetic seismograms are a common tool in geophysical interpretation. They make use of the simple idea of correlating known subsurface information from a well with seismic data recorded on the surface. But sometimes a synthetic seismogram does not match a seismic section very well, and what should be a straight…

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December 1996

Geostatistical Reservoir Characterization of A Canadian Reef Or The Use and Abuse of Geostatistics

Keith Hirsche, Larry Mewhort, Jan Porter-Hjrsche and Rick Davis

Geostatistical methods are becoming widely accepted in reservoir characterization. The appeal of these techniques is the ability to integrate diverse types of information, including seismic data, into a consistent subsurface model. An added benefit of geostatistics over deterministic reservoir description is the ability to assess uncertainty in the modelling process.…

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November 1996

3D Seismic Monitoring for Enhancing Thermal Recovery

John Eastwood, Don Anderson and Tom Boone

A technique is illustrated which uses a single 3D seismic monitor survey along with multiple seismic attributes in conjunction with an offset baseline survey to discriminate heated reservoir from unheated reservoir. 3D seismic monitoring has definitively mapped steam heated regions of the reservoir at two separate geographic locations encompassing more…

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November 1996

In the Foothills, Prestack Depth Migration IS Interpretive Processing

Samuel H. Gray and Gary Maclean

In the Foothills of the Canadian Rocky Mountains, explorationists face a wide spectrum of challenges, ranging from economic ("Is my prospect large enough to justify a multi-million dollar well?" "Can hydrocarbons be transported from the well to the market inexpensively?") to technical ("Can I map my structure using seismic data?"…

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October 1996

Surface Seismic Data Acquisition: Current Technology, Trends and Issues

Dr. Fred J. Barr

We currently find ourselves armed with a dazzling array of technologies with which to acquire seismic data. These technologies, as well as their attendant trends and issues, have developed in response to both market and technical forces, powerful forces at work for several decades. The market forces demand lower costs…

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October 1996

Cascaded Dipole Filters: Extending the Limits of Seismic Resolution

Penny B. Colton and Atul Nautiyal

In the challenging world of mapping thin stratigraphic targets, a geophysicist may choose to try a tactic for increasing resolution, particularly if it is simple, quick and has a known effect. The dipole filters described below, with either even or odd iterations (zero or 90 degree phase shift), can be…

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September 1996

Mining Exploration: A New Frontier for the Canadian Seismic Industry

David W. Eaton, Bernd Milkereit, Matthew Salisbury, Erick Adam and Jianjun Wu

Like the oil and gas industry, the mining industry is a cornerstone of the Canadian economy, with production of non-fuel minerals in the order of $12 billion annually. With a few notable exceptions (e.g., the spectacular Voisey Bay nickel-cobalt discovery in Labrador), the Canadian mining industry is looking progressively deeper…

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September 1996

Surprises in Glauconitic Incised Valley Channel Exploration Using 3D Seismic: Risks and Opportunities

Marilyn J. Mawdsley, Alma L. Eamer and Brian A. Zaitlin

Exploration risks commonly associated with the seismic definition of Lower Cretaceous incised valley channel sandstone (IVCS) reservoirs are: I) the distinction of shale versus sandstone and 2) ambiguities caused by seismic interference from both the underlying Paleozoic unconformity and younger Mannville coals. A post-drill review of two wells drilled during…

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June 1996

The Integration of Logs, Borehole and Surface Seismic

Dick Ireson

The calibration or AVO Walkaway technique, where the downhole geophone array is placed just above the reservoir, is gaining acceptance as a tool for evaluating the full elastic response of the reservoir local to well locations. It may also be used to evaluate the velocity anisotropy of the layers in…

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June 1996

The Blackfoot Seismic Experiments: Broad-Band, 3C-3D, and) 3-D VSP Surveys

Robert Stewart, Robert Ferguson, Susan Miller, Eric Gallant and Gary Margrave

A number of paths could lead to fundamental advances in seismic exploration. These include: broadening of the recorded frequency band, use of the full 3-D elastic properties of the Earth, and 3-D borehole images. We would like to extend the recorded seismic frequency band (both up and down) to increase…

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June 1996

Geoscientist Registration in Ontario

As of March 10, 1996, the Association of Geoscientists of Ontario was formed, following from the Committee for Professional Registration of Geoscientists in Ontario. The aim of this organization is to promote establishment of a system for geoscientist registration in Ontario and to provide a formal channel for communication with…

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June 1996

The Evolution of Shallow Marine Data Acquisition in Canada

Peter Kitson

Prior to 1984, shallow marine exploration in Canada was almost non-existent. Most recording systems were not readily adaptable for working on water. There were no marine cables. Airguns had been in Canada for some time, but were used primarily for infill coverage and testing. Some equipment had been brought in…