For Fractures, P + S = Maximum Efficiency   
By Bob Hardage / August 2011

In areas where fracture-producing stress fields have been oriented at different azimuths over geologic time, there can be fracture sets of varying intensities and different orientations across a stratigraphic interval.

Measuring Fractures – Quality and Quantity   
By Bob Hardage / July 2011

As has been emphasized in the three preceding articles of this series, when a shear (S) wave propagates through a rock unit that has aligned vertical fractures, it splits into two S waves – a fast-S (S1) mode and a slow-S (S2) mode.

S-Waves on Crack? Not So Much   
By Bob Hardage / June 2011

This month we continue our series on S waves and factures by taking a look at another laboratory measurement that illustrates an important behavior of S waves that propagate in fractured media.

Turn, Turn, Turn: Rotating for S-Wave Data   
/ May 2011

This month we expand our insights into the behavior of seismic S waves as they propagate through a fractured interval, with the emphasis placed on laboratory data of real S waves propagating through fractured real-Earth media.

S Waves Prove Their Worth With Fractures   
By Bob Hardage / April 2011

When a shear (S) wave propagates through a rock unit that has vertical fractures oriented at a reasonably consistent azimuth, it splits into two S waves that propagate with distinct velocities.

Getting More From Frequency-Enhanced Data   
By Bob Hardage / March 2011

Seismic attributes are particularly effective for extracting subtle geologic features from relatively noise-free seismic data. However, seismic data are usually contaminated by both random and coherent noise, even when the data have been migrated reasonably well and are multiple-free.

Riding the Waves: Getting S- When Getting P-   
By Bob Hardage / February 2011

For decades, seismic analysis of subsurface geology has been limited to information that can be extracted from compressional-wave (P-wave) seismic data – but numerous geophysicists are now becoming aware of the advantages of combining shear-wave (S-wave) data with P-wave data.

A Whole Lotta Shakin’ Going On   
By Bob Hardage / January 2011

Seismic contractors are continually searching for methods that will expedite seismic data acquisition – which is why several efforts have been made over the past three decades to develop procedures that will allow vibrators to shake simultaneously at different source stations, with the data being recorded by a common receiver grid.

Last Call: The Even-Integer Rule  
By Bob Hardage / December 2010

The final guideline that should be used when designing a 3-D survey is the use of the even-integer rule for specifying the exact dimensions of a recording swath.

Next Step: Is Stacking Fold Acceptable?  
By Bob Hardage / November 2010
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Geophysical Corner

Geophysical Corner - Satinder Chopra
Satinder Chopra, chief geophysicist (reservoir), at Arcis Seismic Solutions, Calgary, Canada, began serving as the editor of the Geophysical Corner column in 2012.

The Geophysical Corner is a regular column in the EXPLORER that features geophysical case studies, techniques and application to the petroleum industry.


Geophysical Corner

Geophysical Corner - Bob Hardage
Bob A. Hardage, senior research scientist at the Bureau of Economic Geology, the University of Texas at Austin served as editor of the Geophysical Corner from 2006 to 2011.

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