Unconventional Seismic Imaging of Unconventional Reservoirs – Direct Fracture Imaging using Holography
Dr. Norman S. Neidell
In 1997, N. S. Neidell authored a series of papers in Geophysics, The Leading Edge, demonstrating that seismic data from standard surveys could be imaged to substantially greater resolution by using Holography in place of Signal Analysis. Examples of the technique were offered in which a Point Diffractor Model of the subsurface was used as the Holographic Imaging vehicle. Subsequent papers by Enders Robinson and Elmer Eisner, in this same publication confirmed the validity and viability of this approach, and offered also some important commentary and insights.
Experience with this Imaging method quickly showed that many of our ideas concerning the nature of the subsurface were not correct or always useful. It was established early on that the highest attainable resolution did relate to the approximations of the imaging surfaces in representing the physical circumstance, the accuracy and precision of the velocity information, signal/noise conditions, but even more so on the geological nature of the boundary. A true specular boundary for example could show frequency content in the hundreds of Hertz. More typical boundaries such as wave-action Carbonates or High-energy Sand deposition (Turbidites for example), were bounded by more modest frequency limits owing to variations of properties over the effective Fresnel zones giving rise to the Reflections, and also vertical grading or transitioning of the lithology. Still, high frequency limits obtained by Holographic Seismic Imaging were 3 to 5 times greater than those which could be obtained by standard methods.
Recent work imaging only Diffractions within Seismic Data have clearly demonstrated that vertical fractures within reservoirs can be imaged. Papers by Landa, Hilterman, and Popovici, all concur in this conclusion. These Diffractions would of course be correctly treated by the Holographic method as employed by Neidell. To see them as images however we would need to provide sufficiently fine enough spatial and time sampling (perhaps 0.1 msec and 1 ft.). This is a simple enough matter to arrange. The sampling in the domain of reflection wavefield capture, and in the Image domain are quite independent. We just need to assure as Eisner advised that there are more information samples of the wavefield than we require of the subsurface image.
An intriguing application is now suggested. A surface arrangement of detectors could record a survey with numerous source positions (using an appropriate source). A fracture pattern might then be imaged within a reservoir formation as well as other variations within that formation. Such information has potential information content suggesting where wells might best be drilled, and once drilled subjected to hydraulic fracturing. Repeating the survey several hours or more after the fracking would show the new fracture pattern. These would relate to production conduits which would be of importance to the ultimate production.
Norman s. Neidell received a B.S. Degree from New York University, a Post Graduate Diploma in applied Geophysics from Imperial College and a Ph. D. in Geodesy and Geophysics from Cambridge University. He acquired basic experience with Gulf Oil and Seiscom-Delta, and then undertook independent ventures and consulting in 1971. His special interests include seismic stratigraphy, reservoir definition, and imaging technology resulting in international recognition for his work. He has extensive experience consulting and lecturing in all aspects involving seismic data and wavefield imaging. Clients served include most of the major oil companies and significant independents, national oil companies as well as numerous small operators and large landowners. He has authored numerous technical papers and patents and made presentations before many learned group both in the U.S. and abroad.
Dr. Neidell co-founded GeoQuest International (now part of Petroleum Information) and GeoQuest Systems (now a Schlumberger Company) and Zenith Exploration co. serving as its President and Chief Executive Officer. He co-founded Gandalf Explorers Intl. Ltd., which by merger became MMS Petroleum, PLC which explored for oil and gas and operated licenses in four Eastern European countries. He served as a Director and Technical Advisor to MMS Petroleum PLC, a public company in Ireland and the U.K. until its acquisition in December 1998 by Ramco Energy. He was with Zydeco Energy as Vice President of Technology. In July 1999, Dr. Neidell reinitiated his consulting practice, which is currently ongoing. In 2011 he cofounded Starboard Energy. One of his current interests includes applications for the new ultra-high resolution method of holographic seismic imaging which he has developed.
He was Adjunct professor in the Geology Department of the University of Houston. Dr. Neidell is a Past President and Honorary Member of the Geophysical Society of Houston (GSH), a Distinguished Lecturer for the SEG and an Honorary Life Member, a Past Associate Editor of Geophysics and a member of several AAPG and SEG committees. He lectures in Continuing Education Programs for the AAPG, SEG and SPE as well as for several universities. He is a Registered Professional Geophysicist (California) and Professional Geoscientist (Texas) and a Certified Geologist (Arkansas and SIPES).