Analysis of velocities, shear wave polarizations and Q factor from VSP data have allowed a better understanding of the near-surface and reservoir at the vicinity of the VSP well. The study on shear wave anisotropy from estimation of shear wave polarization and time delay has enabled the detection of a weak anisotropic zone from the surface down to 1000 ft with a polarization of fast shear waves of N120E. No changes of shear wave polarization angle and time delays have been detected, inferring no variations in the fracture direction, density and local maximum stress over time. However, time-lapse changes in attenuation on each dataset (VSP, 3D VSP and walkaway) are observed at the reservoir after CO2 flooding t he interpretation of the time-lapse borehole seismic data suggests that CO2 has contacted the VSP well along a fracture zone over a time of eight months. Indeed, the structural interpretation enables us to confirm the presence of faults and fracture zones that explain the locations of changes in the fluid properties and CO2 flooding observed from the surface seismic data during the RCP Phases VI and VII.

Gwenola Michaud earned a M.S. in Geophysics at Strasbourg, in 1997 and a B.S. in Mathematics and Computer Sciences at Pau, in 1994. Before beginning her Ph.D. program at Mines, she worked at the Compagnie Generale de Geophysique (CGG) at Massy. Her studies at the CSM were sponsored by CGG.

Luca Duranti has a B.Sc. in Geology from the University of Florence, Italy (1990). He worked for Schlumberger from 1991 to 1996, enjoying the international assignments and the diversity of projects he was involved with. In September 1996 he started graduate work with the Reservoir Characterization Project at the Colorado School of Mines.

In the geophysical world, time-lapse seismic technology has been rapidly advancing over the past few years. Several industry case studies are presented that show 4D seismic is able to monitor injected fluid fronts, locate bypassed oil, map pressure compartmentalization, and delineate the sealing or leaking flow properties of faults. High-resolution time-lapse seismic monitoring has been performed in the borehole, in VSP and crosswell geometries. Together, time-lapse surface and borehole seismic techniques have the possibility to cover multiple reservoir scales in terms of both spatial and time-lapse resolution. Permanent installation of receiver arrays, originally motivated by increased repeatability and signal-to-noise energy, have the potential to offer useful benefits in data acquisition cost reduction and real-time surveying flexibility. Since multi-component receivers can be installed for nearly the same price as acoustic sensors, the additional information from shear waves can be useful for monitoring pressure fronts, in situ stress, and real-time fracturing. However, many hardware, software, deployment and logistical issues remain to be solved before permanent seismic arrays become a practical reality.

David E. Lumley is co-founder of 4th Wave Imaging Corp., a seismic imaging R&D company offering expert solutions and services in 4D time-lapse seismic reservoir monitoring and multi-component seismic data analysis. His previous work experience includes a position as a Senior Staff Research Scientist with Chevron Petroleum Technology, and research and operations assignments with Arco Research, Mobil R&D Corp., and Mobil Canada. Prior to that, David worked as a seismic crew leader for Western Geophysical on marine seismic vessels in the Gulf of Mexico and the North Atlantic. David received a B.Sc. and M.Sc. from the University of British Columbia, and a Ph.D. from Stanford University where he now visits as a Consulting Professor. David currently serves on the SEG Research Committee, is Chair of the 2001 SEG Summer Research Workshop, and is a member of the AGU, SIAM, SEG and SPE. David has received several awards for his papers and presentations, and is a recipient of the 1996 SEG Karcher Award for research scientists.

In the second part of my talk, I will examine AR and ARMA models in the context of f-x random noise attenuation. I will show that an ARMA model provides the proper representation for a superposition of plane waves immersed in white noise. Finally, I will discuss the relation that exists between the ARMA representation, the Pisarenko harmonic estimator and the projection filtering techniqueproposed by Soubaras (SEG 1994, 1995).

Mauricio D. Sacchi was born in Colonel Brandsen, Argentina. He received his Diploma in Geophysics from the Department of Astronomy and Geophysics, National University of La Plata, Argentina, in 1988 and a Ph.D. in geophysics from the University of British Columbia, Canada, in 1996. He joined the Department of Physics at the University of Alberta in 1997 as an assistant professor of Geophysics. His research interests are in seismic data processing, imaging, time series analysis and inverse theory.

This presentation will focus on practical aspects of naturally fractured reservoirs. Key points will be illustrated with data from reservoirs in Argentina, Colombia, USA, Canada and Australia. The first example highlights how a drastic gas production decline due to water encroachment in a field producing from a naturally fractured reservoir was stopped by producing more water from flank wells that had already watered-out completely. The second case shows the importance of long periods of swabbing. A key to proper evaluation of a fractured formation is to swab at least the amount of mud lost during drilling operations. Not doing so might lead to the abandonment of a reservoir that otherwise could be commercial. Underbalance drilling helps to solve this problem in many naturally fractured reservoirs. The third case demonstrates how poor assumptions regarding porosity, permeability, and water saturation cut-offs might lead to the improper testing and perforating of a well. The fourth case present's problems associated with not intersecting natural fractures. In these cases, a conventional test might yield negative results, even if the matrix blocks are hydrocarbon saturated. The fifth example highlights poor well testing designs that are typically associated with very short flow and build-up periods. The sixth example discusses poor completions. They are the result of not drilling the wells thinking in terms of natural fractures.

Roberto Aguilera, Ph.D., is president of Servipetrol Ltd. in Calgary, Canada. He has an undergraduate degree in petroleum engineering from the Universidad de America in Bogota, Colombia, and a master's and doctorate in petroleum engineering from the Colorado School of Mines. As a consultant since 1978, he has conducted petroleum-engineering studies and has presented his short course on Naturally Fractured Reservoirs throughout the world.

Dr. Aguilera has developed various techniques for evaluation of naturally fractured reservoirs that have been published in leading journals of the oil industry. He has authored and was a contributor to various books including Naturally Fractured Reservoirs (PennWell, 1980 and 1995).

Reservoir Characterization Project Phase VII acquired a time-lapse multicomponent 3D seismic survey in Vacuum Field, New Mexico, for CO2 injection monitoring and permeability, fluid and flow characterization.

Multicomponent AVO analysis is a powerful tool for porosity and permeability estimation. Plane-wave reflection coefficients are inverted for density, fracture density and shear velocity contrasts, using a weighted least squares technique. The interpretation of the AVO attributes estimates porosity and permeability of the reservoir. Some examples from Vacuum Field will be discussed, comparing the estimates obtained with data derived from other sources, like well-log derived porosity, production statistics and CO2 injection results. AVO attributes estimates, along with time-lapse analysis, applied to CO2 injection monitoring and orientation can increase Vacuum Field recovery ratio by 15%.

Luis H. Amaral is an MS candidate in the Department of Geophysics at Colorado School of Mines, working in RCP Phase VII. He earned his BA in geology for Universidade de Sao Paulo, Brazil, in 1982. He joined Petrobras in 1983, which sponsors him, and worked in seismic data acquisition and processing. He spent 8 years in Amazon; most of them involved in operations in the jungle. When he left Brazil for CSM, he was manager of geophysics for Sergipe-Alagoas basin, in the northeast of Brazil.

Keith Hirsche started his geophysical career in 1977 as a line crew helper. Since 1982, he has worked in geophysical research and development for GSI, Western and Hampson-Russell Software. During this time, his primary research interests have included VSP, multi-component seismology and the use of seismic data in reservoir characterization and monitoring. Keith is currently employed at Hampson-Russell Software where he is consulting on reservoir-related projects and supervising software development for time-lapse seismic monitoring applications.

Palpation is routinely used for the evaluation of mechanical properties of tissue in regions that are accessible to touch. This means of detecting pathology using the "stiffness" of the tissue is more than 2000 years old. Even today it is common for surgeons to feel lesions during surgery that have been missed by advanced imaging methods. Palpation is subjective and limited to individual experience and to the accessibility of the tissue region to touch. It appears that a means of noninvasively imaging elastic modulus (the ratio of applied stress to strain) may be useful to distinguish tissues and pathologic processes based on mechanical properties such as elastic modulus. To this end many approaches have been developed over the years. The approaches have been to use conventional imaging methods to measure the mechanical response of tissue to mechanical stress. Static, quasi-static or cyclic stresses have been applied. The resulting strains have been measured using ultrasound or MRI and the related elastic modulus has been computed from viscoelastic models of tissue mechanics. Recently we have developed a new ultrasound technique that produces speckle free images related to both tissue stiffness and reflectivity. This method, termed "Ultrasound Stimulated Vibroacoustography" (Science 280:82-85, April 3, 1998; Proc Natl. Acad. SCI USA 96:6603-6608, June 1999), uses ultrasound radiation pressure to produce sound vibrations from a small region of the tissue that depend on the elastic characteristics of the tissue. The method can detect microcalcification within breasts, and promises to provide high quality images of calcification within the arteries. In addition, vibro-acoustography can detect mechanical defects in certain prostheses such as artificial mitral and aortic valves. The method may also be used in nondestructive evaluation, and for underwater communication.

James F. Greenleaf was born in Salt Lake City, UT, on February 10, 1942. He received the BS degree in Electrical Engineering from the University of Utah, Salt Lake City, in 1964, the MS degree in Engineering Science from Purdue University, Lafayette, IN, in 1968, and the Ph.D. degree in Engineering Science from the Mayo Graduate School of Medicine, Rochester, MN, and Purdue University in 1970. He is currently Professor of Biophysics and Associate Professor of Medicine, Mayo Medical School, and Consultant, Department of Physiology, Biophysics, and Cardiovascular Disease and Medicine, Mayo Foundation. He has served on the IEEE Technical Committee for the Ultrasonics Symposium for five years. He served on the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society (UFFC-S) Subcommittee on Ultrasonics in Medicine. Doctor Greenleaf was President of the UFFC-S in 1992 and 1993 and is currently Vice President for Ultrasonics. Doctor Greenleaf has ten patents and is recipient of the 1986 J. Holmes Pioneer Award and the 1998 William J. Fry Memorial Lecture Award from the American Institute of Ultrasound in Medicine and is a Fellow of IEEE, American Institute of Ultrasound in Medicine, and American Institute for Medical and Biological Engineering. Doctor Greenleaf was the Distinguished Lecturer for IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society (1990/1991). His special field of interest is ultrasonic biomedical science, and he has published more than 291 articles and edited or authored five books in the field.

Last summer, the Colorado Avalanche Information Center (CAIC) provided financial support to fund undergraduate research in avalanche forecasting. Two students in the Department of Geophysics analyzed weather and avalanche-occurrence data from Berthoud Pass spanning the twenty-four year period from 1970 to 1994 and implemented a nearest-neighbor algorithm to aid avalanche forecasters this season.Three other undergraduates continued the research program during fall semester, extending the nearest neighbor algorithm and doing a preliminary analysis of data from Red Mountain Pass.

This presentation consists of two parts. The first part will include a brief overview of avalanche forecasting and a review of work done at Mines in collaboration with the CAIC. The second part will feature aspects of the Swiss avalanche-forecasting program, which is generally recognized as the most advanced in the world.

Terry Young is Professor and Head of the Department of Geophysics at Colorado School of Mines. Prior to coming to Mines last January, Terry spent eighteen years in the petroleum industry where he managed geophysics research for Mobil Corporation and led an exploration team in the U.K. sector of the North Sea. Terry earned his B.A. from Stanford University, and his M.S. and Ph.D. from Colorado School of Mines.

Alexandre Gret is a Ph.D. candidate in the Department of Geophysics at Colorado School of Mines. Alex earned his M.S. at ETH Zurich. During his military service, Alex participated in the Swiss avalanche-forecasting effort by making observations in the field and transmitting data back to a central site for processing and analysis.

Steve Pride received his B.A. in geophysics from the University of California at Berkeley (1985) and his Ph.D. from Texas A&M (1991). After a post-doc at the Earth Resources Laboratory at MIT (1991-1993) he accepted a tenured academic post (called ``maitre de conferences'') at the Institut de Physique du Globe de Paris where he taught from 1993-1997. Since 1997 he has been a professor of geophysics at the University of Rennes in France where he lives with his wife and two young children. He is currently a visiting professor at Stanford University through to August of 2001. His research interests are in all aspects of rock and crustal physics. Recent projects include such diverse subject areas as two-phase flow in porous media, crack localization during brittle fracture, theory of poroelasticity, electrokinetic phenomena in the crust, and the electrical conductivity of shaly sandstones.