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Houston Geological Society Bulletin

Abstract


The Houston Geological Society Bulletin
Vol. 61 (2018), No. 3. (November), Page 16

Abstract: R.E. Sheriff Lecture: Navigating Messy Rock Physics Problems

Gary Mavko1

Two common tools for modeling physical properties of rocks are Estimators and Bounds. Estimators predict a particular value of rock property: for example, Archie's Law to predict saturation or porosity, or Gassmann's equations to predict how effective moduli change when the pore fluid changes. In contrast, bounds predict the range of possible rock properties, given the limited information that we typically have in geophysics. Rock microstructure and heterogeneity are critical - determining where the measured value falls within the bounds, and why predictors sometimes fail or mislead us.

In this presentation, I'll show strategies for using bounds to navigate messy rock physics problems. Examples include (1) using bounds to test and sometimes falsifying popular predictors, (2) using bounds to infer microstructure from common measurements, and (3) using bounds, themselves, as predictors, especially in complex materials such as unconventionals. I'll also touch on a less familiar topic: using bounds on the cross-relations between different measurements (elastic modulus, electrical resistivity, dielectric constant, thermal conductivity, etc.) on the same rock. Cross bounds help us to validate our multi-physics measurements and our assumptions used to interpret measurements.

Biographical Sketch

Gary Mavko is a Professor of geophysics at Stanford University. He received his PhD in geophysics from Stanford in 1977. Gary then joined the Tectonophysics branch of the USGS in Menlo Park where he worked in areas of rock physics and earthquake fault mechanics. In 1984 Gary joined Entropic Geophysical, in its first months as a start-up reflection seismic processing company. Gary developed many of Entropic's algorithms and software for reflection and refraction analysis, and eventually became their VP of research and development. He returned to Stanford in February, 1989, and is now Professor (Research) of Geophysics. He has been working on modeling and analysis of the acoustic properties of rocks and techniques of seismic interpretation for rock and fluid properties. In 2001 he was elected an Honorary Member of the Society of Exploration Geophysicists "for his deep understanding of rock physics and for the distillation of his ideas into the "squirt" theory for porous, saturated rocks". Gary was a 2006 Distinguished Lecturer of the Society of Exploration Geophysicists.

Acknowledgments and Associated Footnotes

1 Gary Mavko: Professor Emeritus, Stanford University

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