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2010 Fall SEG/AAPG Distinguished Lecturer
Abstract: Rumblings from the Laboratory:
Past, Present, and Future
University of Oklahoma, Norman
The complexity of rocks in nature, and its resultant imprint on rock properties, makes empirical laboratory studies necessary and relevant. Numerous efforts are currently trying to use theoretical models to predict petrophysical and seismic rock properties from microscale images of rocks. However, modeling can only honor the physics of the chosen model; measurements are still needed to define and calibrate this physics. Historically, laboratory measurements have been used to develop an understanding of the physical response of rock and fluid systems under various conditions (frequency, temperature, stress, sample size, etc.). Early work was conducted to develop a better understanding of the correlations between compressional velocities, composition, density, porosity, and pore fluid type; this proved crucial to understanding sonic logs and seismic bright spots. The ability to measure shear and polarized shear velocities significantly expanded the applicability of rock physics to geophysical and engineering problems. Combining P and S-wave data, along with concepts of elasticity, provided the basis for lithology and fluid discrimination. Experimental confirmation of the Biot- Gassmann theory provided rock physics with one of the most important tools for the analysis of prestack seismic data.
New directions in rock physics research will extend the application by incorporating petrophysical characterization into our measurement. Concepts of capillarity and wettability are rarely incorporated into seismic modeling; however, both control fluid saturation and distribution. Promising future rock physics research include examination of the effects of pore microstructure on elasticity, examination of velocity behavior at temperatures and pressures equivalent to those found in deep basins, and the effects of CO2 and time on seismic wave propagation through reservoir rocks. Simultaneous measurements of multiple properties will provide stronger modeling constraints. Application of new measurement and imaging technologies will allow us to extract more information from smaller and smaller samples, including samples from drill cuttings.
Our history is rich with examples of how laboratory measurements have lead to innovations in field-scale technologies. This talk will highlight past accomplishments in rock physics, and more importantly, will focus on future directions in rock physics and the promising and critical role of laboratory measurements in the development of new and innovative technologies.