SEG Honorary Lecturer Europe 2009

Rick Miller

Per Avseth

(Geophysical Adviser Odin Petroleum AS, Bergen, Norway, Adjunct Professor, NTNU, Trondheim, Norway)

"Mind the gap in seismic reservoir prediction: How rock physics can bridge the gap between qualitative geology and quantitative geophysics"

Abstract

The field of rock physics represents the link between qualitative geologic parameters and quantitative geophysical measurements. Increasingly over the last decade, rock physics stands out as a key technology in petroleum geophysics, as it has become an integral part of quantitative seismic interpretation. Ultimately, the application of rock physics tools can reduce exploration risk and improve reservoir forecasting in the petroleum industry.

Traditionally, rock physics has focused on the understanding of how seismic signatures change as a function of hydrocarbon saturation, porosity, and pressure; with great breakthroughs made in laboratory experiments and theoretical modeling. Today, rock physics has extended its turf and plays an important role in the basin scale characterization of the subsurface, being an integral part of both well log and seismic data analysis. This lecture shows the importance and benefit of linking rock physics to geologic processes, including depositional and compactional trends. It further documents that lithology substitution can be as equally important as fluid substitution during seismic reservoir prediction. It is important in exploration and appraisal to extrapolate away from existing wells, taking into account how the depositional environment changes as well as burial depth trends. In this way rock physics can better constrain the geophysical inversion and classification problem in underexplored marginal fields, surrounding satellite areas, or in new frontiers.

The presentation includes practical examples and a North Sea case study to demonstrate a best-practice workflow, together with limitations and pitfalls, where rock physics models are combined with well log and prestack seismic data, sedimentologic information, inputs from basin modeling, and statistical techniques to predict reservoir geology and fluids from seismic amplitudes.

Content: Society of Exploration Geophysicists

Biography

Per Avsethis a geophysical adviser at Odin Petroleum in Bergen, Norway, and a consultant to oil companies within the field of quantitative seismic interpretation and rock physics analysis. He is also an adjunct professor in applied geophysics at Norwegian University of Science and Technology (NTNU) in Trondheim, Norway. Per received his M.Sc. in Applied Petroleum Geosciences from NTNU in 1993, and his Ph.D. in geophysics from Stanford University, California, in 2000. His career includes one year at Norsk Hydro Exploration in Oslo, Norway, as seismic interpreter, and five years at Norsk Hydro Research Centre in Bergen as a research geophysicist. He has extensive worldwide experience in applying quantitative seismic interpretation methodologies in North and South America, Africa, and Europe. Per Avseth is the coauthor of the book Quantitative Seismic Interpretation – Applying Rock Physics Tools to Reduce Interpretation Risk (Cambridge University Press, 2005).

Content: Society of Exploration Geophysicists

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