Mind the gap in seismic reservoir prediction: How rock physics can bridge the gap
Honorary Lecturer 2009 - Europe

SBS

Per Avseth
Geophysical Adviser Odin Petroleum AS, Bergen, Norway
Adjunct Professor, NTNU, Trondheim, Norway

Summary

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.

Biography

Per Avseth

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).

Like a rolling stone

Per Avseth, SEG’s First Europe Honorary Lecturer

Swish! The spring and summer of 2009 just flew by—like a rolling stone down a steep slope! After visiting more than 20 venues all over Europe during my SEG Honorary Lecture tour, I am back to “normal” life again. It is now time to flatten out and recollect the memories of all the great meetings: the discussions with 100s of geopeers; the culinary dinners; the gregarious students and joyful social gatherings; the tasty beers in Leeds; the peaty whiskeys in Aberdeen; a sharpening shot of vodka in Novosibirsk; and many more “cheers, prosts, saludes and nastrovjes.” Add to that the exciting guided tours and world-class sightseeing of historical places, buildings, and monuments.

My lecture tour in Europe has been very intense, yet professionally fruitful and socially intriguing. From the kick-off in Leeds in February to the final trip abroad to Tel Aviv in June, and terminating it all with a last lecture at Statoil in Stavanger in September, I have had the privilege to speak to more than 1200 people. I was very happy to see such great interest in the application of rock physics in seismic reservoir prediction. I was also very pleased that the audience spanned a wide range of different backgrounds, including petrophysicists, reservoir engineers, mining geophysicists, seismologists, hydrologists, seismic processing geophysicists, sedimentologists, and environmental geophysicists. Their input, questions, and feedback often made me learn more than I taught them. The value of new perspectives, and talking to people outside my field of interest, I found very valuable. I feel I have returned from the tour with a boost in my own creativity. I also hope I have given some of the auditing students and professionals some inspiring new ideas.

My tour also served as a great cultural and historical experience: from the Roman wall in Leicester to the Roman aqueducts in Israel; from the mythical Red Square in Moscow to the notorious Peoples Palace in Bucharest, astonished by the golden domed cathedrals and churches of Kiev and thrilled by an entertaining ballet performance in Novosibirsk; refreshed by a run at dawn in Hyde Park; and equally content by a run at dusk in the subtropical mountains near Barcelona. I walked in the footsteps of Socrates upon Acropolis in Athens, biked around in the hidden streets of Tel Aviv, and strolled around in historical neighborhoods of Leiden. I enjoyed swimming in the Mediterranean Sea; had a picnic on the levees of the Jordan River, and tasted excellent seafood at a beachfront restaurant in Patras. I eventually asked myself: Why the heck do I live in an arctic country?

Finally, it was a pleasure and a great honor to represent SEG as an honorary lecturer and an ambassador, to meet with fellow members and to encourage students and geoscientists all over Europe to become members, if they had not yet joined. SEG plays an important role in creating venues for collaboration, boosting creativity and technological innovation, and binding together networks of geophysicists all over the world. In a time when energy security, clean water supply, and CO2 capture are at the forefront of global challenges, I do not doubt that many people I was fortunate to meet during my tour will play a signifi cant role in ensuring that the world will encounter these challenges in a sustainable way. The vital role of geophysicists and other geoscientists in the society will not decline in the near future—even if we run out of oil. We will last for long, just like rolling stones!

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