Peter Gretener is an Emeritus Professor at the University of Calgary. He joined the University in 1966, the year it received its charter as an independent institution. On the occasion of the university’s 40th anniversary, Satinder Chopra and Helen Isaac met Peter to hear his views on universities, the oil industry, what geophysics is all about, and life in general.
Peter, to start, why don’t you tell us about your educational background?
In 1949 I obtained an M.Sc. in petrology from the Federal Institute of Technology in Zürich, because I was born in Switzerland you know, and in 1953 I got a Ph.D. in geophysics, gravity actually, from the same Institution. I give my professors, Paul Niggli and the famous Fritz Gassmann, full credit for a thorough exposure to the fundamentals, which to this day serves me well. I chose gravity because we had just obtained a brand-new Worden gravimeter. Seismic instruments were home made in those days and our electronics expert was more interested in designing sound systems than seismic amplifiers. As a result we had already two people on the waiting list and I was not about to be number three.
How did you decide to come to Canada?
In a country essentially devoid of any natural resources a geophysicist/geologist is like the Big Eye Swiss cheese, an export article, and where does a European go and not become a permanent expatriate? North America, Australia and New Zealand are about the only choices, at least I never heard of anybody getting landed immigrant status in, say, China. The USA demanded either a sponsor or $5000, which was SFr.20,000 or, in plain English, a hell of a lot of money. I had neither and so I ended up in Canada. Remember, in 1953 globalisation was still a very limited concept. Geophysics was a new science and one had to launch into lengthy explanations when one professed to belong to this profession. All I knew was that the University of Toronto had a geophysics department so I applied for a Post Doctoral Fellowship, which was also a new concept in those days. Tuzo Wilson was the Department Head, a big man with this great big booming voice and an unquenchable enthusiasm for his science. This was in his pre-plate days and to mention Wegener’s name was not advisable. Ironically, as you know, he later became a major contributor to plate tectonics with his elucidation of the transform faults. Tuzo also asked numerous times “Where are the Canadian diamonds?”. Well, fifty years later they were found and today Canada ranks among the major diamond producers, as described by my friend and colleague, the late Al Levinson. Tuzo’s unabashed and infectious enthusiasm as an earth scientist was a refreshing experience after the stiff-upper-lip approach of his European colleagues that I was used to. In my times Tuzo was just busy populating all the geophysics departments springing up everywhere. Garland had just left for the UofA in Edmonton and Russell, Farquharson and Cummings were still there.
You worked with King Hubbert at Shell from 1962-66. Tell us about Hubbert’s famous predictions and your impression about them.
I worked for Shell from 1954 to 1966; the last four years down in Houston at the Shell Lab. In those years I lived through the glorious days of fieldwork as a geologist. For example, in 1957 I mapped the flat areas between the Great Slave and Great Bear lakes east of the Franklin Mountains. Now, how could a Gassmann student end up in such a position? My first mentor, fondly remembered I might say, was Arne Junger, a wild Dane with the looks of an Einstein and a new idea every day. When he told management that knowledge was an exploration tool this didn’t go over too well. He was naturally in what was the technical specialist stream. Arne was known as the “crazy” guy who ran records to more than ten seconds down in Montana, sort of an early Lithoprobe. In these more leisurely days the upstream end in the oil patch was taken for granted by higher management - a fact that only occurred to me much later when reading “The Prize” by Yergin in the 90’s. With Arne I studied the differential compaction around reefs and it was he who released me to the geology section to do some fieldwork and get it out of my system. Now a geophysicer with a degree in geology is highly suspect and had to be relegated to an area where he could do little damage. I had five field camps that year and soon found out that you can’t move a 4x8 plywood sheet with a Beaver. We had to rent an Otter from Ward Air in Yellowknife, a small bush outfit at the time.
At the Shell Lab I ran into King Hubbert and John Handin and his group of geomechanics people. This is where I got interested in geomechanics, an orphan of geophysics. In my opinion King Hubbert is one of the outstanding contributors to our geological knowledge in the 20th century. His sandbox, which lets you create normal and thrust faults in sand, is nothing short of a stroke of genius. Let me also say that this is only the tip of the iceberg. We could easily run an early geology/geophysics course with numerous demonstrations, such as the physicists do worldwide. I introduced the tilted oil/water interface, another Hubbert demonstration, and also the lava lamp for the mechanism of diapirism, the evacuated sand filled balloon for bearing strength of loose soils and the concept of turbidite sedimentation. In western universities committed to research, rather than teaching, these attempts meet with little favour and often outright resentment. To return to Hubbert let me say that to this day Hubbert & Willis 1957 on hydraulic fracturing is a definitive treatise of this topic and Hubbert & Rubey 1959 on thrust faulting and geopressures remains a classic. His predictions about the duration of the “oil age” made the front page of the National Post in September of 2005.
You pursued this interest in Geomechanics here at the UofC didn’t you?
My initial mandate at the UofC was to acquaint geology graduates with geophysics. That was in 1966. I figured that enough people were getting involved in processing seismic information and turned to geomechanics, a field recognized only in a few North American universities, while Tom Davis began the formation of a geophysics division in the geology department and after his departure Don Lawton continued the job and never looked back.
Tom Davis went to CSM and you were there from 1993-2003. Tell us about that experience.
Sorry, there is a misunderstanding here. I retired from the UofC in 1992 and was the Keck Visiting Professor at CSM in 1993/94. Generally a North American state or provincial university trains piano players, medical doctors, engineers and philosophers united in a faculty of graduate studies that maintains a common standard between these disciplines. This, on closer examination, is ludicrous. CSM has a limited mandate – resource exploration and exploitation and, more lately, environmental rehabilitation, often made necessary by the former. This limited goal is far more manageable.
After your education in Zürich you worked at oil companies and universities. Which stint did you like the most and why?
For my professional development there is no doubt that the Houston experience was most essential. However, living in the Gulf Coast was not my cup of tea and when leaving I looked for a job in God’s country, which for me lies between Tucson and Edmonton. Returning to Calgary in 1966 I had a decision to make: hang out my shingle or crawl into the Ivory Tower. I opted for the latter for the following reason. A freelancer not only has to be a respected professional but needs to have some business acumen and people must feel comfortable around him. My business sense leaves much to be desired and I am not “one of the boys” - I come on too strong. Also in academia one justifiably can contemplate life as a geologist dealing in millions of years. No regrets.
Looking back at your geophysical career, could you share with us some of your memorable stories?
Teaching the engineers one day a Chinese student pushed the office door open a bit wider, stuck in his head and said “Dr. Gretener, I heard bad things about your course but I have changed my mind”. Before I could react he was gone. Makes your day.
One day on the shores of Great Bear Lake, Jim Murphy the heli pilot said: “Our tail rotor bearing is loose. If it goes, we go round and round.” Well we snuck along the beaches and made it back to camp where we were AOG till the parts arrived. That was in 1957 when travelling to Inuvik was a daylong affair.
What do you think is your most important contribution to geophysics? Or what career accomplishments are you most proud of?
Some 40 years ago the CSPG, in conjunction with the UofA extension, ran the “Banff Conference”, just about the best thing that ever happened in continuing education. It was conceived and laid out by Gordon Williams, to give credit where it belongs. After almost 20 years as chairman Gordon got tired and I took over for five years. The conference lived for another two years, chaired by Jack Century and Fred Trollope, and eventually died. Anyway we tried.
In terms of papers, I wrote on the subject of the rare event in geology. Events of low possibility are classified as impossible on the human time scale yet figure as certainties on the geological time scale. This also brings about the fact that many changes occur as a series of jumps rather than a continuous change. For the change as such it makes no difference, but for the understanding of the process at work the distinction may be all important. Turbidite sedimentation and fault movements are typical examples of such ephemeral processes.
I read with interest your article on “The Gassmann Story” published in the Leading Edge in August 2002. Close to the end of that article you say “In times when we no longer have geophysicists or seismologists, but migrators, inverters, AVO analysts, acquisitioners, anisotropists, interpreters, etc. we need the intradisciplinary in addition to the interdisciplinary dialog.” While I follow your advice there, I wanted to ask you about some of these terms that you use, migrators, inverters, acquisitioners…is there an element of sarcasm that you planted in there? Surely, it is the call of the day to have people with such expertise. Are you disappointed at this? What would you like done here?
I have no difficulties with people specializing. All I say is from time to time look across the fence. Your question indicates that besides interdisciplinary communication we now also need intradisciplinary dialogue. A good piece of news: as of this fall the Geology and Geophysics Department at the UofC offers a graduate degree in reservoir characterization in conjunction with the Department of Chemical and Petroleum Engineering. This closing of ranks between engineers, geologists and geophysicists is to be applauded.
Let’s touch upon the Poisson’s ratio debate. In spite of your and Leon’s request that PR doesn’t enter seismological equations in a natural way and so we should leave it for the mechanists for whom it was designed, the term continues to be used unabated in the AVO literature and other places. I would like your comments on this.
No real damage done since only Vp/Vs is used. However, they are not enhancing their reputation as physicists.
In your expert opinion, which are the directions where R&D efforts should be directed?
A large number of geophysicists will work in reservoir characterization. Let us take a closer look. As Roy Lindseth said in 1989 “...a seismic signal has no intrinsic value except as a carrier of geologic information...”. Just what is that information? The nuts and bolts of the reservoir fluid flow are: PERMEABILITY, POROSITY, HETEROGENEITY, ANISOTROPY, in that order. An investigation into the Archie equations shows that Hubbert was wrong when he stated that Ohm’s law and Darcy’s law are mathematically AND physically equivalent. Electrical and hydrodynamic flow are not physically equal, electrical being a function of porosity only, hydrodynamic flow responding to pore geometry as well. Thus the only way to get permeability values is by direct measurements such as plug tests, minipermeameter tests or bulk tests such as draw down or pressure pulsing. Heterogeneity means that individual tests on small volumes are greatly diminished in value. Under such conditions a large number of lower accuracy tests, such as minipermeameter tests, are preferable over a few cumbersome high precision tests. What can seismic contribute? In a fragmented reservoir 4-D seismic can identify compartments that were swept and drawn down to the bubble point. In his 1976 milestone paper Norm Domenico has shown that the P-wave velocity collapses with just a few percent of free gas. In his case the moral of the story was: a seismic gas sand is not necessarily a commercial gas sand. Naturally 3-D seismic can always identify porosity. The relationship between porosity and permeability is weak and tenuous and may be non- existent. Yet it is all we have. For the engineers the best well to reservoir connection is achieved by the branched horizontal well. In order for such a well to be a good producer the well must have a large section of high near-well permeability. It should also access as many hydraulic compartments as possible. Reservoir characterization is used to design the horizontal well. Much R&D work will be done along these lines. Old and small fields are a liability for the majors but may be a bonanza for a small company. Under new management they will yet yield substantial amounts of additional oil.
WCSB is maturing. Do you think there is enough potential here in Alberta to let us remain employed and for all these new graduates to get jobs?
In view of the previous conclusion I would say that there is much life left in the WCSB.
In your role as Professor Emeritus, do you get a chance to mentor students? You have an invaluable wealth of experience.
No. We live not only in the oil and gas age but also in the age of instant coffee, instant soup and instant wisdom.
What is your perception about writing? Is it sharing of information, experience, knowledge or something else? Have you been doing this?
I have followed my own advice and have been very wide ranging. During teaching you return to your ideas once a year. Unless you lay out your thoughts in a systematic way you will have a difficult time to recover your previous approach. Thus I published much for my own benefit.
What do you enjoy most about teaching?
You have to bring things down to the simplest level and there is always a better, shorter and more effective way of doing it. Also frequently you discover that a concept you have been teaching for a long time has yet another and possibly much more important ramification.
Do you have an example of that?
I can give you examples where a certain concept has seen very different applications. Whether one or the other is more important depends on the composition of the audience.
- What I call the “Domenico Effect” originally explains why certain geophysical gas sands are non-commercial. Now this same phenomenon lets us see reservoir compartments drawn down past the bubble point by applying 4-D seismic.
- Well break outs can be located with the one-arm caliper log and formations likely to be troublesome in drilling can be identified. The 4-arm caliper log shows that the not-to-gauge hole section is distinctly elliptical. This allows us to take things a step further and to draw conclusions in terms of the orientation and magnitude of the virgin rock stresses, which is important for the artificial fracing process.
- The “packing of spheres” is a good approximation of a well sorted and well rounded clastic sediment. Depending on compaction the porosity varies from 26 to 48 percent. In terms of the Archie equations it means that for a given compactive effort the porosity will be 30% and the tortuosity will be equal regardless of the grain size for both electrical and hydrodynamic flow. However, hydrodynamic flow will be proportional to grain size squared. Thus for two packings differing only in grain size by a factor of 5, porosity will be equal but permeability will differ by 25 times, suggesting that no real relationship exists between porosity and permeability. So any conclusions regarding permeability on the basis of porosity are highly tenuous at best. Yet, in terms of porosity, we cannot compact such a material to a porosity of less than 26%, provided there is no crushing of the material. Anybody walking a sand or scree slope of this type knows how awkward and tiresome this is. This aspect of limited compactability has found an application in the new truck run-away lanes. The old lanes lead in a terrifying slope straight to heaven. The new ones gently catch the trucks in a bed of loose gravel. Example? Yes on highway 93 coming down to Castle Mountain Junction. Has it been put to the test? You bet, just look for the evidence.
- The sonic log. Initially it was meant to give us a very detailed account of the velocity distribution, which it does of course, but its main importance is now that of a porosity tool.
You have witnessed many advances in terms of geophysical technology, computerization, information technology. How do you feel when you look back over the last 40 years? Do you like the fast communication with email, internet, or complicated algorithms being run on fast computers?
I envy the present generation as far as digital photography is concerned. No more “lost” slides now that you can carry thousands of them in your hip pocket. However there is a tendency in modern presentations to overwhelm the audiences by throwing everything and the kitchen sink at them in rapid succession. It does not help to improve the “transmission” when the “receiver” is constrained.
What other interests do you pursue?
I still hike as far as my legs will carry me. In the winter I do a lot of reading. For general information I find The Economist most valuable and for the oil patch the Oil and Gas Journal is very good. Right now there are some interesting discussions going on. Simmons, in his “Twilight in the Desert”, maintains that the Saudis have to use all of the modern technology to maintain their production of 10 million barrels per day and will not be able to meet the foreseeable increase in demand. The IEA, on the other hand, sees the Saudis producing up to 18 million barrels per day and producing 15 million barrels per day past 2030. Thus it will either be business as usual for the next 15 years or we will have to cope with shortages in the very near future. It is highly disturbing that credible sources should arrive at such vastly different results. By the way for the US to replace their 20 Mb/d would require about 1000 major power plants each with a 1000 MW installed capacity, either nuclear or coal fired. Since this is electricity it would also necessitate a complete rebuilding of the infra-structure.
What advice would you give the young geophysicists entering our profession?
Keep your professional training broad. Do not treat the university as a trade school. There are meaningful social and humanities courses to be taken. One wholesome experience is “ Technology of Ancient Times”. Absolutely amazing what we were able to do some say 2 or 3000 years ago. It provides a different perspective of our own time. However, in order to make such things possible the technical schools must choose their humanistic counterparts carefully. Many still harbour a Luddite mentality. Thus at CSM the humanists were located in the centre of the campus at Stratton Hall. For them this was a beleaguered bunker in enemy territory. An invitation to debate the two cultures of C. P. Snow was politely declined as being “old hat”. More modern humanists will accept the technical skills of Homo sapiens as an integral part of being human and take a more tolerant view of the technocrats.
I thought you said earlier that it is ludicrous to have piano players and scientists in the same grad school?
In my opinion the whole question of the graduate faculty requires rethinking. Where I come from graduate students are an integral part of their departments and respective faculty. Particularly in the broadly based state and provincial universities of North America the separation of graduate students into a special graduate faculty is not beneficial for the learning experience of the student body as a whole. One should not forget that for the freshman the big heroes are the just finishing doctorands and not the professors. It is those who have just handed in their theses; those that have successfully walked the path one is about to embark on. So I have nothing against the piano players, just don’t put them in a graduate faculty with scientists.
Thank you very much Peter for giving us this opportunity to hear your views.
Well, I hope I have been a little bit controversial to get your readers thinking.