Leonard James Srnka

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Leonard James Srnka
Latest company Exxon
BSc Engineering Science
MSc Geophysics and Planetary physics
PhD Physics
BSc university Purdue
MSc university University of Newcastle
PhD university University of Newcastle

Leonard James Srnka received a BS in Engineering Science from Purdue University in 1968, graduating summa cum laude. In 1974, he received his PhD in Physics from the University of Newcastle upon Tyne, United Kingdom and from Corpus Christi College, Oxford University, United Kingdom (1970–1973), where he was a Marshall Scholar. Leonard spent his early career working for the NASA Lunar Science Institute as a Postdoctoral Fellow (1974–1976) and as a Staff Scientist (1976–1979) where he researched the origins and evolution of lunar and planetary electromagnetism. The latter part of his career has been spent working at the ExxonMobil Corporation. From 1979–1993 he was project leader and supervisor with assignments in electromagnetic methods, seismic modeling and inversion, and borehole geophysics. He was a supervisor for gravity, magnetics, and remote sensing research and applications (1993–1998). From 1998 to present, Len has been the project leader for land and marine electromagnetic technology, and serves as a member of the senior technical staff. He championed the Remote Reservoir Resistivity Mapping ("R3M") breakthrough research project for upstream applications. He has been the Chief Scientist on numerous marine CSEM surveys offshore Europe and West Africa in 2001–2003. Leonard has special interests in marine MT and CSEM acquisition technology, 3D modeling, data interpretation, and imaging/inversion. He has 26 refereed publications and numerous patents issued and pending. He was awarded SEG's Virgil Kauffman Gold Medal Award for his contribution to the state of the art of hydrocarbon reservoir characterization via remote electromagnetic methods.

Spring 2007 SEG Distinguished Lecturer

Illuminating Reservoirs with Electromagnetics

Marine controlled-source electromagnetics (CSEM) has recently become a significant business tool for upstream applications due to the convergence of many technologies. CSEM provides valuable information on subsurface lithology and fluids independently from seismic data; however, its spatial resolution is much lower. Uptake has been dramatic, with more than 200 industry marine CSEM surveys acquired worldwide since late 2000.

This presentation discusses some results that demonstrate both the promise and the challenges that lie ahead. CSEM can detect and map offshore reservoir hydrocarbon resistivity at depths exceeding 2000 meters. But resistivity determination is hardly a fool-proof method for hydrocarbon identification, since many geologic facies are electrically resistive relative to their surroundings. As marine CSEM matures, it may prove to be the most important geophysical technology for probing below the seafloor since the emergence of 3D reflection seismology 30 years ago. The key determinant of commercial success will be whether the value of CSEM information is worth the money spent, relative to what other data can provide.

Interview with Len Srnka [1]

Leonard Srnka, one of the winners of the 2007 Kauffman Gold Medal, was SEG’s Spring Distinguished Lecturer. He made his presentation “Illuminating Reservoirs with Electromagnetics” at the CSEG convention in Calgary in March and TLE Editorial Board member Satinder Chopra took that opportunity to conduct the following interview:


Tell us about your education and experience.


I received my BS in engineering science from Purdue, a program in which you took fundamentals in many engineering courses and also extra-heavy doses of mathematics and physics as preparation for graduate school. Then I won a Marshall Scholarship, and went to the U.K. and decided to work in geophysics and planetary physics. My major professor was S. Keith Runcorn at the University of Newcastle upon Tyne, who was a Fellow of the Royal Society, an authority in geomagnetism and continental drift, and a principal contact for NASA’s Apollo Program on the British side. I thought that studying with Keith would be a great way to combine geophysics and planetary physics in one place. I needed a bigger lab to do scale-model lunar plasma induction experiments for my thesis, so I moved to the UKAEA Culham Laboratory near Oxford University for three years to make measurements.

How did you develop an interest in electromagnetism?

Partly a result of my engineering degree, and the fact that my dad was an electrical engineer. I worked with him as a summer employee as an undergrad, so I had electrical engineering experience including hands-on work in the middle of the night to fix control systems in steel mills in Cleveland.

Then, in England, Professor Runcorn suggested that I work on whether there is a core in the Moon by electromagnetic sounding methods using data from satellites and some Apollo surface instruments. Geophysical electromagnetism was the focus of my postgraduate work and thesis. I developed strong interests in many geophysical areas while at Newcastle, but electromagnetism has always been of special interest.

Why did you join Exxon?

I was on the staff at the Lunar Science Institute in Houston, and I knew people who had left NASA and had gone to the energy industry. One said: “Exxon is forming a basic research division called Long Range Research and they are looking for nontraditional kinds of oil and gas people—physicists, mathematicians, engineers, etc.—to work on basic geoscience problems. Why don’t you talk to them?” I did and was excited about what I heard and they made me an offer I couldn’t refuse. It has been more than 27 years now for me.

Did you have any particular strategy in mind to carry out with Exxon all this time?

The things that attracted me were the expertise of the staff, very high quality people, and the great variety of assignments that you can have within Exxon, both of which continue to this day. My driving interest since my Newcastle and Oxford days has been understanding the physics of the Earth: What makes the Earth tick, and how does that affect things like hydrocarbon systems? I followed that interest all of my career. I’ve worked in seismology, borehole geophysics, gravity and magnetics, remote sensing, and of course electromagnetics.

For me, all of those areas really are variations of the same theme: How does the Earth work, how can we best understand the way it formed, how it evolved, and what does it look like today. So I really come at it from the scientific point of view of understanding the fundamentals.

What personal and professional visions are you working toward?

I just became a chief research geoscientist for our Upstream Research Company. There are two of us at URC: a geologist and myself, a geophysicist. I expect this assignment will last several years and keep me very busy because I have a very large purview across all geophysical technologies in which our upstream research center works. I am also interfacing with my equivalents in our exploration company. So it is going to be a very busy time for me, and it will probably flash by before I know it.

Tell us something about the different types of work that you have carried out at Exxon.

I was hired by Frank Levin, a senior scientist at Exxon Production Research Company, to work on electromagnetism for hydrocarbon applications. I did this for about six years and then we put this aside for several reasons, partly business and partly technical. I moved into seismology and did very highend physics-based reflection seismology—tomography, prestack inversion, and acoustic and elastic modeling—for a bunch of years. I moved from there into borehole geophysics and became a supervisor, once again looking at seismic and electromagnetic wave propagation, but now cross-borehole and in single boreholes. Then I accepted an assignment with the Technology Department in Exxon Exploration Company, and supervised gravity, magnetics, and remote sensing in the application setting. I had great fun working closely with business units on exploration, development, and production problems all over the world, as well as helping to choose and apply new technology. In 1997, an opportunity arose to champion a breakthrough research project we called Remote Reservoir Resistivity Mapping, so there was a career choice to stay in management or to return to the technical ladder. I chose to go back to the technical side. It’s been a great path for me. I’ve been Houston-based the entire time, had a fantastic career, and hope to have at least five years to go.

What are some of successes that have been achieved?

One, regarding applying electromagnetics to oil and gas, was telling the company all the things it was not good at, which is a very important aspect of anything, making sure you don’t use it in the wrong place. We did develop proprietary electromagnetic techniques which are still at the forefront today for both magnetotellurics and marine-controlled source work. Those were my first patents, now expired, of which I was very proud. I remember telling my dad that I received U.S. and foreign patents. He said that was absolutely thrilling and said, “Now you are a real contributor.” He was very pleased and that was great.

We did a lot of research on marine seismology in trying to determine fluids from marine reflection seismology and published some early papers which appear now in textbooks, so that was a real highlight for me. Somewhat later I did a lot of coordination and planning in the exploration company’s Technology Department, and got to see the whole suite of applications that we do, how those were approved and funded, how they come and go as the business changes externally, and that was another highlight for me. I learned a tremendous amount about the business aspects of being at Exxon. And last, but not least of course, is this project on marine CSEM.

Briefly describe the promise of electromagnetic technology in upstream applications?

I think it has a very bright future. The science is quite sound. I think it will grow as people learn more about what the data mean. How you best integrate these data with other geophysical data sets, for example with seismic reflection, is a key. That’s where you will have the biggest penetration.

There has been a lot of learning. There are 200–250 surveys that have been acquired since late 2000. ExxonMobil has operated something like 20% of those. We continue to take data, and we will probably acquire more surveys in the future in various parts of the world. We are learning how to use marine CSEM in our exploration process, including risking new plays and leads—a very complex process on which we are working very hard in a quantitative sense. I think you will see this technology spread into other parts of the upstream, perhaps first into the development sector, and it will eventually go into the production business where we’ll use it for monitoring. We talked about this at SEG’s 2005 and 2006 annual meetings. People have been studying resistivity logs for a very long time, about 80 years. But we are not used to looking at resistivity in a map or 3D volume sense. Good views of that kind only became possible in the last few years. So we have another learning process to go through, including integration with the rest of our geoscience knowledge. So I think marine CSEM will penetrate many areas. I do not think it’s a magical method to find hydrocarbons. As we say in the United States, it’s not a “silver bullet.” But it is a very valuable geophysical data set.

Not much is said about the land side. Why didn’t electromagnetic technology pick up so fast on land and what can we expect in the future?

The physics isn’t as friendly to the response from horizontal resistive rocks for land EM. That’s the fundamental reason. Onshore CSEM has been around for nearly as long as electrical logging but has never been very effective for deep oil and gas exploration. Onshore use is severely challenged because you are at the surface of the Earth with the air around and above you, so there is a large amount of energy broadcast directly from the source to receivers through the air.


  1. Chopra, S. (2007). ”'Interview with Len Srnka.” The Leading Edge, 26(8), 956–959.

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