POINT OF VIEW: More growth seen in use of geophysical methods

Sept. 24, 2007
The use of geophysical methods has spread from the fringes of exploration to the heart of reservoir management during a quarter-century of technological expansion that the incoming president of the Society of Exploration Geophysicists expects to continue.

The use of geophysical methods has spread from the fringes of exploration to the heart of reservoir management during a quarter-century of technological expansion that the incoming president of the Society of Exploration Geophysicists expects to continue.

Fred Aminzadeh, president and chief executive officer of dGB-USA, Sugar Land, Tex., sees potential for seismic and other geophysical applications in areas from which they’re now absent.

One such area is reserves certification. Aminzadeh wants SEG to be included in the reserves committee comprising the Society of Petroleum Engineers, Society of Petroleum Evaluation Engineers, and American Association of Petroleum Geologists.

And he thinks the US Securities and Exchange Commission, which audits reserves disclosures by publicly traded oil and gas producers, should apply geophysical methods in its studies, incorporate geophysical advances of the last 30 years in regulations and requirements for reserves disclosures, adopt “resource” disclosure criteria, and add a geophysicist to a staff now dominated by engineers.

“Most of the reserves certification laws or parameters or guidelines were written 20 or 30 years ago, when there was no 3D or 4D seismic, when there was no three-component, four-component, or any of the advanced techniques that have come up,” Aminzadeh says.

In an interview, the new SEG chief made clear that the evolution of geophysical technology guides his thinking on a range of subjects, including integration of oil-field operations and data, interdisciplinary training, and communicating-to the oil and gas industry and beyond-what his profession can do.

“It is our responsibility to make sure that we convey the correct image regarding what we do, what type of thing we offer, what type of major impact that we can make and are making, whether it is reducing finding costs, or whether it is reducing production costs or placement of wells,” he says.

Modern methods

In the assessment of reserves and resources, Aminzadeh says, modern geophysical methods reduce uncertainty about the four main risk factors: structure, reservoir, seal, and charge.

Three-dimensional seismic techniques, for example, greatly improve the precision and accuracy of interpretations of reservoir structure, including depth, shape, and lateral extent, Aminzadeh notes.

And interpretation based on amplitude variation with offset (AVO) and other seismic attributes has become an effective way to address reservoir risk. AVO makes use of differences in the reflection signal strength that occur as distances vary between shot and receiver points (offsets). Analysis of those changes can yield reservoir information such as lithology and fluid content.

Aminzadeh says gas-chimney technology, combined with techniques for accurately mapping faults, can help assess the other main risk elements: seal and charge.

Gas-chimney technology identifies migration of natural gas through subsurface strata, either vertically or along faults.

“All of these advances have made it possible for geophysicists to help get a better handle on those parameters that eventually go into reservoir risking and reserve calculation,” Aminzadeh points out.

Geophysical techniques also can help establish new criteria for “resource certification,” he adds. The criteria would encompass properties that can be proven to show a “reasonable chance” for discovery of hydrocarbons that can be developed into proved reserves.

“If you want to have a correct valuation of the company,” he says, “you should be able to have some number that financial communities can put their hands on and see that the company does not have any production but has some resources.”

Dynamic characterization

In the field, seismic applications have advanced beyond the static analysis of reservoirs to what Aminzadeh calls “dynamic reservoir characterization.”

Four-dimensional (sequential 3D) surveys can show “not only what the reservoir looks like and what its properties are right now but how it is evolving through time,” he explains.

The value of 4D seismic acquisition and interpretation points toward “the instrumented oil field,” in which companies leave seismic geophones or hydrophones in place for multiple surveys.

While the technology has been applied in a few, mostly offshore fields, the instrumented oil field “is not as common as you would like it to be,” Aminzadeh says. “In today’s economic structure you need to have a really large field to make economic sense.”

As computer technology lowers costs, however, instrumentation will increasingly become part of field design. This will increase the use of other techniques that remain for now in a category Aminzadeh calls “boutique activity.”

One seismic method likely to benefit in this manner is multicomponent (vector wave field) acquisition and processing. Another is elastic wave inversion, a method of deriving subsurface density and as well as compressional and shear velocity profiles from seismic data.

“With all the advances in seismic technology, still we need complementary geophysical data to better evaluate our fields,” Aminzadeh says. “Such recent success stories include controlled-source electromagnetic and borehole gravity data.”

Integrating disciplines

Additional complementary data come from operations other than geophysical work and from professionals other than geophysicists.

This fusion of various data types requires the intelligent integration of disciplines, according to the new SEG chief.

“Geophysicists by themselves can’t do the job,” he says. “Geologists by themselves can’t do the job, geochemists, well log analysts, petroleum engineers....”

In a 1996 article in the Journal of Petroleum Science and Engineering, Aminzadeh proposed that the disciplines of geoscientists and engineers be integrated, rather than simple data integration, in the manner that their work was being integrated in the early stages of exploration and production.

“We will be forced to bring down the walls we have built around classical disciplines such as petroleum engineering, geology, geophysics, and geochemistry or at the very least make them more permeable,” he wrote.

More than 10 years on, some of those walls remain.

“In order to make this integration work, you need to have a group of people that have some reasonable knowledge of other disciplines,” Aminzadeh says. Achievement of that aim requires adaptation of the educational system. Medical schools provide a model.

“They train generalists before they go to a specialty,” he says. “We probably should take a page from their book and try to train for some more general-purpose type work for industry professionals, which I call ‘geo-engineer.’ This has already started happening.”

Aminzadeh relates integration of disciplines and interdisciplinary education to his appeal for refinement of the image that geophysics projects to other oil and gas professionals, regulators, and a public needing energy.

“The best way to get the image right is to train people,” he says. And training about energy-and the technology and people that produce it-should start early.

“If we are serious about energy independence and making sure that we have energy for future generations then we need to have investment in education from very early on, including from high school.”

Future methods

Aminzadeh sees geophysical methods advancing on a number of fronts-some pushing them further into operations in which they haven’t been used much, if at all, before.

The acquisition of seismic data during drilling, for example, can improve targeting and identify overpressured zones ahead of the bit. Aminzadeh holds the patent for a method of guiding oscillating wellbores during drilling with seismic data from energy generated by the drillbit and recorded by geophones in the well being drilled or in a nearby well.

Improvements are still needed in the imaging of geologic strata below salt, basalt, and other hard rocks, he notes. Research has yielded solutions to some of the sonic-velocity problems that confound the positioning of reflections below complex structures. Further improvements might come from surveys that use “very, very large offsets to shoot underneath these otherwise impermeable [salt] boundaries.”

Another area ripe for further improvement is imaging of fractures and “a better understanding of hydrocarbon-bearing fractures vs. closed fractures,” Aminzadeh says.

Unconventional oil and gas resources represent an area in which “geophysicists have a big role to play.” The SEG president says, “Our members need to push the limits of application areas of their technologies outside the conventional resources.”

Emerging microseismic techniques might help with the imaging of fractures and unconventional reservoirs, such as tight shales and coalbed methane. In microseismic work, geophones continuously record energy from natural vibrations in the subsurface or from field operations such as frac jobs and production.

Other trends Aminzadeh considers important are the increased availability of open-source software, which brings new tools quickly to practical use.

‘Geomentoring’

With technology moving in so many directions and with rapid demographic changes in the industry workforce, the new SEG president proposes a program he calls “geomentoring.”

The age distribution of the SEG membership has “a large hole” in the 30-45-year range, he notes.

“My vision of geomentoring is a program that would cover a large spectrum: technical issues, career issues, and many other things, including how to become active in professional societies, how to publish, how to decide on a career path, how to define ‘success’ for yourself, how to reach that success, among other things,” Aminzadeh says.

“The challenge is how best to channel the large reservoir of wisdom and experience with a strong sense of altruism that our more senior members have to those who can benefit from them. If successful, the result will be a self-perpetuating fountain of geophysical knowledge.”

Aminzadeh notes that a recent SEG investment in online capability will help advance the vision.

“That’s one thing I’m very keen on,” he says.

Career highlights

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Fred Aminzadeh is president and chief executive officer of dGB-USA, Sugar Land, Tex., and president of the Society of Exploration Geophysicists.

Employment
Aminzadeh has held his current position with dGB-USA since 1999. Before joining dGB he worked 17 years with Unocal Corp. in various positions, including manager of geophysical technology. He has written 11 books and holds many patents. He has been an adjunct professor at Rice University and a consultant to several US national laboratories.

Education
He holds a PhD in geophysics from the University of Southern California. His dissertation was on elastic wave modeling, with applications in AVO and elastic impedance calculation.

Affiliations
Aminzadeh has been a member of SEG for 30 years and is a past chairman of the SEG Research Committee and vice-chairman of the Global Affairs Committee. He served as SEG vice-president in 2001-02 and received SEG’s Special Commendation Award in 1998. He also belongs to the American Association of Petroleum Geologists, Society of Petroleum Engineers, and European Association of Geoscientists and Engineers. He has served on the National Research Council Committee on Seismology and currently serves on the Department of Energy’s Unconventional Research Technology Advisory Committee. He is a fellow of the Institute of Electrical and Electronics Engineers and a member of the Azerbaijan Oil Academy and Russian Academy of Natural Sciences.