Geologist or geophysicist?
With seismic, the lines
are blurred.
"The geologist/geophysicist distinction is fading
to 'geoscientist,' because a lot of geologists are doing seismic
interpretation now," said Mike Bahorich.
Bahorich is executive vice president-E&P technology
for Apache Corp. in Houston, an AAPG member and president of the
Society of Exploration Geophysicists (SEG) for 2003.
As part of his duties as SEG president, he will be
speaking on "The Road Ahead for 3-D Seismic" around the world.
And with that in mind, he outlined for the EXPLORER
nine areas of coming seismic advances, in computing, digital recording,
massive channel counts, 3-D imaging, time-lapse 4-D, anisotropy,
seismic attributes, multicomponent recording and visualization.
Bahorich gained fame for his work at Amoco in developing
the seismic coherence cube, introduced in 1995. It was the most
recent big-idea breakthrough in geophysics.
"Almost all of the technologies that are of significant
benefit to us today have been known and worked on for years," he
said. "The cycle time from development to 50 percent penetration
in the industry is often five to 10 years."
As an example, he cited the recent introduction by
Input/Output Inc. of digital multicomponent recording hardware,
a technology heralded for over a decade but only now becoming commercially
available.
Pete Maxwell is commercialization manager for Input/Output's
VectorSeis® multicomponent products in Houston. The company
has spent 15 years in developing the technology.
After initial work was complete, about four years
ago, it then conducted more than 30 field tests in cooperation with
Veritas DGC, plus other tests across Europe and one in China, Maxwell
said.
Input/Output made its first sale of the technology
in November, to China National Petroleum Corp. subsidiary BGP.
New advances in geophysics will be vital for the
industry to meet global energy demands, Bahorich noted.
"The E&P industry is facing a tremendous challenge,
to add 37 million barrels (of production) a day over the next decade,"
he said. "Advances in 3-D seismic will play a significant role in
meeting that challenge."
Bahorich predicts meaningful developments in the
following areas:
➤ Computing.
Look for declining storage costs, transmission costs and costs
per cycle. "As those drop, we're going to see a number of benefits,"
he said.
"You'll see more thin-client application use. You'll see interpretations
being done at home more often. You'll also see software that quickly
accesses prestack data over a network."
Faster speeds and lower costs will benefit algorithms like prestack
wave-equation depth migration. Archival storage of prestack data
on disc will allow quicker analysis.
➤ Digital Recording.
"Even today, on almost every seismic survey the initial recording
is an analog signal recorded by a coil and magnet in a geophone,"
Bahorich said.
By contrast, digital recording provides the potential for a
lighter system with better dynamic range and higher fidelity.
A few digital geophones with chips are in use right now, he
believes, and the number will increase as costs come down.
➤ Massive Channel Counts.
Bahorich looks for another big jump in channel counts as technology
improves.
"For years we recorded 48 channels, and then we went to 96,
often used in a 2-D split spread geometry," he said. "When we
went to 3-D we started with these small channels."
That count grew into the hundreds, then reached the 1,000-channel
point, and Bahorich expects the increase to continue.
"I think we'll be seeing in the future channel counts in the
10,000 to 20,000 channel range," he said.
Increased channel counts could lead to the elimination of field
arrays, with arrays being formed and analyzed in the computer.
"You can do smart array forming and resolve problems in the
presence of significant surface static. Improved wave-field sampling
give you a better signal-to-noise ratio, resulting in a better
image," he added.
➤ 3-D Imaging.
As computing costs come down and speeds increase, complex algorithms
will be used more widely, to the benefit of imaging and interpretation.
"The new wave-equation, depth-migration methods are expensive
now, but they offer a more accurate solution," Bahorich said,
"especially in the presence of rapid velocity variation associated
with salt features."
➤ Time-Lapse 4-D.
"I think time-lapse will continue to expand. One of the things
people don't realize about time-lapse is that it's still largely
confined to the North Sea," Bahorich noted.
Little 4-D seismic work now occurs in the Gulf of Mexico shelf,
where only a few companies monitor reservoirs with a series of
3-D seismic acquisitions.
"As 4-D becomes more common and cheaper to implement, you'll
see it spread beyond the North Sea and deepwater plays," he said.
➤ Anisotropy.
In general, geophysicists ignore the fact that the velocity
of sound waves varies with direction, according to Bahorich.
"We know that the subsurface is heterogeneous, but we've always
assumed that each little unit is isotropic," he said. "Over the
next five years you'll begin to see more algorithms that correct
for anisotropy."
Techniques exist for handling anisotropy, but they may not be
well understood — and aren't often applied.
"This is an example of a technology that's underutilized, in
my mind," Bahorich said. "We have some tools to correct for anisotropy,
but we generally ignore it."
➤ Seismic Attributes.
Mathematical inversion of seismic attributes to rock properties
will increasingly aid interpretation, Bahorich predicted.
When attributes are tied to well control they can be correlated
to petrophysical properties, enabling the interpreter to identify
and associate high correlations with specific properties, like
porosity.
"We have new techniques using neural networks to do this more
rapidly and efficiently," he said.
➤ Multicomponent Recording.
After years of talk, the industry is finally seeing lighter-weight,
multicomponent recording hardware in the introduction stage.
Multicomponent devices record sound in three orthogonal directions,
picking up P-wave and shear-wave information.
"The converted shear-wave data allows you to look through gas
clouds. Sometimes your structure map can look like a doughnut
— the center is depressed because of all the gas," Bahorich said.
Input/Output claims its new hardware will not only provide better
views below gas clouds and salt, but also help predict lithology
and fluid type and provide better fracture and stress identification.
With its improved lithology/fluid discrimination, the technology
might even be used to calibrate bright spots, Bahorich said.
➤ Visualization.
Something positive about computer games for kids?
"Graphic cards keep getting better and better" as those games
become more sophisticated, Bahorich said. That results in better
seismic displays on the desktop.
"Visualization systems tend to allow you to animate through
data very rapidly," he said. "This is important because we're
predators. Our eye is trained to see things in motion.
"As you go from one line to the next, things change. You can
spot anomalies much more quickly when they are in motion."
Large-screen displays allow collaboration in seismic interpretation,
and the costs don't have to be extravagant, according to Bahorich.
He said collaboration can be done with a PC and a $5,000 projector.
"There have been some spectacular failures in this area," he
noted. "The business model of setting up a million-dollar visualization
room and renting it out to companies has not done well.
"You will be able to get a better visualization set-up for $25,000
in 2005 than you could have for $1 million in 1995."
As geologists add seismic interpretation to their
professional toolkits, it's important for them to understand and
utilize advances in geophysics, said Bahorich.
"Geologists should stay up with the latest technology,
to be able to use the best tools for whatever problem is being faced,"
he said.
Bahorich noted that this knowledge can be acquired
from a number of sources, including training sessions, professional
papers, industry publications and the World Wide Web — not to mention
the short courses and other support available from professional
societies like SEG and AAPG.
"The individual geoscientist can find some fantastic
resources," he said. "Bright people take advantage of what professional
societies offer."