Bi-Monthly Series 1
Thursday, September 29th
8:00am – 9:00am US Central Time
The Road to Achieve Business Value from Borehole Sonic Imaging
Brian
Hornby leads
efforts at Hornby Geophysical Services which focuses on products for downhole
acoustic and elastic wave measurements. Brian achieved his Ph.D. degree at the University of
Cambridge in 1995 and has over 30 years’ experience, beginning as a field
engineer and then moving to R&D roles.
Brian started his career with Schlumberger, ending up with research
scientist positions in Schlumberger-Doll Research and Cambridge Research labs
where he focused on advanced solutions for borehole sonic measurements and Rock
Physics solutions. Next in 1996 Brian joined ARCO and then BP with the merger
where he was a Senior Geophysical Advisor with a focus on borehole geophysics,
including 3D VSP imaging and reservoir monitoring using permanent borehole sensors,
including DAS (Distributed Acoustic Sensing). After BP Brian joined Halliburton in 2016 as Chief
Scientific Advisor for Acoustics where he led efforts focused on advanced borehole
sonic answer products, leaving Halliburton in 2020. Brian’s work experience in both Oil Companies and Oil
Service Companies has given him the background and experience needed to
successfully drive new technologies to a place where commercial success is
achieved.
ABSTRACT: Reflection
sonic
imaging
has been around for decades. However,
there
are still open questions on range
of application and what can be really taken to the bank to
impact our business challenges. Imaging of near-borehole bed boundaries
is well established; however, in many
cases, the results simply reflect what we see from a borehole wall imaging
survey. Of bigger interest is seeing
more complex geology away from the well that is not predictable by borehole measurements. Clear imaging of
faults, overturned beds, and abrupt changes in structure has been demonstrated
— all of interest to those hoping to understand the bigger geologic picture away from the well. Guiding drilling
in horizontal wells with real-time imaging of reservoir boundaries
is another prize that has not yet been achieved but needs to be firmly in the radar.
To further these initial
insights, asset teams need to have a clear workflow to first evaluate and quality control the sonic imaging
processing and then to use and benefit from the new information the borehole sonic image brings to the table. A
key item of course is this “What would we
do differently with the information
from this image?”. To answer this question essential is involvement by
multi-discipline asset team specialists including Petrophysicists, Geologists
and Seismic Interpreters to first quality control the sonic processing and then
to bring an integrated interpretation where the sonic image can be interpreted with confidence.
Beyond
that,
there is strong interest around imaging of fractures. This is a more
controversial topic — here imaging of single fractures simply fails
seismic imaging 101 — which is that the wavelength of the incident wave, for
example, a dipole-induced body wave shear with a wavelength of ~3 m, is much
greater than the size of the fracture, for example, 2 mm for a large fracture. Therefore,
one may conclude that the fracture should be invisible to a
signal of that wavelength. Now the fluid in the fracture does
represent a shear disconnect,
however there will be an instantaneous
conversion of S to P to S
across the fracture as well as a significant part of the fracture will
have both sides touching. Therefore, the fundamental question is this — what size of fractures or cluster of fractures
is needed to deliver reflected energy of sufficient quality so that useful
images can be created away from the well?
In this talk we will
discuss a sonic imaging processing quality control flow to give Operating Company end users understanding and confidence in the result. Sonic imaging examples will be shown, including data from an extended reach/horizonal well acquired by a
drill-pipe conveyed slim-hole sonic and also data from two vertical wells
penetrating flat bedding and high-angle fractures.
Conclusions from these
examples will be given along with thoughts on the Road Ahead. Finally, I will
present a “Traffic lights” display showing, for different target applications,
showing my views on where we are at now, and where we will be going in 1-5 years
and 5 years plus.
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