February 2008 - Rocky Mountain Association of Geologists

Lead Story
Preview: 14th Annual 3-D Seismic Symposium
Monday, March 17, 2008
Downtown Marriott Hotel - Denver, Colorado
Rocky Mountain Association of Geologists and Denver Geophysical Society
By Ron W. Pritchett, Noble Energy, Inc., and R. Randy Ray, Julander Energy Company
INTRODUCTION
This popular one-day symposium will deliver outstanding examples of 3-D seismic applied for oil and gas prospects
in the Rockies. This year, the planning committee also selected areas beyond the Rockies that showcase resource
plays or methods that lead to success in seismic prospecting. The theme, for example – “Seismic for UnConventional
Plays”– proclaims the transition of non-conventional plays to be considered as conventional resources with significant
help from 3-D seismic technology.
Kickoff speaker is Peggy
Williams, Senior Exploration Editor of
Hart’s Oil and Gas Investor Magazine,
who will present “Exploration Trends
across the Globe, the Continent, and
the Rockies.” Profound changes in
the petroleum business are driven
by higher commodity prices, and
Williams will review findings on four
continents, highlighting development
in North America that will be of
interest to growing companies. In
the lunch hour, keynote Speaker
is Larry Lunardi, VP Geophysics for
Chesapeake Energy, who will inform
and enlighten with “3-D Seismic for
Unconventional Resource Plays.”
Dan Donoho (Donoho Oil &
Gas Consultants, LLC) will present
“3-D Reservoir Characterization of
Jurassic Entrada Erg-Margin Facies,
Flat Rock Field, Utah.” In the southern
Uinta Basin, a 27square-mile survey
revealed amplitude anomalies on
reservoir sandstones at a depth
of 11,500 feet. Drilling confirmed
porosity over 20%, and initial
production rates of approximately
2,500 MCFG per day. The seismic
survey was planned and acquired
in rugged terrain, and a pre-stack
model-based inversion provided a
useful forecast for Entrada reservoir
sandstone porosity in a stratigraphic
trap across the area.
How can fracture trends be
accurately mapped? Galen Treadgold
of Weinman GeoScience presents
“Fracture Prospecting with 3-D
Azimuthal Imaging.” Acoustic velocity
in the subsurface changes with
orientation or azimuth as a response
to stress and fractures. Treadgold et
al present a new imaging tool, applied
as pre-migration azimuthal velocity
analysis, that increases resolution of
fracture-permeability drilling targets.
Drilling risk is lower when wells are
located with help from this improved
resolution method, which removes
dip effects and improves the signalto-noise
ratio.
How can reservoir engineers
know shapes and extents of
hydraulic fracturing? Mark Willis,
M a s s a c h u s e t t s I n s t i t u te o f
Technology, will present “Hydraulic
Fracture Quality using Microseismic
and Time-Lapse 3-D VSP Data to
locate Scattered Seismic Energy.”
Using time-lapse 3-D data
obtained during and after hydraulic
fracturing, Willis shows how
microseismic and VSP (vertical
seismic profile) data highlight
scattered seismic events from an
induced fracture. Because gas-filled,
open fractures scatter more seismic
energy than closed fractures, fracture
intensity can be mapped in the region
of induced fracturing. An example of
this technique as applied in Jonah
Field, Wyoming, is shown.
Also related to the developing
giant gas field, Nancy House of
Encana Oil & Gas (USA) will present
“Design through Interpretation of
a Very Large 3-D VSP to Image a
Complex Area in Jonah Field,
Wyoming.” The 6½-square mile
survey led to a new interpretation
o f f a u l t a n d o v e r p r e s s u r e
compartments that will guide drilling
and development. The Encana
team employed up to 42 levels of
3C geophones in a well with an
“associated array length of 2000
feet, at the center of approximately
1,400 surface source points.” The
design allowed higher frequency
Vol. 57, No. 2
6
February 2008