(VSP) efforts in the injection well. Site

Comments

Transcription

(VSP) efforts in the injection well. Site
Site Characterization Activities with a focus on NETL MMV efforts: Southwest Regional
Partnership, San Juan Basin Pilot, New Mexico
Thomas H. Wilson1,2 e-mail: [email protected]; Art Wells1, Henry Rauch1,2, Brian Strazisar1, and Rod Diehl1 – 1) National Energy Technology Center; 2) West Virginia University
Objective
Site Background
A variety of characterization activities have been undertaken on
the Southwest Regional Carbon Sequestration Partnership’s San
Juan Basin pilot site to aid in the deployment and subsequent
interpretation of the National Energy Technology Laboratory’s
MMV tracer and soil gas monitoring efforts. Approximately 75,000
tons of CO2 will be injected in the basal Fruitland coal at a depth of
approximately 3500 feet.
Site characterization activities included field and satellite based
fracture mapping, subsurface mapping of the region using
geophysical logs, evaluation of interferrometric synthetic aperture
radar (INSAR) measurements of ground movements at the site,
detailed electromagnetic surveys, lineament analysis of radar and
Landsat imagery, design of a near-surface ground water
monitoring well program and the design of detailed logging and
vertical seismic profiling (VSP) efforts in the injection well.
Structure on the Fruitland coal across the pilot site (map at left) is
nearly flat and dips approximately 0.25oNE toward the axis of the San
Juan basin. The Fruitland Formation is about 175 feet thick in the area
and contains three coals with net thickness of about 55 to 60 feet. CO2
will be injected in all three coals. Subsurface mapping suggests that
significant faults and fracture zones are not present at the site. Surface
and satellite based fracture mapping reveal the presence of two
systematic fracture sets with dominant NE and NW trends (far right).
Surface fracture trends are consistent with butt and face cleat trends
observed in core through the Fruitland from a nearby well. The face
cleat in the area have NE trend. Surface observations also included
acquisition of over 50 line-kilometers of EM data used to help locate
potential near-surface fracture zones (right). Placement of additional
tracer and soil gas sample points was recommended based on fracture
trend and the near-surface distribution of low-conductivity anomalies.
Henthorn, et al. (2007)
INSAR experiment designed to detect production induced surface subsidence
~200feet
11m Massive Sand
San Juan
Basin pilot site
surface
geology
1.2m Shale
1.2 m shale beneath upper
massive sand
The sandstone holding up the mesa is approximately 11 meters
thick and deposited over a relatively thin shale. The sandstones and
shales in this Eocene age deposit extend several hundred feet
beneath the surface. The near-surface stratigraphy throughout the
region is characterized by canyon cut mesas whose edges consist
of a series of sandstone steps and benches.
Satellite based radar scenes of the
site were collected multiple times
over a three month interval in 2006
to determine whether surface
deflation was occurring in response
to hydrocarbon production in the
area. INSAR observations revealed
strong coherence between images
but no surface deformation. The
experiment demonstrated the
viability of the technique. The
partnership is currently collecting
monthly images to compliment
surface tiltmeter observations over
the site.
Logging and synthetic seismogram
Fast shear azimuth inferred
from the Schlumberger
Sonic Scanner trends
roughly perpendicular to the
axis of the basin.
Rose diagram of drilling
induced break outs
observed in the
Schlumberger FMI log.
Synthetic seismic response of the logged
intervals 300 feet to 2890 subsurface.
Detailed logging of the injection well is planned and
includes the FMI log for detailed fracture
characterization and the sonic scanner to obtain
mechanical properties and measure sonic anisotropy.
One zero offset and three offset VSPs will also be
collected prior to and during injection to determine
whether the presence of CO2 can be detected and its
movements monitored. The VSP may also yield evidence
of small scale faults and fracture zones and help the
NETL MMV team interpret post-injection observations.
The geophysical logging and VSP data will help other
NETL and SWP researchers develop geomechanical and
flow models.
Regional and local INSAR displacement maps
SWP Vertical Seismic Profile
Three offset VSPs and one zero offset VSP
were collected at the site prior to injection. The
source point locations are shown on the
QuickBird image at left (red circles). The
orange circle has a diameter of 1500 feet, the
optimal VSP source offset. Presence of
archaeologically sensitive areas at the site
limited our choice of offsets, with one
exception, to distances greater than 1500 feet
along less than optimal azimuths. The image at
left also shows locations of wells, NETL tracer
and soil gas sample points and titlmeters
Pre-injection zero offset VSP
corridor stack along with the
offset CDP stacks at three
offsets shown on the location
map. acquired in the CO2
injection well. This data was
collected for the Southwest
Regional Partnership and
processed by Schlumberger.
(VSP displays, courtesy of
Schlumberger, 2008).
Terrain conductivity and fracture characterization
QuickBird fracture trace orientations along the west (left)
and southeast (right) canyons near the new injection well.
Terrain conductivity response, PFC tracer and
soil gas sampling locations
Surface fracture trace orientations along the west (left) and
southeast (right) canyons near the new injection well.
Conclusions
As part of the NETL-University Consortium we initiated several site characterization
activities with the objective of providing feedback to the NETL MMV team regarding
locations of possible CO2 leakage pathways and the optimal placement of monitoring
technologies to optimize estimation of CO2 escape volume if leakage were to occur.
Collaborative efforts were also designed to compliment and enhance ongoing
Partnership efforts. The work discussed in this paper concentrates on collaborative
efforts conducted at the Southwest Regional Partnership’s San Juan Basin pilot.
Terrain conductivity surveys reveal interconnected low conductivity anomalies in well
drained areas within the massive sand that underlies the site. These low conductivity
zones may facilitate groundwater flow and migration of CO2 to the surface if leakage
occurs. Based on the results of the terrain conductivity surveys, recommendations
were made to undertake additional tracer and soil gas sampling in these areas.
Log data through the intermediate zone (top of the Fruitland to near-surface)
provide detailed observations of P-wave and S-wave transit times, density, shearwave anisotropy and mechanical properties through 2600 feet of the strata overlying
the injection zone. A synthetic seismogram compiled from the density and sonic logs
provides a preliminary simulation of the subsurface seismic reflection response and
serves as the basis for a preliminary interpretation of events observed in the zerooffset vertical seismic profile (VSP). Future VSP interpretations and modeling may
provide additional insights into the potential for CO2 escape through the intermediate
zone. The planned time-lapse imaging may also reveal the position of the CO2 flood
front within the Fruitland coal interval.
The research undertaken in this project helps 1) identify potential leakage zones
and 2) suggests additional locations for NETL monitoring activities. As a contributing
partner in the regional partnership efforts our activities help expand outgrowths of
partnership monitoring efforts by enhancing the monitoring and modeling efforts
conducted both by NETL and the partnerships at individual pilot sites.
Acknowledgements
This technical effort was performed in support of the National Energy Technology Laboratory’s on-going
research in carbon sequestration under the RDS contract DE-AC26-04NT41817-6060404000. We’d like
to thank Dave Wildman and Donald Martello, our DOE-NETL project managers, for their support and
advice on these efforts; Scott Reeves and Brian McPherson of the Southwest Regional Partnership for
their help in facilitating our involvement in the Partnership’s activities on their San Juan Basin carbon
sequestration pilot test and for allowing us to use data collected as part of the pilot effort; and Ryan Frost
and Tom Cochrane of Conoco Phillips for helping facilitate many of the activities on the site. Appreciation
is also extended to Dwight Peters and Marcia Coueslan with Schlumberger for critical assistance in the
design of the logging and VSP acquisition, analysis and processing efforts at the site. We also want to
thank Bill O’Doud (NETL) for his review comments.
References
• Henthorn, B., Wilson, T., and Wells, A., 2007, Subsurface Characterization of a Carbon
Sequestration Pilot Site: San Juan Basin, NM: Annual AAPG Convention, Proceedings CD. See
also http://www.searchanddiscovery.net/documents/2007/07047henthorn /index.htm &
http://www.geo.wvu.edu/~wilson/netl/ HenthornWilson&Wells -07AAPG.pdf
• MDA Geospatial Services, 2007, Evaluation of InSAR technology for monitoring ground
movement in New Mexico: report prepared for Tom Wilson, June 18, 2007, 23p.
• Schlumberger, 2008, Sonic Scanner borehole anisotropy analysis – EPNG COM A ING 1.
• Schlumberger, 2008, Vertical seismic profile – EPNG COM A ING 1 well, Z-axis processing and
display.

Similar documents