Environmental and Exploration Geophysics IIpages.geo.wvu.edu/~wilson/geol554/GPR_16/GPR2-09.pdf ·...

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Tom Wilson, Department of Geology and Geography

Environmental and Exploration Geophysics II

[email protected]

Department of Geology and GeographyWest Virginia University

Morgantown, WV

Radar Methods + OddsRadar Methods + Odds--nn--EndsEnds


Thinning layer response and resolution considerations.

The vertical resolution limits encountered in seismic have a nearly identical parallel in GPR

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Horizontal resolution - Huygen’s wavelet & diffraction perspectives the Fresnel zone

Destructive interference

Constructive interference


Horizontal Resolution: The Fresnel Zone

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Tom Wilson, Department of Geology and GeographyPerry-Castaneda Library Map Collection

• Location near Hobbes, NM• West Pearl Queen formation, ~4500 feet deep• About 20 years of oil and gas production• A few years of inactivity• Injection of ~2100 tons CO2 over 2 months• Subsequent production

GPR case history: CO2 leakage at a carbon sequestration pilot.


“MM&V is defined as the capability to measure the amount of CO2 stored at a specific sequestration site, monitor the site for leaks or other deterioration of storage integrity over time, and to verify that the CO2 is stored in a way that is permanent and not harmful to the host ecosystem…Subsurface MM&V involves tracking the fate of the CO2within the geologic formations underlying the earth and possible migration to the surface.”

- Sequestration Roadmap, 2004

MM&V activities cover a lot of ground

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Geologic Setting


The pilot site is located approximately 25 miles southwest of Hobbs, NM. Oil and gas fields in the area are highlighted in red. Scholle (2000) (see http://geoinfo.nmt.edu/staff/scholle/guadalupe.html#genset). An introduction and virtual geologic field trip to the Permian reef complex, Guadalupe and Delaware mountains, New Mexico-West Texas).

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From Carpenter (2005)

• Nine wells in immediate area• Several hundreds in

surrounding area• 3-D seismic survey

First, geologic characterization of deep strata for carbon sequestration


Geophysicists/geologists provide the reservoir model

• Porosity and permeability maps generated• Production history• 4-D seismic for validation

Simulation of flow in complex reservoirs

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Short photo lineaments (yellow) are shown on an orthophoto of the test site. The locations of injection well (red) and capillary absorption tube samplers (black) are spotted on the photo.

Remote sensing evaluation of structural imprint


Rose diagram of photolineaments picked from a contrast enhanced digital copy of a 1949 black and white aerial photo of the area (left)

surrounding the West Pearl Queen pilot injection well and orthophoto on the right

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GPR unitSensors & Software Inc. –

Smart CartVisit http://www.sensoft.ca/

Looking into the near-surface depositional environments


Shallow Diffraction

Diffraction with

velocity of 0.19m/nsShallow

Diffraction

Diffraction with

velocity of 0.19m/ns

Diffraction hyperbola having a velocity of 0.19 m/ns is displayed next to a shallow diffraction originating in the near surface sand cover.

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West Pearl Queen Field Area


Hall (2002)Phillips (1999)

The Mescalero caliche is a calcified soil horizon that developed throughout the area about 90,000 to 400,000 years ago

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Mescalero caliche

Plio-Pleistocene

Upper MioceneOgallala Group

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Gamma ray log from the Stivason #5 well 400 meters east of the Stivason#4 injection well. The low gamma ray response between 4 and 9 feet subsurface is associated with the Mescalero caliche.

Well control helps even for very shallow exploration targets


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Local Topography in Area of GPR Survey West Pearl Queen Pilot Site

Feet

Elevation data provided by Bob Benson Colorado School of MinesElevations were surveyed for seismic source and receiver locations at the site

You need to know the topography

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Structure on Top of the Mescalero CalicheDerived from Calculated Velocity of 0.2 m/ns

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Structure on Top of Mescalero CalicheCorrection Velocity Set at the Anomalously Low Value of 0.1 m/ns

Relative drop of about 4 feet

Structure and velocity


Stivason #4CO2 injection well

Structure of the Mescalero caliche is superimposed on an orthophoto of the injection site. GPR survey lines are shown in yellow. Locations of the injection well, CATS, and interpreted

faults are also shown.

CATS stands for capillary adsorption tube sampler

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0.020

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0.040

1.050.0100.0150.0200.0- 2 -

250.0300.0350.0374.0SP:

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GPR profile located 275 meters northwest of the injection well illustrates the general character of the reflection events from the Mescalero caliche

observed across the site.


Stivason #5Thickness of the Mescalero calicheestimated from interpreted two-way radar reflection travel times through the caliche using an interval velocity of 0.15m/ns. Interpreted faults/fracture zones and areas of missing caliche are highlighted.

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Missing caliche zone

Missing caliche zone Abrupt thinning and

disappearance of calichereflection events are illustrated

in this GPR profile.


Concentrations of PDCH measured during a 54-day exposure period are superimposed on an orthophoto of the pilot site. The locations of the injection well, CATS, interpreted faults, and eroded caliche areas are shown for reference.

Perfluorocarbon tracers (PFCs)

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PTCH concentrations measured during the 54-day exposure period.


PDCB concentrations measured during the 54 day exposure period.

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Characterization: Surface to reservoir


Mechanical Layer Formation

Depth to Topft

Depth to Baseft

Thicknessft

Average Densityg/cm3

Average Poisson's Ratio

Young's Modulus (Pascals)

1 Ogallala 0 98 98 1.66 0.30 4.79x107

2 Chinle 98 853 755 1.76 0.257 1.94x1010

3 Santa Rosa 853 1336 483 2.00 0.29 2.76x1010

4 Tri/Perm undiff. 1336 1714 378 2.56 0.24 1.53x1010

5 Rustler 1714 1907 193 2.48 0.30 6.39x1010

6 Salado and Castile 1907 3317 1410 2.11 0.324 3.59x1010

7 Tansill 3317 3523 206 2.92 0.297 7.01 x1010

8 Yates 3523 3810 287 2.87 0.293 6.44 x1010

9 Upper Seven Rivers 3810 3975 165 2.63 0.282 4.8 x1010

10 Lower Seven Rivers 3975 4484 509 2.77 0.289 7.81 x1010

11 Upper Queen/Shattuck 4484 4538 54 2.54 0.249 4.13 x1010

12 Lower Queen 4538 5026 488 2.77 0.288 7.86 x1010

13 Grayburg 5026 5125 99 2.84 0.297 9.54 x1010

Mechanical properties

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Figure 8. Vertical Displacement at Ground Surface

Displacement at t = 150 days

Displacement at t = 53 days

Geomechanical Simulations

Bromhal et al. (2005)


• Atmospheric transport • Diffusion in near-surface

Near-surface flow models can help in locating samplers, examining results.

Bromhal et al. (2005)

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On the way to Pump Canyon


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The CO2 injection well

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11m Massive Sand

1.2m Shale

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Locating near-surface migration pathways using terrain conductivity data


From Pinnacle (2009)

Surface deformation from CO2 injection? Tiltmeter observations

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Modelers view the Fruitland as a series of three coals that have uniform thickness throughout the area.

Fassett’s (1997) regional correlations indicate presence of considerable stratigraphic heterogeneity on a regional scale

Regional cross section from Fassett (1997) spans about 3 miles


Laura Wray (2000)

Individual log and generalized schematic representations of the reservoir

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3D Seismic suggests the reservoir is much more complex


Local discontinuity

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Tuning cube and spectral decomposition


Frequency slicing

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Environmental and Exploration Geophysics IIpages.geo.wvu.edu/~wilson/geol554/GPR_16/GPR2-09.pdf ·...

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