Geophysics and Geothermal Energy. Joseph Capriotti Meghan Helper Kendra Johnson Patricia Littman Gordon Osterman

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1 Geophysics and Geothermal Energy Joseph Capriotti Meghan Helper Kendra Johnson Patricia Littman Gordon Osterman

2 Colorado School of Mines End of students junior year 4 week field camp Learning experience for undergraduates

3 Acknowledgments Ben Northcutt All the students of Summer Field Camp Richard Krahebuhl Advisor / Research Professor Mike Batzle - Field Camp Head Terry Young - Geophysics Department Head Andre Revil Associate Professor Robert Raynolds - Field Camp Head Geologist Rachel Vest Woolf

4 Locations Neal Hot Springs Upper Arkansas Valley

5 Finding Geothermal Resources Geophysics: Variety of properties to characterize resource Basic physical properties Imaging the subsurface structure Imaging fluids

6 Physical Properties Property Density Magnetic Susceptibility Conductivity Velocity Method Gravity, Seismic Magnetics DC Resistivity, Self Potential, Electromagnetic Seismic

7 General Surveying Tactics/Commentary Run lines perpendicular to (supposed) anomaly 3D vs. 2D Non-unique solutions = many methods Surface clues

8 Neal Hot Springs Survey Lines Raynolds, 2011

9 Geophysics and Geothermal Systems Where is the hot water? How can it flow to the surface?

10 Figure: The set up and theory behind DC resistivity (Northwest Geophysical Associates Inc.) Where is the water? Inject current into ground Measure potential difference Calculate apparent resistivity Invert for resistivity/conductivity model Water = conductive! DC Resistivity

11 Self Potential Theory Revil, 2011

12 Self Potential Positive self potential anomaly Negative self potential anomaly

13 Frequency Domain Electromagnetics Transmitter coil (Tx) Receiver coil (Rx) current Primary field Secondary field

14 Time Domain Electromagnetics TEM acquisition setup from North Carolina Division of Water Resources Station 2 Central Sounding

15 Gravity Gravity: local subsurface density changes

16 Magnetics Magnetics: subsurface composition, magnetic susceptibility changes

17 Seismic Reflections from velocity contrast between beds

18 Upper Arkansas Valley Investigations Poncha Springs Courtesy of Dr. Andre Revil

19 Aeromagnetics V.J.S. Grauch & Benjamin Drenth, Airborne Geophysical Results, USGS, April 2009

20 Aeromagnetics N Poncha Springs Survey Area Aeromagnetic Map V.J.S. Grauch & Benjamin Drenth, Airborne Geophysical Results, USGS, April 2009

21 Aeromagnetics N Gradient Window Residual Analysis V.J.S. Grauch & Benjamin Drenth, Airborne Geophysical Results, USGS, April 2009

22 Aeromagnetics N Fault Interpretation V.J.S. Grauch & Benjamin Drenth, Airborne Geophysical Results, USGS, April 2009

23 Aeromagnetics N V.J.S. Grauch & Benjamin Drenth, Airborne Geophysical Results, USGS, April 2009

24 Joint Gravity, Magnetic and Seismic Interpretation N Survey Line Poncha Springs Google Earth Courtesy of Dr. Andre Revil

25 2009 Field Camp Deep Seismic Line

26 Grav, Mag, Seismic integration with GM-SYS under academic license for course use only

27 2009 Field Camp Gravity, Magnetics, and Seismic Joint Interpretation Grav, Mag, Seismic integration with GM-SYS under academic license for course use only

28 DC Resitivity and Self Potential Joint Interpretation N Chalk Cliffs Survey Line Google Earth

29 Temperature Data Self-Potential Data Resistivity Model Courtesy of Dr. Andre Revil

30 4±1 x10 3 m 3 /day of thermal water upwelling Courtesy of Dr. Andre Revil

31 Neal Hot Springs Investigation Raynolds, 2011

32 Gravity 3D inversion of 2007 gravity data (Geothermal, Inc.). Inverted with Gzinv3d, created at UBC-GIF based on (Li and Oldenburg, 1998); Algorithm Teaching License provided to CSM-CGEM for academic use only.

Gravity Raynolds, 2011 3D inversion of 2007 gravity data (Geothermal, Inc.).

33 Gravity Raynolds, D inversion of 2007 gravity data (Geothermal, Inc.). Inverted with Gzinv3d, created at UBC-GIF based on (Li and Oldenburg, 1998); Algorithm Teaching License provided to CSM-CGEM for academic use only.

34 Gravity and Seismic Data Gravity

35 Neal Hot Spring EM Results

36 Resistivity: Profile 3 Results

37 Resistivity: Profile 3 Results SP Time-domain EM Resistivity Distance along profile (m)

38 Resistivity: Profile 4 Results SP Resistivity

39 What are we looking for? It s the fluids that count Mike Batzle M. Batzle. Fracturing and sealing in geothermal systems. PhD thesis, MIT, Cambridge, MA, 1978.

40 Using data to find Geothermal sources Courtesy of Andre Revil Grav, Mag, Seismic integration with GM-SYS under academic license for course use only

41 Correlation: Geology, Gravity, DC

42 Correlation is Confidence

Preliminary results for a near surface 3D seismic survey of a geothermal system in Colorado

Preliminary results for a near surface 3D seismic survey of a geothermal system in Colorado Andrew Lamb 1, Kasper van Wijk 1, Lee Liberty 1, Mike Batzle 2, André Revil 2, Kyle Richards 2 and Chuck Diggins