1. A Fiber-Optic Borehole Seismic
A Fiber-Optic Borehole Seismic
Vector Sensor System for Geothermal Site
Characterization and Monitoring
New Subsurface Signals are Needed for Improved Imaging
Björn N.P. Paulsson, Ph.D.
Paulsson, Inc. (PI)
February 18, 2016

2. Seismology The Standard Technology in the Oil & Gas Industry to:
Map the hydrocarbon reservoirs prior to drilling
Map fluid flow and fluid boundaries
Map faults and fractures
NO WELLS ARE DRILLED WITHOUT SEISMIC DATA
Apply seismic technology to Geothermal Energy Resources:
But:
Geothermal reservoirs much more complex so
We need new and better data – in order to get better data we need better instruments and deploy them in boreholes.

3. What is needed to better understand Geothermal Reservoirs?
Need to:
Map permeability and stress distribution in the reservoirs
Map fluid flow and fluid boundaries
Map faults and fractures
If this can be done:
It will result in higher productivity wells and fewer non-productive wells = much better economics.
But:
We need new and better data

4. For Geothermal Reservoirs We have Developed Better Sensors that are deployable at temperatures up to 300°C!

5. Large Seismic Vector Array Technology
Fiber Optic Seismic Sensors
Borehole Seismology

6. Effective & Accurate Monitoring of Geothermal Ops

7. Micro Seismic
Applications
For Long Arrays

8. SAFOD Survey Area At this rate Los Angeles will be next to
SAFOD: San Andreas Fault Observatory at Depth
At this rate Los Angeles will be next to
San Francisco in 11.3 million years
( mm/year (LAX – SFO))
Zoback (2006)

9. A Micro-Seismic Event (4/30/2005 18:49)
PI: M-1.3
MD (m)
MD (m) FT FT FN FN V V
~ M-1.3
Time (ms)
Time (ms)

10. A Micro-earthquake Event in PASO (4/30/2005 18:49:59)
PI: M-1.3
H.R.S.N.
E | N | V
PASO Vertical
PASO North
PASO East

11. Surface Monitoring vs Borehole Monitoring
VSP: 3 faults mapped
Surface Seismic Network: 1 fault mapped
Blue: PASO
Green: VSP pulling FB
Red: VSP pushing FB
Amplitudes are not comparable between PASO & VSP

12. Imaging an Onshore Gas Reservoir

13. 160 level 3D VSP Image. Terminations tie depositional framework.
Geetan et al., 2011

14. 160 level 3D VSP Image. Terminations tie depositional framework.
Geetan et al., 2011

15. Time Lapse Data Monitoring of CO2 injection for Enhanced Oil Recovery in 2002 - 2003

16. Time lapse surveys to monitor CO2 Injection
Depth Amplitude Maps at 4,800 ft showing the CO2 Plume
Baseline – 2002
Monitor – 2003 after 18 months
Increased reflectivity in the Monitor Survey 2003 at a depth of 4,800 ft at the well is due to the injected CO2. Also seen is the increased reflectivity around the water injector wells.
O’Brien et al., 2004

17. Sensor Response and Bandwidth
Great Results -
but Limited by the
Sensor Response and Bandwidth

18. Large Seismic Array Technology
Fiber Optic Seismic Sensors
Borehole Seismology

19. Fiber Optic Seismic Sensor (FOSS) Tests 77°F- 608°F
Tap tests while in oven
25°C
50°C
100°C
150°C
200°C
250°C
270°C
320°C
0 – 6,000 Hz °C

20. Fiber Optic Sensor Development
Deployment System Development

21. Deploying the Fiber Optic Seismic Sensor (FOSS)™ Array into a Well in Texas

22. Very Small TNT Shots Recorded on FOSS @ 1,200 ft (400 m) Distance (Filter: 80-100-1500-2000 Hz):
True Amplitude
0.65 gram
0.97 gram
1.30 gram
1.62 gram
1.94 gram
2.26 gram
= .22 caliper cartridge
2.59 gram
source direction
Outstanding Vector Fidelity
Assuming 90% of TNT energy go into tube waves =
200 Joules from 0.65 gram of TNT = Magnitude M-2.6

23. Data by Optical Sensor Systems
Today:
Seismic – Fiber Optic Vector Sensors (Sensitivity: 100 x Geophones and >1000 x DAS)
P-wave Velocities
SH and SV Velocities
Reflections
Acoustic – Distributed (DAS) for velocity
Temperature – Distributed (DTS) along the fiber
Pressure – Point Sensors
Future:
Chemical Sensors
Pressure sensor – Distributed (DPS)
Magnetic, Electro Magnetic, Resistivity

24. Borehole Seismic Survey Benefits to Geothermal Reservoirs
Map permeability and fluid distribution in the geothermal reservoir
Map fluid flow and fluid boundaries
Map faults and fractures
This will result in higher productivity wells and fewer poor wells
Specifically
Mapping Micro Seismic locations with improved signal/noise ratios
Understanding of the physical mechanisms of faulting and fracturing
Subsurface imaging with multi-level high-temperature tolerant fiber-optical sensors
Apply improved hypocenter determination and improved imaging to refinements of our 3D structural model
Real time processing will allow us to mitigate the seismicity based on a better understanding of fault mechanisms and fluid flows .

25. Acknowledgement
The research discussed in this presentation has been supported by the following grants:
DOE Contract DE-FE (2010)
RPSEA Contract (2011)
DOE Contract DE-EE (2012)
DOE Contract DE-FE (2014)
California Energy Commission Contract GEO
The support and assistance from these grants made it possible to develop the fiber optic sensor and deployment technology described in this presentation. The support from Karen Kluger for DE-FE , Bill Head for RPSEA Contract , Bill Vandermeer for DE-EE , Bill Fincham for DE-FE and Cheryl Closson for GEO is gratefully acknowledged.

26. Thank You!