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

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.

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

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

Large Seismic Vector Array Technology Fiber Optic Seismic Sensors Borehole Seismology

Effective & Accurate Monitoring of Geothermal Ops

Micro Seismic Applications For Long Arrays

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 (543 km @ 48 mm/year (LAX – SFO)) Zoback (2006)

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)

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

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

Imaging an Onshore Gas Reservoir

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

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

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

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

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

Large Seismic Array Technology Fiber Optic Seismic Sensors Borehole Seismology

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

Fiber Optic Sensor Development Deployment System Development

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

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

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

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 .

Acknowledgement The research discussed in this presentation has been supported by the following grants: DOE Contract DE-FE0004522 (2010) RPSEA Contract 09121-3700-02 (2011) DOE Contract DE-EE0005509 (2012) DOE Contract DE-FE0024360 (2014) California Energy Commission Contract GEO-14-001 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-FE0004522, Bill Head for RPSEA Contract 09121-3700-2, Bill Vandermeer for DE-EE0005509, Bill Fincham for DE-FE0024360 and Cheryl Closson for GEO-14-001 is gratefully acknowledged.

Thank You! www.paulsson.com