The Frontier Observatory for Research in
Geothermal Energy: A Laboratory for
Enhanced Geothermal System Development

November 20, 2019www.UtahFORGE.com

Conventional Geothermal Systems• In-situ fluid totransport the heat
• Sufficient
permeability fornatural convection
to occur• 40 l/s (15 bpm) flowrate• Drilling represents
50% of project cost

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Enhanced Geothermal Systems• Also called Engineered Geothermal Systems• Lack adequate permeability for convection• Conductive thermal gradients• Create permeability by hydraulic fracturing, thermal
stimulation, or acid dissolution

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45 Years of EGS Stimulations

US (5 sites)
EnglandFranceJapan
Australia
South Korea

Compiled from Tester and others, 2006 and Breed and others, 2013

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Current Status of Enhanced Geothermal SystemDevelopment••••••No EGS systems greater than a few MWe developed
Low flow rates < 40 l/s (<15 bpm) and low heat recoveries
Reactivated fracture zones dominate EGS reservoirs
Open hole stimulations are not effective
Induced seismicity >M3 can lead to project shut down
Thermal effects may be as important as hydraulic effects

Raft River www.UtahFORGE.com
Geothermal Well RRG-9

Phase 1 (2014-2016)• Five sites selected; $400k per site
for desktop characterization 9months duration
Phase 2 (2016-2019)• 2A/B: Two sites selected; $19
million made available for proving
resource and permitting activities• 2C: Utah site chosen for theFORGE laboratory ($10M available)
Phase 3 (2019-2024)• Drill, stimulate and flow test at least
two deep wells; ~ $125 million overthe five years for testing andresearch
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Advancing EGS Development
FORGE will provide opportunities to develop and test:• Novel stimulation and well completion
methodologies to produce fracture networks in hardrocks• High-temperature drilling tools and zonal isolation
technologies in hot crystalline rocks• Techniques to modify/manage existing stress fields totake advantage of existing fractures• Methods to manage and forecast induced seismicity• Best management practices for EGS• TMHC models• Education/research opportunities at all levels
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FORGE Criteria• Temperature >175oC
••
•
•
•

and <225oC
Depths >1.5 km
Low permeability
graniteLow risk frominduced seismicity
Low environmentalrisks
No connection tohydrothermal system
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The Utah FORGE Team

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Utah’s Renewable Energy Corridor
No Endangered Species
No Nearby Human Activity
No Potable Water

3 Geothermal fields; Windfarm; Solar Field, Biogas Facility
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www.UtahFORGE.com

Site Is Data Rich
• More than 100 gradientand deep wells• Detailed geologic
maps, rock samples,gravity, LiDAR, andInSAR surveys, andwater analyses
available• Thermal data frommany wells• Seismic monitoringsince 1981
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Geological Overview

south facing

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west facingWell 58-32•

Completed and tested
well to 2297 m•

Reached a temperatureof 199oC•Ran full suite ofgeophysical and imagelogs•

Conducted
geomechanical tests oncore from two intervals(~6 m)•

Performed Microhydraulic and Diagnostic
Fracture Injection Test(DFIT) in barefoot sectionof well
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Well Stratigraphy & Lithology

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Stress Directions
Natural Frac.

Induced Frac.
Azimuths of induced
fractures from FMI log
Tadpole = natural fracture
Circle = induced fracture
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2017 Injection Program32• 8 injection cycles
over two days
• Injection rates up
to ~1.43 m3/min(~9 bpm)
• Max surfacepressure ~27.6
MPa (~4000 psi)
• Permeability of ~30
microdarcies

451

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Existing Boreholes
Well 68-32 TD 305 m; tools 282 m• 3C 15 Hz geophone (4 sensors percomponent)• 3C Silicon Audio accelerometer

Well 78-32: TD 1000 m; Top of granite 780 m• Schlumberger 12 3C Geophones, 30 m
spacing straddling granite contact• Silixa Distributed Acoustic Sensing cable
Well 58-32• Deep Monitoring Well
• Temperature at 199°C

Distances: 68-72 to 58-32 = 100 m; 78-32 to 58-32 = 362 m
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Stimulation 1: Open Hole
Stimulation 1:• 2240-2294 m (7348•••7525) ft KB
Repeated 2017 tests
and and increased
injection rate from~1.43 to 2.38 m3/min(~9 to 15 bpm)
Breakdown occurred atsurface pressure 24.1
MPa (3500 psig)
Multiple fracture sets
stimulated

G-function plotPdP/dG
GdP/dG

Average Rate
Peak Bottom hole Pressure
Bottom hole Closure Pressure
Frac Gradient

Fracture 1
3.42 bpm 0.54 m3/min
6027 psi
41.6 MPa
5600 psi
38.6 MPa
0.75 psi/ft
15.7 kPa/m

Fracture 2
3.42 bpm 0.54 m3/min
6027 psi
41.6 MPa
4700 psi
32.4 MPa
0.63 psi/ft
13.2 kPa/m

Locations
uncertain

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Stimulation 2: Critically Stressed Fractures
94500

3500

Pressure (psi)

Stimulation 2: Cased hole
• Perforated casing from 21232126 m (6964-6974 ft) KB• Stimulated critically stressed
fractures (NNE-trending)• Fracture breakdown initiatedat injection rate of 0.79
m3/min (5 bpm) for 6 min;surface pressure 28.3 MPa(4100 psig)• Multiple fracture sets
stimulated8Cycle 473000

62500

52000

41500

31000

2500

100160165
Annulus Pressure

Locations
uncertain

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170
Time (minutes)

180

175

Treatment Pressure

Rate

Rate (bpm)4000

Stimulation 3: Non-Critically Stressed Fractures
Zone 3 Cycle 7 (step rate)
6.5
6000

6.0

Bridge PlugFailure

5000

5.5
5.0

4000

4.0

circulating after
packer failure

3.5

3000

3.0
2.5

2000

2.0
1.5

1000

1.0
0.500.0
15:36:00 16:04:48 16:33:36 17:02:24 17:31:12 18:00:00 18:28:48 18:57:36
Tubing Pressure

Annulus Pressure

Rate

Locations
uncertain
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Flow (bpm)

4.5

Pressure (psi)

Stimulation 3: Cased hole
• Perforated casing from2001-2004 m KB (65656575 ft)• Stimulate non-criticallystressed fractures• Fracture breakdown
uncertain before bridge
plug failed at surfacepressure of ~43.4 MPa(~6300 psig)• Microseismic activity
observed in open holesection and lower
perforated zone2020-2024 Activities• Two wells drilled• Interconnectivity• Drill and stimulate
injection/production pair
• Circulate between wells• Monitor reservoir development• 50% of funds for external
research

established at the toe• Active R&D program
even during wellconstruction

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All Data Is In The Public Domain

Earth and Numerical Modelingwww.UtahFORGE.com

THANK YOU

Funding provided by the US Department of Energy with additional support from Utah
School and Institutional Trust Lands Administration, Beaver County, the Governor’s Officeof Energy Development, and Smithfield Foods.
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Earth and Numerical Modeling• Results compiled inTemperature“reference” earth modelusing LeapFrog
Geothermal.
• Box shows FORGE
reservoir and modelingdomain.
• Model will be revised
as FORGE progresses
and additional data arecollected

Top of granite

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Seismic Monitoring: Surface Monitoring• Detect and locate with high••precision, injection related
seismic events
Establish microseismic
monitoring for times of shut-in or
flow tests
Test non-traditional technologies(DAS, Nodals)

Seismometer locations and prestimulation microseismic locations(2016-2019)www.UtahFORGE.com

Nodal Array (150 nodes)

Monitoring Configuration – Depth View
Geometry appropriate for detection, notlocation

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