1

Earthquakes Triggered byUnconventional Oil and Gas

Development

Mark D. ZobackProfessor of Geophysics

Director

U.S. Natural Gas Production(billions of cubic feet per day)

ShaleGas

Non-Shale Gas

20

30

40

50

60

70

2000

2003

2006

2009

2012

Unconventional

Conventional

2005

U.S. Oil Production(million barrels per day)

2

4

6

8

10

1949

1957

1965

1973

1981

1989

1997

2005

2013

ConventionalDecline Curve

Source: U.S. Department of Energy, Energy Information Administration (EIA)

~1/2 Coal

~25% Recovery <10% Recovery

Unconventional Gas and Tight Oil Development

Palo DuroWoodford

AvalonAvalon

Barnett24-252 TcfBarnett24-252 Tcf

Haynesville(Shreveport/Louisiana)29-39 Tcf

Haynesville(Shreveport/Louisiana)29-39 Tcf

Fayetteville20 TcfFayetteville20 Tcf

Floyd/Conasauga

Niobrara/Mowry

CaneCreekMonterey

Michigan Basin

UticaShale

Horton BluffFormation

New Albany86-160 TcfNew Albany86-160 Tcf

Marcellus225-520 TcfMarcellus225-520 Tcf

Antrim35-160 TcfAntrim35-160 Tcf

Lewis/Mancos97 TcfLewis/Mancos97 Tcf

Green River1.3-2 Trillion BblGreen River1.3-2 Trillion Bbl

Gammon

Colorado Group>300 TcfColorado Group>300 Tcf

Bakken3.65 Billion BblBakken3.65 Billion Bbl

Montney Deep Basin>250 TcfMontney Deep Basin>250 Tcf

Horn River Basin/Cordova Embayment>700 Tcf

Horn River Basin/Cordova Embayment>700 Tcf

0 600

MILESEagle Ford25-100+ TcfeEagle Ford25-100+ Tcfe

OIL SHALE PLAYGAS SHALE PLAY

✓

✓✓

✓

✓✓✓

✓

✓✓✓

Unconventional Gas, NG Liquids and Oil Development

Opportunities and Challenges ofShale Gas Production

The Bridge (U.S. National Academy of Engineering), 2014

Earthquakes in the Mid-Continent

Ellsworth (2013)

Earthquakes in the Mid-Continent

Ellsworth (2013)

Topics

o Earthquake Fundamentals - A Context forUnderstanding Earthquake Triggering

o More Earthquakes in Oklahoma ThanCalifornia?

o Managing Earthquake Risk

I-We Live on aCritically-Stressed Crust

• Earthquakes Occur NearlyEverywhere in Intraplate Areas

• Small Perturbations <RIS>Capable of Triggering Seismicity,Even in “Stable Areas”

Waste InjectionDenver Arsenal

Fluid InjectionRangely Oil Field

II. Fluid Injection Can Induce Earthquakes

A Simple Earthquake Machine

Friction

Block jumps ahead in sudden slip events(like earthquakes) and the stress drops

τ = µ σn σn = Sn - Pp

Prague EarthquakesM ~5.7

Keranen et al. (2013)

III. Earthquake Hazard Depends on Whether Injection IncreasesPore Pressure in Potentially Active Basement Faults

Fault Patch Size (m)

Major: can cause serious damage over large areas.

Moderate: can cause damage to poorly constructed buildings

Minor: felt but does not cause damage

Noticeable shaking but damage is unlikely

Strong: can be destructive in populated areas

Damaging Earthquakes Require Big Faults

EQ stress drop

slip on fault

8

7

6

5

4

3

2

1

0

-1

-2

-3 100 101 102 103 104 105

Earth

quak

e M

agni

tude

IV. Basement Faults That are Potentially Active in theCurrent Stress Field Are Also Hydraulically Conductive

Zoback and Townend (2001)

Zhang et al. (2013)

25,000’

BASEMENT

SHALE

TRIGGERED SEISMICITYWATER DISPOSAL WELLWATER DISPOSAL WELL HORIZONTAL SHALE WELL

SAND

14

EarthStress

M 2.3 Earthquake During HF in Bowland Basin

Topics

o Earthquake Fundamentals - A Context forUnderstanding Earthquake Triggering

o More Earthquakes in Oklahoma ThanCalifornia?

o Managing Earthquake Risk

RemovingOklahomaEarthquakes

- 17

Llenos et al. AGU (2014)

Oklahoma Has Had 69% of the Recent Earthquakes

CA vs OK

- 18

2000 2005 2010 2015

Inje

ctio

nR

ate

inM

illio

nsof

Bar

rels

perM

onth

0

200

400

2.5

3

4

5

6Injection and Earthquakes in Oklahoma

Eart

hqua

keM

agni

tude

SWDUnknownEOR

1998 2000 2002 2004 2006 2008 2010 2012 2014

Cum

ulat

ive

Num

bero

fM

agni

tude

2.5+

Eart

hqua

kes

0

500

1000

1500

2000

2500Cumulative Number of Magnitude 2.5+ Earthquakes in Oklahoma

Prior to 2009M 4 Eqs 1/10 years

M 4 Eqs in 20151/11 days

Walsh and Zoback (2015)

- 19

Massive Injection of Produced Water

Oil and SaltwaterProduction

Salt Water Injectionat 2 – 2.5 km~700 Million Barrels<1 MPa Pressure Change

Earthquakes5-6 km Depth

Areas With Increased Disposal Have Earthquakes

- 21

3 Areas withFew Earthquakes:

3 Areas with 71% of Oklahoma'sEarthquakes

Map

Inje

ctio

n Ra

te in

Mill

ions

of B

arre

ls / M

onth

Inje

ctio

n Ra

te in

Mill

ions

of B

arre

ls / M

onth

Eart

hqua

ke M

agni

tude

Eart

hqua

ke M

agni

tude

2009

2010

2011

2012

2013

2014

Mill

ions

ofB

arre

ls

0

50

100

150

200

250

300

350

CherokeeEOR VolumeSWD volumeFrac Flowback Volume

2009

2010

2011

2012

2013

2014

Mill

ions

ofB

arre

ls

0

50

100

150

200

250

300

350

PerryEOR VolumeSWD volumeFrac Flowback Volume

2009

2010

2011

2012

2013

2014

Mill

ions

ofB

arre

ls0

50

100

150

200

250

300

350

JonesEOR VolumeSWD volumeFrac Flowback Volume

Where Does the Wastewater Come From?

Topics

o Earthquake Fundamentals - A Context forUnderstanding Earthquake Triggering

o More Earthquakes in Oklahoma ThanCalifornia?

o Managing Earthquake Risk

I. Be Proactive

M 2.3 Earthquake During HF inBowland Basin

II. Avoid Injection Near Potentially Active Faults

Consider Water Recycling As in Pennsylvania

27

Thank you