KEY CONTROLLING FACTORS OF

SHALEGAS INDUCED SEISMICITY

Brecht Wassing, Jan ter Heege, Ellen van der Veer, Loes Buijze

Acknowledgements

This work is part of a project that received funding by the European

Union’s Horizon 2020 research and innovation programme under grant

agreement number 640715 and number 691728. The content of this

poster reflects only the authors’ view. The Innovation and Networks

Executive Agency (INEA) is not responsible for any use that may be

made of the information it contains.

INDUCED SEISMICITY IN M4SHALEGAS

Fault reactivation & induced

seismicity

KEY QUESTIONS

What are the key controlling factors (site-specific and operational) for induced

seismicity (hazard and risk)?

Can we assess the potential for inducing felt earthquakes during shale gas

operations? Upfront, during operations?

(How) can we mitigate induced seismicity?

BLACKPOOL INDUCED SEISMICITY

Key controlling factors of shalegas induced seismicity

Clarke et al., 2014. Felt seismicity associated with shale gas hydraulic fracturing: the first documented

example in Europe.

http://earthquakes.bgs.ac.uk/

research/BlackpoolEarthquakes.html

M 2.3

Vo

lum

e B

BL

Effective normal stress

Shear stress

fault

INJECTION-INDUCED SEISMICITY

WHAT CAN WE LEARN FROM ANALOGUES?

ΔP

Direct pressure effect Volumetric deformation

Failure mechanisms

tensile shear

pressure

increase

expansion

KEY CONTROLLING FACTORS

• Site specific factors: Presence of large faults, natural seismicity, basin

sensitivity to induced seismicity, mechanical rock properties, depth…?

• Operational factors: Planned injection volumes, injection pressures,

injection rates..?

KEY CONTROLLING FACTORS: GEOLOGICAL

KEY CONTROLLING FACTORS: OPERATIONAL

Time after start injection Distance from operation

KEY CONTROLLING FACTORS: OPERATIONAL

Volumetric moment μΔV (Nm)

McGarr, 2014. Maximum magnitude earthquakes induced by fluid injection.

McGarr, 2014: M0,max=μΔV

M0

Atkinson et al., 2016.

Hydraulic fracturing in the Western

Canada Sedimentary Basin.

Se

ism

ic M

om

en

t (Nm

)

Ma

gn

itu

de

Injected fluid volume (m3)

Galis et al., 2017. Two physics based models for estimation

of magnitudes of fluid-injection-induced earthquakes

M0max=μ.ΔV

M0max-arr=γ.ΔV3/2

KEY CONTROLLING FACTORS: OPERATIONAL

shear disp (m)

VOLUMES, PRESSURE DISTURBANCE, RUPTURE EXTENT?

Geomechanical & earthquake rupture modelling

Velocity (m/s)

0 0.02 0.04

0.25

0.20

0.15

0.10

0.05

0

-2600

-2700

-2800

-2900

-3000

-3100

-3200

Dep

th(m

)

ΔP

ΔP

fault

shear disp (m)

VOLUMES, PRESSURE DISTURBANCE, RUPTURE EXTENT?

Geomechanical & earthquake rupture modelling

Velocity (m/s)

0 0.02 0.04

0.25

0.20

0.15

0.10

0.05

0

-2600

-2700

-2800

-2900

-3000

-3100

-3200

Dep

th(m

)

shear disp (m)

VOLUMES, PRESSURE DISTURBANCE, RUPTURE EXTENT?

Geomechanical & earthquake rupture modelling

Velocity (m/s)

0 0.02 0.04

0.25

0.20

0.15

0.10

0.05

0

-2600

-2700

-2800

-2900

-3000

-3100

-3200

Dep

th(m

)

shear disp (m)

VOLUMES, PRESSURE DISTURBANCE, RUPTURE EXTENT?

Geomechanical & earthquake rupture modelling

Velocity (m/s)

0 0.02 0.04

0.25

0.20

0.15

0.10

0.05

0

-2600

-2700

-2800

-2900

-3000

-3100

-3200

Dep

th(m

)

Effect of initial stress?

shear disp (m)

VOLUMES, PRESSURE DISTURBANCE, RUPTURE EXTENT?

Geomechanical & earthquake rupture modelling

Velocity (m/s)

0 0.02 0.04

0.25

0.20

0.15

0.10

0.05

0

-2600

-2700

-2800

-2900

-3000

-3100

-3200

Dep

th(m

)

Effect of fault properties?

shear disp (m)

VOLUMES, PRESSURE DISTURBANCE, RUPTURE EXTENT?

Geomechanical & earthquake rupture modelling

Velocity (m/s)

0 0.02 0.04

0.25

0.20

0.15

0.10

0.05

0

-2600

-2700

-2800

-2900

-3000

-3100

-3200

Dep

th(m

) Link to monitoring data?

Borehole seismometers

CONCLUSIONS & RECOMMENDATIONS

Build further understanding of underlying mechanics of injection-induced seismicity:

coupling of experiments – models – monitoring data

Mitigation:

Mapping of faults and fractures

Avoid injection into or nearby critically stressed (basement) faults

Assess seismicity potential from experience in same geological setting

Minimize ∆P: Reduce injection volumes, apply post-frac flowback

Baseline monitoring of background seismicity

Real-time monitoring of seismicity, locations & magnitudes:

alignment along larger structures other than HF orientation?

sudden increase of seismic magnitudes, changes in frequency-magnitudes?

Establish operational protocols for injection sites – advanced traffic light systems

THANK YOU FOR YOUR ATTENTION

Take a look: TIME.TNO.NL

INJECTION-INDUCED SEISMICITY

WORLDWIDE

WAVE PROPAGATION

Complex reflections along formation boundaries

Lower seismic velocities in Rotliegend

Induced seismicity - geomechanical modelling

Tota

l part

icle

velo

city (

m/s

)

ZE

RO

CA

#1

#2

Rupture propagation Rupture arrest (just after) 0.12 s after rupture arrest

Formation VP VS

Zechstein 4687 2273

Rotliegend 2549 1634

Carboniferous 4157 2434