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Experimental investigation of injection pressure effects on fault reactivation for CO2 storage

Experimental investigation of injection pressure effects on fault reactivation for CO2 storage

Category
Academic article
Abstract
Laboratory
tests
were
conducted
in
a
triaxial
load
frame
with
acoustic
emission
and
transmission
capability
to
investigate
mechanisms
that
might
be
initiating
the
microseismicity
experienced
in
CO
2
injection
operations.
Although
often
related
to
reactivation
of
mapped
faults
or
local
fracturing
due
to
reduced
injectivity,
the
case
of
the
Illinois
Basin

Decatur
Project
is
used
here
to
illustrate
the
need
for
better
understanding
of
what
triggers
microseismic
events
in
relatively
large
permeability,
good
reservoir
candidates.
There,
microseismicity
has
oc-
curred
in
the
CO
2
storage
target
formation,
the
Mt.
Simon
sandstone,
as
well
as
in
the
underlying
Precambrian
basement.
The
microseismicity
in
the
Mt.
Simon
sandstone
occurred
ahead
of
CO
2
plume
arrival
and
at
relatively
low
injection
pressure
conditions,
well
below
the
fracturing
pressure
at
the
injection
well.
A
hypothesis
is
suggested
for
the
occurrence
of
such
events
in
the
field,
whereby
critically
stressed
planes
are
activated
by
the
passage
of
the
pressure
front
at
injection
start;
these
faults
are
small
and
thus
not
visible
in
the
seismic
survey.
In
order
to
test
this
hypothesis,
sandstone
plugs
were
prepared
by
two
different
methods
to
incorporate
a
fracture
plane,
which
we
attempted
to
reactivate
by
pore
pressure
pulses.
The
reactivation
was
successful
at
low
pressure
for
a
fracture
created
in
the
laboratory
at
reservoir
conditions
but
was
unsuccessful
except
at
a
much
higher
pore
pressure
in
a
saw-cut
artificial
fracture.
The
results
suggest
that
tortuous,
rough
stress-induced
fractures
may
be
easier
to
reactivate
because
of
the
higher
probability
that
sections
are
already
favorably
oriented
with
respect
to
critical
shear
stress
at
a
low
pore
pressure
increase.
Saw-cut
fractures
may
close
completely
under
isotropic
stress
loading
and
may
be
difficult
to
activate
unless
exactly
oriented
with
respect
to
critical
shear
stress
at
a
low
pore
pressure
increase.
Acoustic
emission
accompanying
fracture
reactivation
was
also
recorded
and
analyzed.
This
revealed
a
di
fferent
event
distribution
energy
between
creating
and
reactivating
the
fracture
Client
  • Other / DE-FC26-05NT42588
Language
English
Author(s)
Affiliation
  • SINTEF Industry / Petroleum
  • USA
  • NORSAR - The Norwegian Seismic Array
  • University of Illinois at Urbana-Champaign
Year
Published in
International Journal of Greenhouse Gas Control
ISSN
1750-5836
Publisher
Elsevier
Volume
78
Page(s)
218 - 227