Plug and abandonment, milling operations and simulations
Master thesis
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http://hdl.handle.net/11250/220923Utgivelsesdato
2014-06-13Metadata
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Sammendrag
During
plug
and
abandonment,
there
can
be
a
need
for
removing
casing
to
ensure
that
a
proper
cement
barrier
can
be
set.
The
conventional
method
for
doing
this
is
by
performing
milling
operations.
Conventional
milling
operations
are
very
time
consuming,
costly
and
also
involves
major
HSE
aspects.
New
technology
for
performing
milling
operations
are
developed
with
the
purpose
to
perform
this
operation
more
safe
and
efficiently.
During
milling
operations
huge
amounts
of
swarf
is
generated.
By
milling
a
section
of
50
meters,
one
can
actually
generate
4
tons
of
swarf!
The
swarf
which
is
basically
metal
cuttings
from
the
milled
casing
has
to
be
transported
away
from
the
platform
site.
Some
platforms
have
their
own
swarf
handling
units
while
others
don’t.
Swarf
may
cause
a
lot
of
damages
to
equipment,
and
people
and
during
transportation
it
may
be
self-‐firing.
Roughnecks
have
to
use
special
gloves
when
working
with
swarf
due
to
its
sharp
edges.
If
one
can
improve
the
milling
operations
or
implement
better
alternatives
for
removing
casing
it
will
be
beneficial
both
economically
and
for
HSE
considerations.
Alternative
technologies
to
milling
exist;
this
will
be
further
discussed
in
this
thesis.
The
pro
and
cons
with
this
alternative
technology
will
be
discussed,
as
well
as
the
technology
development
within
the
milling
operations.
To
get
the
overall
picture
this
thesis
starts
with
a
description
of
P&A,
and
some
important
terminology
that
it
is
important
to
have
in
place.
Then
the
governing
regulations
from
NORSOK
D010
are
presented
with
respect
to
P&A.
The
newest
revision
of
NORSOK
D010,
rev
4
that
was
published
in
June
2013
is
later
compared
with
the
previous
revision
of
NORSOK
D010,
rev
3.
The
latest
part
is
more
academic
with
some
simulations
in
Matlab.
For
the
simulation
part
an
existing
steady
state
two
phase
model
is
implemented.
This
steady
state
model
is
modified
for
its
intended
use.
The
purpose
with
this
modified
model
is
to
study
the
ECD
effects
during
milling
operations.
Different
parameters
such
as
the
slip
ratio
and
the
mill
rate
will
be
adjusted,
and
the
results
will
be
visualised
in
excel.
Steel
has
a
large
density
and
for
large
concentrations
of
swarf
there
can
be
a
problem
related
to
fracturing
of
the
well.
The
model
(programmed
in
Matlab)
will
be
used
to
study
the
effects
of
different
milling
rates.
The
results
are
discussed
to
see
the
trends.
Beskrivelse
Master's thesis in Petroleum engineering