Page 109 - Open-Hole Log Analysis and Formation Evaluation

94
or
I.
log
log
log.
not
Also
able
than
cause
recall
in
mud
noted
excess
accept
made.
ditions
well. As
should
Many
Washed
making
Variable
OVERALL
course,
more
ask:
section
of some
technical
One
establish;
on
If
or
is
is
Although
question:
sections,
that
that
poor
sequently,
worthless.
boreholes,
a
that
examined
out
sometimes
Adefinite
none;
tool
to
METHODS
such
malfunction.
the
opposite
it
so,
measurement
REPEATABILITY.
“Is
times
Acceptance
circumstances.
a
“Can
the
are
each
is
the
OF
logging
conclusive,
rerun
eccentralization,
nature,
the
an
quality
large
any
reliable
usually
outweigh
the
SP
importance of the
holes,
repeats
to perform an
section.
a
TECHNICAL
it
bad
a functional
sticking
log
routinely
carefully
of
Other
Aside
conductivities
and
within
heading
was
For the most serious
zone
Properly
on
cost
log.
decisions.
centering,
log
After
speed,
situation
run,
must
method
would
tools,
written
of
of about
from
anomaly
include:
their
imperative
possibility ofa malfunction.
all,
QUALITY.
in the
GATHERING
indications
The
will
logging
be
percentage
be
and
may
for
errors,
every
it
particularly
possible
200
formation
check ofthe
be
interpretation
that
over
determine whether
ft.
everyone who will
log
originally
error. When the
data.
a
of interest.
of all
Many
deviated
may
logging
to
rerun
functioning
unfair
criterion for acceptance
particularly
those
the
Standards for Logs
should
an
of formation'resistivity.
be
run.
capability,
rerunning
to
of correct
in
causes
“remarks”
logs
The
of
instructions
following
equipment
be
These
influence
log
FORMATION
things
use this
alteration.
wells,
the
logged
accept
will
before
accurate?”
of
somewhat
tool
equipment,
accurate interpretation?”
be
determination
large
most
or
might
resistivity
when
engineer’s
anomaly
log
may
intimate
If in
Ifin
records
failures,
valid
poor
poor
required
nearly
significant.
log is not rerun,
extremely
rerun.
interval
holes
reject
guidelines
important
that
It
are
tools,
that
different.
of a bad
log see the
the
contain
errors,
obvious
might
operation
is
doubt,
data
doubt,
the
all
The
will
run
factors
deciding
with
always
log
is
except
adversely
and
is
Good
tool
should
in
EVALUATION DATA
are:
such
rerun
rerun
that
conclusions
to
valuable,
noncircular
fairly
decisions.
interfered
under
repeat
suggest
affect
centralization
the
erroneous
outweigh
Often a log can be corrected visually or matherhatically,
ask
whether
assist
interesting
logs
can
problem,
should
high
could
cross
unusual
con-
This should be resolved by repeating the
with
the
very
to
a repeat section of 200 ft
rotation,
equipment
the
or
rugose
judgment
in
to
questionable
the log.
Con-
or rejection ofa log is difficult to
error and/or be
the
log.
the
be
error should be
column andalso noted on the
it is a mistake to thinka bad log is better
though
but
be
are
data
of

95
for
5.
the
are
Salt
can
can
The
read
used
either
DEPTH
Sulfur
a
Casing
TABLE
OFFSET
should
greater
be
several
The
logging
to
positive
the
followed
absolute
by
more
ABSOLUTE
Casing
sections,
5.3
Anhydrite
dissipate
company’s
especially
a
geological
Benchmark
different
usually
read
Comparing
particularly
LOGS.
than
WIRELINE
phenomena
not
cable
can
of the
obtaining
check
LOG
presence
measurements.
penetrate
same
true
If
an
most
values
with
in
the
too,
block,
log
in
about
of the
properly
is
up
the
122.0
every
This
more
56.0
50.0
67.0
glamorous
Sonic
crosscheck
MEASUREMENTS.
an
repeatability
altogether
= (us/ft)
56
is
calibrated
basic
VALUES.
such
zeto-porosity minerals
some
deeper,
accurate
run
100
Tool Response
will
shales
of
well
sometimes
casing.
that of new
as
ft.
very troublesome;
of metallic
one
a
in
with
recognizable.
us/ft
is
or
seldom
available
shallow
should
readings.
for many days after the well
be
such
types
In
with
common
in
in
sheave
is
The
fish
_
but
log
be
depth
as
the
2.98
a
2.04
2.02
function,
The
a
unfamiliar
migrate
almost
or
parameters.
casing
in
other
(g/cc)
used
offset
varying
These
Density
run
LOGGING OPERATIONS
but
reading
Measurement
Comparison
from
Common
either
tools,
as
by
used.
the
area.
possible,
halite,
a
down
in
of
logs
the
of
diameter
control
passage
one
may
owing
always
changes
case,
but
Expected Value
run
Absolute
natural
are
is
vertically,
—
to
of
invasion
be
~3.0
-1.0
of equipment
-2.0
log
table
developing
that
devices,
check.
the
impervious
of the places where
magnetic
borehole
Neutron
it
occur
result
depth-is.
when
5.3.
All
Benchmarks
anhydrite,
unbonded casing.
likely
Formations
time.
may
Limestone
field,
it
indicated
viewpoint
rather
(which
in
or
to
%
diameters measured bya four-arm caliper should be
rocks.
for Various
profiles.
Compensated
is
affected
tends to
drillpipe
only
that
marks
or
The
can
readings
be
benchmarks
perhaps
logged. Though unusual,
may
accumulate
caliper
in
in
by
of log
depth control
get
operational
be
Tools
a
—
as
equal.
are
is
continue
log
5.05
4.65
wear.
5.43
(P,)
the
the
with
rigorous
consist
usually
|
placed
accurate
lost
tools
Factor
to
limestone
useful.
Invading
appear
The
on
done,
quality,
is advisable to be
listed,
and
can
annuli,
This
Photoelectric
on
procedure
the
depth
among
provided
if
logging
for
be
slightly
of pure,
this
The sonic
should
two
consistent
is
known
invaded
quite
they
filtrate
response,
change
such changes

time-related

or .