Page 50 - Open-Hole Log Analysis and Formation Evaluation

‘ Hot-Wire Gas Detector ppm. as percent, ppk, or mud log may be quoted _on the the in to standardized and (i.e., in terms of volume/volume) -volumetric units universal total SPWLA modern reading. The a of All three types Katharometer. or a detector, detector, a flame-ionization a hot-wire ““~either is made
Tf,
25
will
X
on
atoms
passes
1
centage
the
can
This
=
position.
the
then
Detector
assure
Calibration
circuit.
heated
heated
of mud
carbons
carbons
a
flow
CCD.
For
electrical
to
25%
sufficient
be.a
of
(higher
through
other
of each
a
device
Katharometer
to
are
C
Such
any
the
a
EMA
through which
Flame-lonization
gas
flowed
chamber senses
platinum
hand,
through
is
of
constant
or cuttings
a
ionize
example,
function
Calibration
A high-temperature
The principle of the
mud
past
resistance,
the
responds
if
device
gas
of
wire.
norm
it
(Thermal
the
flow
numbers)
these
or
detector
“equivalent
a
to
terms of equivalent methane
temperature
in
It
Detector
of
can
a
encountered,
is
weighted
both
mixture
(see
the
which
hot-wire
then
air
that
ionized
be

hydrogen
and the
by
passes
the
in
(FID)
hydrocarbon gas, when present,
the
of
less
cuttings
(Catalytic
mixture
the
methane
total-gas
its
and
gas:
mixture
the presence the
gas
C
flame
gas
of
thermal
turn
heat
assures
Conductivity
in air (EMA).
heats
hydrocarbons.
is

:
is
containing
mud
is
of
detectors
air,”
with
through
carrier gas
accurately
sensitive
1983)
response
or
is
detectors
the
air.
A pair
number.
the

gases
Combustion
to
*
than
(air),
will
Detector,
output can be continuously recorded as total gas
EMA.
The
For
as
conductivity
circulated.
combustion
produce
the wire and
with
maintained
concentration
be:
methane
or. cuttings
monitored
on
should
ions by the small
calibrated.
report
either
in
TCD)
detector is simple. A wire
a
detector,
hydrogen
by
be
Thus,
the

and
gas,
and
of the
more
a
Detector,
When
the
of any
The response of the
of electrodes
its
“total
the
example:
and
in
75%
combustion
made
thus raises
FID
flame
gas
CCD)
mud log.
Regulators
per-
carbon
current that
the
its
bridge
gas”
units
hydro-
in
is
the
chamber
resistor is
hydro-
measured bya
air
com-
device
of
or
mixture
in

To
Gas
(fig.
Gas
C4
is
is
2.2).
also
determine
Gas
related
the
Ethane
to
Different
combined
passed through
Iso-butane
the
to
Chromatography
length
C3Hs
CaHio
obtain

drilling
composition
mechanical
components
of hole
of
4
2
of the
a
details
process.
the
raw
gas,
acolumn packed with
a
gas
an
readings
normalized
/ independent of the of the drilling the raw total gas reading to give These are a “dilution ratio” that is 25% Bit size Volume of mud/unit Penetration rate Mud-pump output variables These include: It common to correct the much ethane, a third as much propane, etc. Thus, the same total gas reading could be obtained with Totals 25% C5 Pentane CsHi2 1 5xX
mixture
for
a
take
»
Electrodes
chromatograph
6X2=12
reading
only
Charge
61%
process.
is
inert powdered
i. qT
Recorded
number
;
that
multiplied
as
Chromatogram
and
EMA:
halfas
is
used.
of
by
solid
different