Page 136 - Open-Hole Log Analysis and Formation Evaluation

to
Ry
the
had
F,
The
took
high.
=
series
length
a
to
system
link
manner.
tortuous
saturated
formation
be
FR,
the
of the
Ro
resistivity
(The
paths
rock
number
as
factor.
of straight
of
determined
increases.
Conversely,
related
that
It
method Archie
the
in
tubular
electrical
simple
by
lines
system,
with a variety ofbrines.
of cores
was
if Ais
Archie
Electrical Formation
this
used
pores
Rj.
He
pore,
water,
a Function
to
some
thus
tubular
large,
&,,
a
of slope
formation
When
Factor
grows
actually
arrive
manner,
and
conducted

of different
the
inverse
at
model
is
F (see
logical
the
factor
take;
larger
this
fig.
many
to
as
step
bears
results
see
power
to
the
referred
could then measure,
resistivity
fig.
6.15).
little
were
porosity and
at
resistivity
to
of
porosity
conclusion
as
in
function.
6.16.)
experiments
propose
of the
a
tortuosity
was
plotted,
in
saturated
The
rock
that
Note
an
he
relationship
of the

to
each
simple.
that
factor
F and
system
the
attempt
100%-water-
Z,
the electrical
pore
predictable
founda
He
each brine salinity,
by
one
is

"
Sp
Sw»
Ry
Se
F
Ina
HH F Fsuch that factor by some formation related to R,, say that Ro is F /¢? or II ), Ro = SRu used formation to ly close we may write porosity itself, to the a and proportional Where Since A is to as Ro. water is referred saturated with tock 100% low. The resistivity ofa the resistivity is apm the the of length Zand conductive path fo
with
=.
=
=
a
FS
related
Was
FIGURE

THE
Archie’s
the
more
to
resistivity,
definition
6.16
its
1
Saturation
Ro/F
Ro,
equal
Ry/R,.
.
R)/R,.
=
the
0.81/¢?
to
PHYSICS
to
and
0.62/¢""°
itself.
Ry
definition
mare
the
the
. OD IO QOROQON oXe § OF
experiments
mis
generalized
Schematic
X
factor
resistivity.
to

He
formation
ees.
resistivity ofa rock sample
form,
of Fand
square
b"/a
(Sands)
usually
showed
formation
ROCK/ELUID
this
|
found
root

factor
porosity
that
arrive
(Carbonates)
close
experimentally
is
of
Ina wet formation we may therefore
at
Eventually Archie
that
to
the
2
the
the
the
resistivity
the
€quation
relations
found
R,,
(Humble formula-soft
(fig.
combine
can
of Tortuous Pore System.
tatio
fatio
if
are:
that
determined
be
Saturation
equation
6.17).
that is:
of the
of a
|
formations)
written
wet
Three
constants.
core
100% saturated with water to the
as:
Ro/R,—that
ais

could
| |
i
fractional water saturation,
formation
be
the Fto@ relationship
usual-
commonly
»
the
laboratory-measured
resistivity

- is, of —~—- OSGQO a