Page 182 - Open-Hole Log Analysis and Formation Evaluation

This
Footal
shows
SP
=
referred
potential
measured
the
distinguish
Ey
to
can
t+
+
as
be
(see
may
the
total
En,
the
. components: two potential membrane a so-called SP. 9.4 LiquidJunction FIGURE |=} V// Current — + —$+ Zone - ; -— a _ + — 9.3 Liquid-Junction Effects. FIGURE Original cry Solution Solution Concentrated OPEN-HOLE LOGGING Ll, 108
SP
=
Conditions
later

liquid
include
SP.
measured
Invaded
in
yet
under
picture.
Ea
It
the
junction
Fe]
electrochemical
another
and
“Factors
(Z,,)
should
is
borehole
. “eee: Current 0 Fa] -=—=] ee MEASUREMENTS
CC. +}- +3- + = Mud. : Filtrate ae Conditions Dynamic flow Net current
.
be
by an
Affecting
component,
Shale Y
noted
created
components
the
of
the
that
(see
+3-
Sand

fe
the
electrode.
fig.
SP”),
ON Ne ——
SP.

9.5).
membrane potentials they
:
Figure
and
the potential

When
are

to
electrokinetic
9.6
The

Ye
Water
Connate

fe FIGURE 9.

Original
in
R,,
the

Ryp

than
are

in
Rp
>
equal.

figure
R,),
9.7,
the
=
find
deflects
fresh
to
: vis a safe guess that somewhere in the region of 7000 ft Ry,pancl water that is fresher than the mud filtrate so that. 2, is greater thari formation water. In sand C, the SP is reversed, indicating formation sand B, the SP deflection is less than in sand A, indicating a fresher Ry Ci.e., formation water is saltier than the mud filtrate). In the well but is reversed n
SP.
called
the
a
water
liquid
Dynamic
left
in
When
LMU),
reverse
(the
the
SP.
to
SP
junction
the
:
Other
left
Conditions
eens
salinities
potential
deep
is