Environmental Engineering Reference
In-Depth Information
Oil viscosity at downhole well flowing conditions (
ʼ
owf
) can conveniently be
derived using this chart. For example, if the starting points are:
ʳ
o
= 30° API,
T
wf
= 200 °F,
p
b
= 1,700 psia,
p
wf
= 2,700 psia,
R
sb
= 400 cf/B
Then:
1. Enter ordinate at
ʳ
osc
= 30° API
2. Go right to
T
wf
= 200 °F (Point
A
)
3. Go down to
R
sb
= 400 (Point
B
)
4. Go left to answer, locating Point
D
on the way:
ʼ
ob
= 1.0 cp (Point
C
)
5. Since
p
wf
>
p
b
,
ʼ
owf
>
ʼ
ob
. From Point
D
, go down to read: viscosity
increase = 0.07 cp/1,000 psi (Point
E
)
6.
ʼ
owf
=
ʼ
ob
+ ∆
ʼ
(
p
wf
-
p
b
)/1,000 = 1.0 + 0.07(2,700 - 1,700)/1,000 = 1.07 cp
Question #3.15
ʼ
ob
and
ʼ
owf
Given:
ʳ
osc
= 40° API,
T
wf
= 190 °F,
R
sb
= 1,000 cf/B, ∆
p
= 1,000 psi
a. Find
ʼ
ob
= _____ cp
b. Find
ʼ
owf
= _____ cp
Practical Applications
The whole purpose of this section has been to equip the analyst with a practical tool
for actual field cases where decisions must be made regarding tool rating and interpre-
tation techniques. A few examples should serve to guide the user in the analysis of
day-to-day problems. Before planning a production logging survey, the production
history of the well should be examined. Typically, production rates may be quoted as:
900 BFPD
GOR 500 cf/B
Water cut 15 %
The first job is to translate those figures into the three components:
q
wsc
= 900 × 0.15 = 135 BWPD
q
osc
= 900 - 135 = 765 BOPD
q
gsc
= 765 × 500 = 382.5 Mcf/D
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