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Chemical Process Sensitivity Analysis Example
Stabilization of Crude Oil
Created by:Nugroho Wibisono (Weby)
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17 December 2012
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Reference
This example is taken from Oilfield Processing Volume Two: Crude
Oil, Manning, Francis; Thompson, Richard E.; PennWell Publishing,
1995 (ISBN: 0-87814-354-8) Chapter 9: Stabilization and Sweetening
of Crude Oil
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Fluid Info
Liquid Vol. Flow. (Barrel/day)
Molar Flow (MMSCFD)Mole%
Component Name
120oFTemperature
228.180.870.000N2
22.450.060.000CO2
15,278.4637.920.000Methane
4,008.026.310.000Ethane
3,224.654.930.805Propane
1,053.861.3638.691i-Butane
2,870.123.8329.427n-Butane
1,8022.0713.135i-Pentane
2,354.132.738.415n-Pentane
4,698.004.807.211n-Hexane
12,131.7811.161.915248F
10,712.038.000.336340F
10,727.436.840.0031413F
10,719.506.090.001472F
42,893.9115.030.00000657F
12298 lbmol/hour
650 psig
Flow rate
Pressure
Hydrocarbon Gas ProductDominated by methane component as sales
gasLiquid Hydrocarbon ProductRVP < 12 psiaLiquid is stored in
near atmospheric tank
336195170141110Mol Wt.
220295350370442Pc, psia
975807750673573Tc, oF
0.8870.8350.8170.7930.762SG 60/60
657472413340248NBP oF
657F472F413F340F248FBoiling Point Cut
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Overall Schematic of the PlantFeed stage pressure
(650 psig)
Stock Tank Pressure
(5 psig)
First Stage
Pressure
Second Stage
Pressure
Hydrocarbon Liquid Processing System Hydrocarbon Gas Processing
System
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We will discuss only in the hydrocarbon liquid processing
system.
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Multistage Separation System
What is the optimum first stage pressure and second
stagepressure to obtain maximum liquid product?
Separator-4
Separator-3
Separator-2
Separator-1Feed
Liquid Product
CV-1
CV-2
CV-3
Gas Product
Gas Product
Gas Product
Gas Product
Feed stage pressure
(650 psig)
Stock Tank Pressure
(5 psig)
First Stage
Pressure
Second Stage
Pressure
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Sensitivity Analysis using Process Simulator (Aspen Hysys)
Software: Aspen Hysys Use Databook feature to understand the
effect of various combination of
first stage pressure and second stage pressure to the oil
recovery rate
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Sensitivity Analysis Simple Steps
Run 3 (three) Case Studies in Aspen Hysys Databook First case
study
1st stage pressure = 120 psig 2nd stage pressure = 10 30 psig
with 1 psig increment
Second case study 1st stage pressure = 140 psig 2nd stage
pressure = 10 30 psig with 1 psig increment
Third case study 1st stage pressure = 160 psig 2nd stage
pressure = 10 30 psig with 1 psig increment
Copy the simulated data to MS Excel
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Sensitivity Analysis ResultOptimum Oil Recovery
96,850
96,900
96,950
97,000
97,050
10 15 20 25 30
Second Stage Pressure (Psig)
O
i
l
P
r
o
d
u
c
t
i
o
n
(
B
B
L
S
/
D
a
y
)
First stage pressure = 120 psig
First stage pressure = 140 psig
First stage pressure = 160 psig
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Some thoughts
The recovery rate of the crude oil is different if we operate
the plant differently
There are certain optimum operating condition for different
first stage and second stage pressure
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Different Topology of Separation Stage
What is the product different if we have different topology of
the plant?
First topology Second topology Third topology
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Sensitivity Analysis Simple Steps Run 3 (three) Case Studies in
Aspen Hysys Databook First case study
Feed pressure = 650 psig The pressure outlet from CV1 = 5
psig
Second case study Feed pressure = 650 psig 1st stage pressure =
120 psig The pressure outlet from CV2 = 5 psig
Third case study Feed pressure = 650 psig 1st stage pressure =
120 psig 2nd stage pressure = 30 psig The pressure outlet from CV3
= 5 psig
Copy the simulated data to MS Excel
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Sensitivity Analysis Result
Dependence of Oil Recovery on Number of Stages
94
95
95
96
96
97
97
98
98
1 2 3
No. of Stages
O
i
l
R
e
c
o
v
e
r
y
,
B
P
D
(
x
1
0
0
0
)
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Some thoughts
The recovery rate of the crude oil is different if we have
different stage of separations
We may not increase the stage of separation as the recovery rate
is not directly proportional to the stage addition consider CAPEX
to the crude oil gain
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Other Form of Sensitivity Analysis
Combination of 1ststage pressure and 2nd stage pressure to the
oil recovery rate
Useful to map the operating condition for production
operations
O
i
l
R
e
c
o
v
e
r
y
R
a
t
e
Top view
First stage pressure (psig)
S
e
c
o
n
d
s
t
a
g
e
p
r
e
s
s
u
r
e
(
p
s
i
g
)
First stage pressure (psig)
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And Many Other Examples
Thanks
