Compatibility Study of Treated Effluent from KNPC

Compatibility Study of Treated Effluent
from KNPC- MAB Refinery
with Brackish Water, PIC Water
and GC’s Formation Water
Imad Al-Maheimid, Ahmad Kh. Al-Jasmi
Research & Technology Group - KOC
Surface Team
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Introduction
 Kuwait oil company extracts brackish
groundwater from the Abdaliyah water field
which is the single source of brackish water
supplying West, SEK Oil Fields and Ahmadi
residence areas.
Maximum Demand of Source Water (based on last year data)
Summer
1. Average source Water required at STF/NTF
= 135,000
2. Average source Water required at WK GCs
= 35,000
3. Average source Water required at Camel Point + Irrigation = 25,000
Total Demand of Source Water at KOC
195,000
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(Unit : BWPD)
Winter
85,000
25,000
10,000
120,000
Normal
105,000
30,000
15,000
150,000
Introduction
 KOC is proposing to increase oil production,
accordingly, the use of ground water will increase,
overexploitation of ground water will lower the
water table in Abdaliyah Brackish field this will
allow the intrusion of the saline water and it my
lead to brackish water deterioration.
 To avoid this phenomenon and to secure KOC low
salinity water future demand, suitability of KNPC,
PIC effluent treated from MAB & MAA Refineries
have been explored to be utilized in KOC for
industrial applications.
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Introduction
 KNPC effluent treated water may will mixed with
Abdaliyah brackish water, this water mixture will
be utilized for desalting wet crude at each of 14
Gathering Centers, GC's desalters which located
downstream of separator. A scaling / precipitation
may occur when the formation waters from each
GC which containing high levels of calcium,
magnesium, strontium and barium are mixed with
wash water with high level of sulphate ion.
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Introduction

In order to establish the suitability of treated effluent from
both sources (KNPC + PIC) for KOC daily operational
activities,
a
comprehensive
compatibility
study
of
the
mentioned treated effluent with KOC brackish water and
formation water from each GC was executed. Also full analysis
of KNPC treated effluent water were conducted to explore the
suitability of this water for irrigation purposes, bacteria
analysis were carried out in order to design the most suitable
bacteria inhibitor (biocide) with its optimal dosing rate to
control bacteria growth within the water distribution system.
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Objectives
 To analyze and characterize the mixing waters
 To perform computer scale compatibility study to
predict type and masses of scale that could be
generated at recommended temperature and
pressure conditions
 To predict scaling tendency and mass of individual
waters at defined temperature and pressure
conditions
 To check compatibility of these waters using
Laboratory Jar Tests
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Deliverables
 Executive summary
 Introduction and background
 Sampling and analysis techniques
 Results of the static and computer scale
prediction
 Interpretation and discussion
 Conclusions and recommendations
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BACKGROUND
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Common Oilfield Scales
Name
Chemical formula
Calcium carbonate (calcite)
CaCO3
Calcium Sulphate
Gypsum
Hemi – Hydrate
Anhydrite
Barium Sulphate
BaSO4
Strontium Sulphate
SrSO4
Iron Compounds
Ferrous Carbonate
Ferrous Sulfide
Ferrous Hydroxide
Ferric Hydroxide
Ferrous Carbonate
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CaSO4.2H2O
CaSO4.1/2 H2O
CaSO4
FeCO3
FeS
Fe(OH)2
Fe(OH)3
Fe2CO3
COMPATIBILITY STUDY
EXPERIMENTS
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Schematic Diagram – Mixing of Water
GC -A
GC -B
ABDALLIYAH
GC -D
GC -E
GC - F
GC -G
Brackish Water
GC -C
GC -H
GC -I
GC -J
SOUTH
TANK FARM
KNPC-MAB
TREATED
EFFLUENT
WATER
GC - K
GC -L
GC -M
GC -N
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PIC TREATED
EFFLUENT
WATER
GC- GATHERING CENTER
KNPC - Kuwait National Petroleum
Company
PIC - Petrochemical Industries Company
Mixing Water in De-salter
 At desalter we’ll have
 Wash Water
 Formation Water
 Crude in contact with
the formation Water
 Gas phase in equilibrium
H2S and CO2
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Mixing Scenarios
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METHODOLOGY
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Methodology
Computer Scale Predictability
 Balancing the ionic composition of water
analysis
 Predicting the self scaling potential of
individual water
 Compatibility of two waters at various temp
and pressure
 Study the worst case mixing scenario
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Methodology
Static Jar Test
 Mixing water samples at various ratios
 Incubation at 65 °C for 72 hours
 Mixture – cool down to room temperature
 Filtration through 0.45 micron membrane
filter
 Weighing filtrate in mg per liter
 SEM / EDS analysis of the membrane
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Methodology
Full Ionic Composition of Water
 Anions
(CO3-2, HCO3-1 SO4-2 ,Cl-1 ,S-2 )
 Cations
(Ca+2,Mg+2,Sr+2,Ba+2,Na+1,K+1,
Fe+2, Fe+3)
 Dissolved gases (O2 and
H2S)
 Specific Gravity
 Total Dissolved Solids
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Analytical Parameters
Physical Parameters of PIC, KNPC and Brackish water.
Parameters
Unit
Brackish
KNPC
PIC
Conductivity
mS/cm
4.64
2.00
0.02
7.63
7.83
5.97
1.0000
0.9980
0.9970
pH
Density
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gm/cm3
Analytical Parameters
Compositional Analysis of PIC, KNPC and Brackish water.
Elements
Unit
Brackish
KNPC
PIC
Sodium
Calcium
Magnesium
Potassium
Strontium
mg/l
mg/l
mg/l
mg/l
mg/l
534
387
146
41
14
551
30
19
32
6
5
2
0.38
1.41
2
Barium
Iron
Lithium
Silicon
Boron
Aluminum
Chloride
Bicarbonate
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
0.02
0.17
0.19
0.11
0.06
8.92
1.20
0.10
872
140.79
0.05
0.01
0.75
0.04
0.00
664
214
0.06
0.002
0.08
0.24
0.00
8
6
Sulfate
Phosphate
Ammonia Nitrogen
Nitrite
Nitrate
mg/l
mg/l
mg/l
mg/l
mg/l
1288
177
1.3
0.05
0.01
0.02
1.1
1.18
3.1
0.7
4.3
0.01
0.8
0.08
0.02
Total
Dissolved Solid
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gm/l
3.43
1.69
0.03
Analytical Parameters
ELEMENTS
Unit
GC- A
GC -B
GC -C
GC -D
Sodium
Calcium
Magnesium
Potassium
Strontium
mg/l
mg/l
mg/l
mg/l
mg/l
51293
10726
2462
3261
295
56670
11892
2684
2780
327
45875
9416
2238
2654
228
43094
9372
2147
2504
283
Barium
mg/l
3.46
3.12
2.04
2.50
Iron
Lithium
Silicon
Boron
Aluminum
Chloride
Bicarbonate
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
5.67
4.17
7.20
32.85
0.04
103971
231.07
4.25
4.44
44.10
4.04
114796
247.42
0.68
3.97
3.65
29.32
0.85
92381
189.59
1.40
4.60
3.30
38.40
0.10
86398
141
Sulfate
Phosphate
Conductivity
pH
Density
Dissolved H2S
mg/l
mg/l
mS/cm
589.1
579.6
411.1
524
gm/cm3
ppm
1.417
144.8
6.46
1.1080
<0.1
1.727
143
6.36
1.1060
<0.1
6.803
170.7
6.38
1.1020
1
2.4
129
6.66
1.0970
<0.1
Total
Dissolved Solid
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mg/l
172882
190053
153433
144513
16.46
Analytical Parameters
ELEMENTS
Unit
GC -E
GC-F
GC -G
GC -H
Sodium
Calcium
Magnesium
Potassium
Strontium
mg/l
mg/l
mg/l
mg/l
mg/l
49169
10343
2480
2950
190
45470
9457
2420
1917
300
47079
9725
2347
2645
293
49505
10450
2278
2416
273
Barium
Iron
Lithium
Silicon
Boron
Aluminum
Chloride
Bicarbonate
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
1.70
2.30
2.10
3.22
0.80
4.31
4.60
25.80
0.00
98455
247
4.20
7.53
5.00
35.20
0.10
99111
249
2.30
7.01
7.20
35.30
0.10
94383
259
1.66
3.66
5.41
40.09
0.10
100044
305.24
Sulfate
Phosphate
Conductivity
pH
Density
Dissolved H2S
Total
Dissolved Solid
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mg/l
mg/l
mS/cm
537
211
523
769.1
0.35
103
6.40
1.1060
1.5
164408
1.06
133
6
1.1010
1
159189
2.15
143
6
1.1080
<0.1
157308
0.008
178.7
6.35
1.1100
<0.1
166094
gm/cm3
ppm
mg/l
FINAL CONCLUSION &
RECOMMENDATION
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Conclusion
 All waters were found to be self scaling except
PIC water.
PIC acts as a diluent for all mixing calculations.
GC waters showed comparatively higher scaling
tendency than wash waters.
In most of the mixing cases, total scale mass
increases with increasing GCs formation water.
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Conclusion
 Scale predicted are:
calcite, barite, anhydrite, celestine.
Barite (BaSO4)
 Celestine (SrSO4)
Calcite (CaCO3)
Worst Case Combination:
20% KNPC and 80% GC formation water
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Recommendation
Scale Inhibitor
Application of suitable scale inhibitor will be
possibly best scale controlling method.
Chemical should be compatible with other
chemicals used and with the waters.
Laboratory trial is necessary for selection of
most suitable chemical.
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Recommendation
PIC water can be used as diluent for minimizing
scaling mass.
 Worst case combinations should be avoided.
Dissolved gases like H2S and O2 should be
removed completely.
 Scaling occurring at STF (if any) should not
carry over to the desalter.
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Recommendation
Scaling at STF should be removed either by using
filtration unit or by giving enough retention time to
the solids in the settling tank.
pH and temperature control will be another
operational approach to control scaling tendency.
 It is also advisable to monitor scale deposits
regularly at the expected locations.
 Exact composition of solid deposit should be
identified by SEM /EDS / XRD methods.
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Scale Inhibitor Screening & Assessment.
The conclusions drawn from the study are as follows:
 Jar test did not show sufficient content of scale formation, even
for uninhibited brine. Hence it was not possible to evaluate the
performance of chemicals and optimize their dosage level
 Initial tube blocking test was conducted at 105 F and 15 psi
pressure which did not show any scale precipitation. Hence
additional tests were conducted at elevated temp of 160 F to
increase the quantity of scale formation which would plug the
test coil.
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Scale Inhibitor Screening & Assessment.
 Uninhibited brine at elevated temp of 160 F showed significant
scale precipitation, plugging the test coil within 6 hours. Also
differential pressure increased to about 600 psi while all the
four chemicals did not show plugging of test coil over a 20 hour
continuous flowing period and differential pressure did not
exceed 0.5 psi under the same temp and pressure conditions
which clearly indicates need for suitable scale inhibitor.
 All the scale inhibitors with a concentration as low as 2 ppm
were successful in the prevention of scale formation during the
tests.
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Scale Inhibitor Screening & Assessment.
Recommendation
 Since all the inhibitors, are successful in preventing scale
deposit, it is recommended that the final selection of scale
inhibitor should be based on cost and availability of chemicals.
 Scale inhibitor should be dosed at 5 ppm in the initial stage.
Later, it can be reduced to 2 ppm on plant stabilization if the
results are favorable in the prevention of scale formation.
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Suitability of KNPC Treated Effluent Water for
Irrigation Purposes
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Suitability of KNPC Treated Effluent Water for
Irrigation Purposes, Cont.
KNPC Effluent Treated Water Specifications are within KEPA Appendix – 15 but it is recommended not to use
this water for crops irrigations.
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KNPC Treated Effluent Water Microbiology Analysis
Parameter
Samples Results
Units
Method used
Heterotrophic Plate Counts (HPC)
2000
Mpn/1ml
MPN
Total Coliform Bacteria (TC)
3500
Mpn/100ml
MPN
E.Coli Bacteria
<1
Mpn/100ml
MPN
Fecal Coliform Bacteria (FC)
14
Cfu/100ml
MF
Enterococci Bacteria
13.4
Mpn/100ml
MPN
Salmonella Bacteria
6
Cfu/100ml
MF
Streptococci Bacteria
4
Cfu/100ml
MF
Sulphate Reducing Bacteria (SRB)
P
P/A
Injection
Nitrate Reducing Bacteria (SRB)
P
P/A
Injection
MPN; Most Probable Number, MF; Membrane Filtration, Cfu; Colony Forming Unit,
P/A; Presence/Absence
The existing bacteria can be controlled and inhibited by chlorine dioxide or any available biocide, biocide
screening is needed to select the most suitable one with its optimal dosing rate.
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Acknowledge
KISR PRC.
KISR WRC.
KNPC.
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THANKS
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