United States
Environmental Protection
Agency
Municipal Environmental Researc
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-209 Oct. 1981
Project Summary
Oil Content in Produced
Brine on Ten Louisiana
Production Platforms
George F. Jackson, Eugene Humes, Michael J. Wade, and Milton Kirsch
A survey of the oil content of brine
effluents from offshore crude oil
production platforms was conducted
to determine (1) the amount of oil in
the brine, (2) the factors affecting the
oil content of the brine, and (3)
approaches for reducing the oil content
of brine.
Ten-day surveys were conducted on
10 platforms representing a wide
range of characteristics with respect
to produced fluids, processing sys-
tems, and water treatment systems.
Each platform had a flotation unit for
final oil separation before discharge.
At least 40 gravimetric and 20
infrared tests for oil were run on brine
effluents from each platform. Tests
for oil were also run at upstream
points in the systems. Other brine
tests were run for correlation with
effluent oil content, including soluble
oil, oil drop-size distribution, sus-
pended solids, surface tension, ionic
analysis, pH, specific gravity, and
temperature. Crude oil tests included
specific gravity, surface tension,
boiling point distribution, and temper-
ature.
Records were kept of operational
factors, including water cuts, lift
methods, pressures, chemical addi-
tion programs, and hydraulic loading
of water-treating units.
Test and operational data were
analyzed for correlation with effluent
oil content.
This Project Summary was developed
by EPA's Municipal Environmental
Research Laboratory, Cincinnati, OH.
to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
This study was conducted to develop
information on the oil content of brine
discharges from offshore oil platforms.
The specific objectives were:
1. To characterize the brines dis-
charged from offshore platforms
with respect to oil content,
2. To identify the factors contributing
to the oil content of the brine, and
3. To consider approaches to reduce
brine effluent oil content.
The program was conducted in two
phases so that Phase I experience could
be used to revise the Phase II plan. The
approach to meeting the program
objectives was to conduct 10-day field
surveys on 10 platformsthree during
Phase I and seven during Phase II. A
major part of the testing was directed to
defining the variability of brine effluent
oil content. Special tests were run to
determine whether the oil in the brine
was soluble, dispersed in fine droplets,
or associated with suspended solids.
Information on the design and operation
of the water treatment systems were
also recorded for correlation with brine
oil test data.
Methods and Materials
Platform Selection
The objective in platform selection
was to pick platforms representing a
-------
wide spectrum of factors having the
most influence on effluent oil content.
The following technical criteria were
used for platform selection:
Treatability
Lift method
Water cut
Process complexity
Chemical addition
Gravity separator type
Flotation unit type
Flotation unit hydraulic loading
All platforms selected were producing
oil, gas, and water. The number of wells
producing oil per platform varied from 1
to 30 at the time of the survey. Three
types of gravity separator and flotation
units with five different design variations
were included in the survey. The range
of hydraulic loading of flotation units
selected was 9% to 84% of design
rating. The percent of production gas
lifted ranged from 0% to 99.8%. No two
chemical addition programs were the
same. A generalized schematic of an
offshore production system is shown in
Figure 1.
All of the platforms considered for the
survey were in the Louisiana Gulf Coast
area from Lafayette (South Marsh
Island) to east of the Mississippi delta,
and from the marsh out to 140 km
offshore. The platforms studied were
located where the large hydrocarbon
accumulations were mostly associated
with salt domes or anticlines overlying
various salt masses.
The characteristics of produced fluids
from other locations and other forma-
tions may be different from those
included in this survey. Little information
is generally available on the amounts of
soluble oil and surface active compounds
present in the brine from various
locations and formations. But differences
are known to exist that could have a
significant effect on oil/water separa-
tion.
Data Collection
Analytical Test Methods
Standard analytical test methods
were used for most of the testing
program. Procedures published by the
U.S. Environmental Protection Agency
(EPA), American Society for Testing and
Materials, American Public Health
Association, American Petroleum Insti-
tute, and special procedures adapted for
this program were used. Table 1 lists
parameters measured and methods
used. Each method is summarized in the
following paragraphs.
Table 1. Analytical Test Methods
Parameters
Method
Oil and Grease
Temperature
pH
Boiling range distribution
Specific gravity
Water cut
Suspended solids
Surface tension
Viscosity
Crude oil solubility
Susceptibility to separation
Ionic analyses of
sodium, potassium
Iron, calcium, magnesium,
barium
Chloride, sulfate
Total dissolved solids
Sulfide
Alkalinity
Bacterial culture
Particle size distribution
Infrared (EPA' Storet 00560)
Gravimetric (EPA')
Thermometer fASTM2)
Combination electrode fASTM3 Method B)
Gas chromatography (ASTM2 022887-73)
Hydrometer (ASTM2 D1298-67)
Volumetric (ASTM2 DJ 796-68)
Gravimetric (EPA' Storet No. 00530
ASTM3 D1888-67)
Surface tensiometer (ASTM3 D 1590-60)
Viscometer (ASTM2 D 445-74)
Silica gel adsorption (APHA4 502E)
Equilibration (Shell Oil Company)6
Filtered brine (Mobil Oil Corp.)1
IR scan (EPA')
Infrared (Conoco, Inc.6 API5 734-53)
Flame emission (API5)
Atomic absorption (EPA1) (API5)
Autoanalyzer (APHA4)
Gravimetric (EPA')
lodometric titration (APHA4)
Electrometric titration (API5)
Sulfate reducing (API5 RP 38)
Photomicrographic (Rockwell International8) (
1. U.S. Environmental Protection Agency, 1979, "Methods for Chemical Analysis of
Water and Wastes."
2. American Society for Testing and Materials, "1974 Annual Book of ASTM
Standards, Part 23/24, Petroleum Products and Lubricants."
3. American Society for Testing and Materials, "1978 Annual Book of ASTM
Standards, Part 31. Water."
4. American Public Health Association, "Standard Methods for the Examination of
Water and Wastewater," 14th Edition. 1975.
5. American Petroleum Institute, 1968, "API Recommended Practice for Analysis of
Oilfield Water."
Nonstandard method.
6.
Oil and Grease Determination
Total recoverable oil and grease deter-
minations by infrared (IR) analysis were
made on board the platforms according
to EPA procedures. Samples of brine
were also extracted for analysis of total
recoverable oil and grease by gravimetric
techniques.
IP-Oil w/Silica Gel Test- TheIR-
oil w/silica gel test was used as an
indicator of polar water-soluble-type
compounds in the brine. Hydrocarbon
oils in Freon have been shown to be
adsorbed on silica gel only to a very
limited extent, whereas naphthenic
acids, vegetable oils, and other polar
compounds with significant water
solubility are adsorbed. To the extent
that the IR-oil w/silica gel test is a true
indicator of solubility, it is also an
indicator of a lower level of treatability
by physical processes. The IR-oil and
corresponding IR-oil w/silica gel tests
were run on the same Freon extracts.
The term "soluble oil" is used in this
report to indicate the material extracted
by silica gel. The term "dispersed oil" is
used for the unextracted material.
Measurements to determine adsorb-
able hydrocarbons were made according
to APHA Standard Method 502E.
IP-Oil Filtered Brine Test The
IR-oil filtered brine test was also used as
an indication of treatability. Brine
-------
I Chemicals I
[
i VI
Subsurface
0/G
W/S
Gas
Oil
Water
Separator
Storage]
Tank \ Oil
to Pipeline
O
W
IPrecipitator)
(0/W Separator)
(Skim Tank)
W
0
Polishing Unit
Flotation,
Coalescer, etc.
Water to Sea
S
Chemicals
Arrows show direction of fluid flow.
Letters alongside arrows indicate materials present in that stream.
Letters are arranged in order of decreasing concentration of each componente.g.,
0/G/W Code: OilGasWater.
Figure 1. Generalized schematic of offshore production system.
filtered and the IR-oil content of the
filtrate was measured. Only soluble oil
and very fine droplets (less than 8
micrometers) were expected to pass
through the filter.
Susceptibility-to-Separation Tests
The purpose of the susceptibility-to-
separation tests was to provide a
quantitative measure of the rate of
separation of oil from brine by gravity.
The tests were run by a procedure
supplied by Conoco, Inc.* Several
samples were taken, each in a different
separatory funnel. The brine oil content
was then measured after various
defined settling times. For Phase I
testing, the settling times were 1, 5,15,
'Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use
30, 60, and 120 min. For Phase II
testing, the settling times were 2, 5,15,
30, 60, and 120 min. Zero-settling-time
control samples were taken immediately
before and after the settling test
samples were taken. Oil content was
determined by the IR technique previ-
ously described.
Suspended Solids Tests Oil-
coated solids are potential contributors
to brine oil content. Suspended solids
tests were run to check for correlation
between brine suspended soilids and oil
content.
Suspended solids data were generated
following the EPA Storet Method No.
00530. Samples were collected onboard
the platforms using in-line filter holders
to prevent oxidative production of
suspended solids. Each filter was
washed with deionized water, frozen,
and sent to the onshore laboratory for
analysis.
Crude Oil Equilibration Equili-
bration tests were run by a procedure
supplied by Shell Oil Company. A layer
of crude oil was placed on top of a layer
of synthetic brine in a flask so that the
two layers were not mixed. The flask
was then held in an oven at 82°C for 14
days, and a sample of the brine was
taken for an IR-oil content measurement.
For Phase I tests, a synthetic brine
equivalent to a concentration of 100,000
mg/l was used with an oil/water
volume ratio of 4:1. For Phase II testing,
the brine concentration was the same
as that of the produced brine of the
particular platform. In addition, one
equilibration test was run with the same
-------
oil/water ratio as the produced fluids,
and a second test was run with the 4:1
oil/water ratio.
Particle-Size Distribution Small
oil drops are more difficult to separate
from brine than large drops. The
particle-size test provided a measure of
the size distribution of oil drops (in the 2-
to 120-micrometer range) in a given
volume of brine. The drop size measure-
ments were also used to calculate the
concentration of dispersed oil.
Particle-size distribution tests were
run by a new nonstandard procedure
developed by Rockwell International.
Brine samples were taken from a
flowing stream into a cell where the
flow was stopped just long enough to
take photomicrographs of the particles
present. The procedure can distinguish
between solids, oil droplets, and gas
bubbles.
Other Various other chemical and
physical properties were measured on
the brine to investigate possible correla-
tions with oil content values. These
properties included temperature, pH,
alkalinity, specific gravity, surface
tension, viscosity, sulfate-reducing
bacteria counts, total dissolved solids,
and chemical species such as iron,
sodium, potassium, calcium, barium,
chloride, and magnesium.
Operational Characteristics
In addition to analytical testing, the
program plan included collection of
available information on produced
fluids and on the design and operation
of production facilities to evaluate for
correlation with brine oil content. The
characteristics of produced fluids,
chemical usage, design and operating
conditions of the processing system,
upsets, and intermittent operational
procedures were of special interest.
A list of the types of information
recorded is as follows:
Well Data
Formation identification
Total vertical depth
Production rates
Water cut
Lift method
Lift gas
Shut in bottom hole pressure
Flowing tubing pressure
Choke size
Gravity of oil
Receiving vessel
Chemical injection
Processing Data
Flow rate
Temperature
Pressure Vessel parameters
Residence time
Overflow rate
Chemical addition
Upsets
Intermittent operational or maintenance
procedures
Unplanned events
Information on the above factors was
obtained by observations and measure-
ments by the field survey team, from
company records, and by verbal reports
from operating personnel.
Results
Summary of Analytical Test
Results
A summary of the tests for brine
effluent oil content for all 10 platforms
is presented in Table 2. Means and
standard deviations are listed for
gravimetric oil (GR-oil), IR-oil, soluble
oil, and dispersed oil.
Performances of flotation units are
compared in terms of dispersed oil in the
effluent in Table 3. The table also lists
influent oil content, hydraulic loading,
chemical addition rate, and the flotation
unit description for each platform.
A comparison of the performance of
gravity separators is presented in Table
4. The table also lists the type of
separator, settling test results, the
brine/oil specific gravity difference, and
brine temperature.
Drop size distribution tests are
summarized in Tables 5, 6, and 7 for
flotation unit influents and effluents.
The tables include listings of median
drop sizes, largest drop sizes, cumulative
number distributions, cumulative con-
centration distributions in percent, and
cumulative concentration distributions
in milligrams per liter.
Produced fluid properties are described
in Table 8.
Discussion
Effluent Oil Content
Significant differences occurred in
the flotation effluent mean IR-oil, GR-
oil, dispersed oil, and soluble oil
contents of the 10 platforms (see Table
2). Significant negative correlations
exist between effluent IR-oil content
and surface tension sample-to-sample
for each platform. A summary listing of
mean surface tension and linear regres-
sion slope and correlation coefficient is
presented in Table 9 for all platforms.
Flotation Unit Performance
Significant differences exist in the
amount of dispersed oil remaining in the
10 flotation effluents (see Table 2). Four
factors of potential significance to
flotation unit performance are influent
oil concentration, hydraulic loading,
flotation chemical addition rate, and the
type of flotation unit. Significant design
and operational differences exist for all
platforms. A single predominant factor
that determines flotation effectiveness
in removing dispersed oil has not been
identified by simple bivariate data
analysis, and it is therefore not possible
to make quantitative conclusions about
the factors most important to flotation
unit performance. General conclusions
are presented concerning flotation unit
performance, however.
High influent oil content excursions
over 500 mg/l usually had a marked
effect on effluent oil content. An
influent oil content below 300 mg/l
appears desirable. Some lightly loaded
units may handle more than this.
Hydraulic loading was not evaluated
comprehensively during the study
because most units operated at relatively
low and uniform loadings, and problems
were experienced in flow monitoring.
Oil content usually increased when
chemical feed was interrupted.
Gravity Separator Performance
The principal purposes of the gravity
separators in the water-handling systems
are (1) to remove a large percentage of
the oil from the water upstream of the
flotation units, and (2) to protect the
flotation units from the effects of slugs
of oil that might enter the water
handling systems as a result of upsets in
the production-processing systems.
This survey has demonstrated that the
gravity separators do adequately per-
form their primary functions; the
superiority of one type over the others
was not demonstrated, however.
A general relationship exists between
the oil content of gravity separator
effluent and the rate of oil separation as
indicated by settling tests (Table 10).
Brine Soluble Oil
Four tests were used as indicators or
measurements of soluble oil: the IR-oil
w/silica gel test, the equilibration test,
the filtered brine test, and the IR-scan
-------
Table 2. Comparison of Oil Contents of Platform Flotation Effluents
GR-OH. mg/l IR-Oil, mg/l "Dispersed" oil, mg/l "Soluble" oil, mg/l
"Soluble" oil.
Fraction of IR-Oil
Platform
SS107
SS198G
BDCCF5
ST131
BM2C
SMI SOB
EI18CF
WD45C
ST177
SP65B
Z
7.6
18
26
12
22
48
52
63
64
77
(s)
(5.2)
(9.2)
(6.9)
(13)
(6.7)
(16)
(24)
(95)
(74)
(73)
X
15
36
36
37
39
48
76
81
95
106
(s)
(3.7)
(7.8)
(8.3)
(19)
(4.2)
(16)
(38)
(109)
(103)
(99)
X
1.6
5.7
26
5.9
4.9
23
63
66
92
38
(s)
(1.5)
(7.7)
(8.6)
(13)
(5.1)
(13)
(30)
(106)
(126)
(80)
X
13
31
10
28
36
25
13
30
21
61
(s)
(2.7)
(2.7)
(2.3)
(3.1)
(4.1)
(4.7)
(13)
(32)
(13)
(15)
%
87
86
28
76
92
52
17
37
22
58
Note: Some numbers do not check because of rounding. Two significant figures have been retained in all numbers below 100.
x = Mean
(s} - Standard deviation
Table 3. Performance Comparisons for Platform Flotation Units
Flotation effluent
Flotation influent
Platform
SS107
BM2C
SS198G
ST131
SM130B
BDCCF5
SP65B
EI18CF
WD45C
ST177
uispcr
X
mg/l
1.6
4.9
5.7
5.9
23
26
38
63
66
92
SttU Oil
(s)
mg/l
(1.5)
(5.1)
(7.7)
(13)
(13)
(8.6)
(80)
(30)
(106)
(126)
toiai
X
mg/l
215
158
130
386
156
113
170
222
1169
432
r in -on
(s)
mg/l
(49)
(65)
(39)
(199)
(105)
(15)
(147)
(210)
(3409)
(394)
Hydraulic
loading
% of design
24-31
18-39
<1-2.5
3-12
1-20
53"'
II"1
24-30
68-75
26-47
Flotation chemicai
addition rate
ppmv
14
17
255
126
0
5
17
0
7
26
1
Flotation unit
description
4
4
3
4
4
1
4
1
1
4
- cell (M)
- cell (M)
- cell (H)
- cell (M)
- cell (M)
- cell (H)
- cell (M)
- cell (D)
- cell (H)
- cell (H)
Note: (M) = Mechanical gas dispersion
(H) - Hydraulic gas dispersion
(D) = Dissolved gas
(1) Estimated mean.
test (which was only performed during
Phase I).
The API gravity, brine total dissolved
solids, and pH were also examined for
correlation with soluble oil. These
parameters did not show a significant
relationship to soluble oil by simple
bivariate analysis. The filtered brine test
requires additional development to
establish it as a reliable indicator of
soluble materials or treatability.
The equilibration test provides an
indication of soluble components in
brine of the same order of magnitude as
the IR-oil w/silica gel test. The number
of tests is too limited, however, for
definitive conclusions.
When the program plan was devel-
oped, water cut was proposed as a
parameter to examine for correlation
with soluble oil, the theory being that
brine from new wells with a low
water/oil ratio would be high in soluble
oil components. The data indicate that a
significant correlation does exist. Linear
regression analysis yields:
Soluble oil, rng/l = 40 - 0.29 (water cut, %)
r = -0.67
Significant correlations between
suspended solids and brine oil content
were not identified, possibly because of
precision and accuracy problems with
the suspended solids analysis.
The sulfate-reducing bacteria counts
in brine effluents were 100/ml or less
for all platforms except ST131. For this
particular survey, sulfate-reducing
bacteria did not appear to relate to
effluent oil content.
Conclusions
1. The program was successful in
developing an internally consistent
data base of oil content and related
properties for effluent and influent
samples taken on a regular sched-
ule from 10 separate offshore
platforms for 10 consecutive days.
2. The second objective, to deter-
mine the factors affecting the
variability of brine oil content, was
partly satisfied. Simple statistical
analysis identified soluble oil as a
significant variable from platform
to platform, and brine surface
tension as a significant variable on
any platform. Variations in oper-
ating conditions (such as influent
oil content, excursions in influent
oil content, interruption of flotation
-------
Table 4. Performance Comparisons for Platform Gravity Separators
Settling tests Rl
Water Effluent Settling time Sample"' Hydraulic loading A
rine/oil
specific
treatment IH-OII. mg/l K min 17nmin point Tank rpl gravtty
separator
Platform type x (s) mg/l mg/l - (m3/d)/ (m3/d)/
m2 plate pack
BDCCF5 Skim Tank 113 (15) 103 53 9-i 27
SS198G CPI 130 (39) 209 117 8-i - 10
SM130B CPI 156 (105) 169 107 8K-i - 242
BM2C CPI 158 (65) 219 128 8-i - 580
SP65B Skim Tank 170 (147) 311 128 5A30 21
SS107 None 215 (49) 119 86 9-i 120
EI18CF Skim Tank 222 (210) 151 39 8-i 84
ST131 Gun Barrel 386 (199) 851 239 8-i 8.2
ST177 Gun Barrel 432 (394) 210 100 9-i 31
WD45C None'3' 1169 (3409) 59 54 9-i 38
(1) Separator influents were sampled if a sample tap was available. Other points and effluents were
samples could not be taken.
(2) Gravity separation was in an oil tr eater with the primary function of separating water from oil.
(3) Gravity separation was in two gun barrels with the primary function of separating water from oil.
-
.232
.258
.268
.262
.221
.270
.330
.287
.309
.183
sampled
Brine
temperature
°C
41.1
36.5
40.9
45.6
38.0
49.2
39.9
22.8
36.6
40.2
when influent
Table 5. Cumulative Percent-by-Number Drop Size Distribution for Composites of Test Runs
Oil Percent-by-number of drops with diameter equal or less than
Platform pies
Large Largest
Sam- Number Calculated11' Measured31 2 um 5pm JO /jm 20 um 30 um 40um 60 um 100 urn >100um drops drop
pies''" of drops mg/l mg/l % % % % % % % % % >40 >60 u
Flotation Influent
WD45C
ST177
BM2C
ST131
BDCCF5
SS107
SSI98G
EI18CF
SM130B
399
340
410
359
410
378
365
574
1.715
2.557
32
1.537
29
1,109
492
1.231
53
277
9
293
11
108
284
685
42
204
99
51
189
88
44.5
130
0.01
3.8
0.01
3.8
63
6.2
942
855
325
41.0
32.8
540
45.0
64.0
99.6
98.0
89.0
92.5
89.0
97.0
85.6
93.8
9997
99.5
973
994
972
99.87
973
9865
100.OO
99.92 9997 100.00
99.0 100.OO
99.88 99.98 100.00 -
0 0
3 0
0 0
1 0
25
55
35
49
99.0 100 OO 0 0 35
700.00 0 0 28
990 9955 99.95 100.00 11 2 97
9905 995 99.77 99.94 100.00 41 26 120
Flotation effluent
WD45C
ST177
BM2C
ST131
BDCCF5
SS107
SS198G
EI18CF
SM130B
254
512
410
157
368
410
115
355
293
1.637
1,586
26
14
565
26
48
629
372
407">
35
4
7
57
4
26
161
50
9
5
28
1
3
78
15
57
57
9
001
25.2
0.01
40
5.6
30.3
95.2
97.1
18
32.5
87.8
150
64.0
48.0
94.2
98.2
99.63
91
85.0
98.8
93.5
94.8
860
99.78
99.4
99.94
1OO.OO
100.00
9985
100.00
99.42
9845
99 78
99.8
9998
99.94
99.42
999
9978
99.95
99.98
99.98
700.00
1OO.OO
9978
9995
100 OO
99.98
700.00
700.00 -
700.00
8
1
O
0
1
0
0
0
3
1
0
0
0
1
0
0
0
0
64
41
17
16
81
14
35
32
59
'"Number of brine samples photographed for drop counts.
I2'O// as calculated from drop counts
'^Dispersed oil as measured by IR-Oil w/Silica Gel tests on the brine effluent from the particle-size test equipment when the particle-size-distnbution test was run.
141 Test run during upset conditions.
chemical, and hydraulic loading)
produced notable changes in
effluent brine oil content; but no
simple statistical correlations
were developed.
3. A comparison of the oil content of
the gravity separator effluent with
the 5- to 120-min values of the
susceptibility-to-separation test
indicated that the equipment was
generally operating near those
values. A comparison of flotation
influent and effluent oil showed
that the flotation units reduced the
oil content below the limit for
gravity separators indicated by the
susceptibility-to-separation test.
Most flotation units were effective
in removing dispersed oil, but their
removal efficiencies differed.
Special adaptations of six test
methods contributed to the suc-
cessful accomplishment of the
project objectives.
a. The infrared method for mea-
suring oil concentrations in
brine proved to be acceptable
for onsite determinations. Al-
though it gives different results
from the gravimetric method,
the two can be correlated on a
platform-by-platform basis.
-------
Table 6. Cumulative OH Content by Drop Size in Percent
Oil Percent of oil in drops with diameters equal or less than '
Platform
Sam-
ples12'
Number Calculated" Measured3' 2 um
of drops mg/l mg/l %
Sum
%
^
20 um
30 urn
40 um
%
60 um 100 um
% %
Large
>700 um drops
% >40
>60
Largest
drop
u
Flotation Influent
WD45C
ST177
BM2C
ST131
BDCCF5
SS107
SS198G
EI18CF
SM130B
399
340
410
359
410
378
365
574
1.715
2,557
32
1,537
29
1,109
492
1,231
53
277
9
293
11
108
284
685
42
204
99
51
189
88
5
0.42
0.01
003
0.01
006
0.02
002
44.5
17.5
30
60
30
145
1 9
1 7
76
375
27.5
428
260
708
108
68
925
60
46.0
762
430
930
31 0
124
100 00
79
570
90.0
652
100.00
43.0
155
91
100.00
970
100.00
56.0
228
100.00
70000
79.5 700.00
37 0 65 5
0
3
0
1
0
0
77
70000 47
0
0
0
0
0
0
2
26
25
55
35
49
35
28
97
120
Flotation Effluent
WD45C
ST177
BM2C
ST131
BDCCF5
SS107
SS198G
EI18CF
SM130B
254
512
410
157
368
410
115
355
293
1,637
1.586
26
14
565
26
48
629
372
407""
35
4
7
57
4
26
161
50
9
5
28
1
3
78
15
1.3
73
012
001
0.85
0.01
0.07
0.04
1 1
66
37
20
30
17.4
2.8
11 4
42
17.5
115
55
670
48.5
375
800
31 0
275
24.8
27.2
70
100.00
100.00
463
10000
47.0
71 0
260
488
80
51 5
470
978
26.0
740
87
580
1OOOO
1OOOO
26.0
943 70000
70000
580 70000
70000
S
7
0
0
7
0
0
- 0
3
7
0
0
0
7
0
0
0
0
64
41
17
16
81
14
35
32
59
'"Oil as calculated from drop counts in milligrams per liter
"'Number of brine samples photographed for drop counts.
^'Dispersed oil as measured by IFI-Oil w/Si/ica Gel tests on the brine effluent from the particle-size test equipment when the particle-size-d/stribution test was run.
"'Test run during upset conditions
Table 7. Cumulative Assigned Oil Content Distribution by Drop Size Groups in Composites of Test Runsn}
Oil Assigned concentration of oil in drops w/dia equal or less than '"
Sam-
P/atform pies
Flotation Influent
WD45C 399
ST177 340
BM2C 410
ST131 359
BDCCF5 -
SS107 410
SS198G 378
EI18CF 365
SM130B 574
Flotation Effluent
WD45C 254
ST177 512
BM2C 410
ST131 157
BDCCF5 368
SS707 470
S5798G 775
EI18CF 355
SM130B 293
Number Calculated'3'
of drops mg/l
1,715
2,557
32
1,537
29
7.709
492
7,237
7,637
7,586
26
74
565
26
48
629
372
53
277
9
293
77
708
284
685
40715'
35
4
7
57
4
26
767
50
Measured"' 2 um
mg/l mg/l
42
204
99
57
789
88
9
5
28
7
3
78
75
00
0 7
0.0
0.0
00
00
00
0.0
0.2
0.0
0.0
0.0
0.2
5 um
mg/l
73
722
30
7.4
36
7.5
0.2
0.2
4.9
0.0
03
33
2.6
70 um
mg/l
77 6
873
257
36.7
20.4
6.0
6.0
2.4
70.5
0.8
0.9
27.5
3.7
20 um
mg/l
793
755.4
426
47.4
586
70.9
9.0
5.0
730
7 0
7 4
554
39
30 um
mg/l
239
783.6
645
57.0
87 3
73.6
74.4
7.4
76.3
3.9
40 um
mg/l
420
797.9
99.0
705.8
20.7
76.2
30
78.0
3.9
60 um 100 um
mg/l mg/l
2040
750.3 7890
32.6 57.6
76.2 28 0
75.0
Large
>100um drops
mg/l >40
0
3
0
1
0
0
77
88.0 47
- 8
7
0
0
7
0
0
0
3
>60
0
0
0
0
0
0
2
26
7
0
0
0
7
0
0
0
0
Largest
drop
f
25
55
35
49
35
29
97
720
64
47
77
76
87
74
35
32
59
"'The cumulative oil concentration data in this table were calculated by multiplying the total analytically determined dispersed oil concentration by the percentage
concentration data reported in Table 200 in full report
"'Number of brine samples photographed for drop counts.
"'Oil as calculated from drop counts
"'Dispersed oil as measured by IR-Oil w/S/lica Gel tests on the brine effluent from the particle-size test equipment when the particle-size-distnbution test was run
Test run during upset condition
b. The silica gel/IR method for oil
and grease analysis provided a
measure of the soluble oil
content. The soluble oil content
at the discharge conditions is a
lower limit of treatability by gas
flotation.
c. The equilibration method mea-
sured brine soluble components
of the crude oils. Results using
this method are of the same
order of magnitude as those
obtained by the silica gel/IR
method.
The susceptibility-to-separation
test proved to be a useful semi-
quantitative tool in estimating
the ease and ultimate limit of
gravity separation.
The filtered brine method was
intended to provide a measure
-------
Table 8. Properties of Produced Fluids
Platform
Water Cut, Percent
Brine Properties
pH
Total Dissolved So/ids, mg/l (Gravimetric)
Temperature, °C
Specific Gravity"'
Surface Tension,"' dynes/ cm
Crude Oil Properties
API Gravity @ 156°C
Temperature, °C
Specific Gravity" '
Surface Tension,"' dynes/cm
Viscosity @ 37.8°C, Cent/poise
Boiling flange, °C
Initial Boiling Point
Final Boiling Point
SP65B
35
69
105,000
386
1.086
67
29.5
36.0
0865
30
824
150
480
WD45C
64
70
80.500
397
1.073
60
258
36.9
0890
30
20.21
150
485
ST177
47
63
203,000
36.1
1 151
67
36.8
329
0842
30
347
150
480
BM2C
27
66
1 14,000
450
1 093
60
34.2
39.1
0831
25
3.41
150
410
ST131
32
63
138,000
22.6
1 129
61
367
200
0842
25
285
150
480
BDCCF5
91
67
108,000
409
1 095
61
31.4
31 8
0863
28
826
150
480
SSI 07
87
66
112.OOO
48.2
1.095
63
35.2
44 5
0825
26
3.71
150
500
SS198G
10
7 1
114,000
31 1
1.106
66
340
30.2
0.848
27
524
150
500
EI18CF
90
63
162.00O
382
1 140
57
41 9
35.1
0810
26
2.44
150
480
SM130E
19
62
163.000
40.1
1 133
68
29.2
350
0865
26
692
150
400
Percent recovered
Below - 200
200 - 250
250 - 300
300 - 350
350 - 400
400 - 450
450 - 500
500 - 550
49 1
104
14.6
14.5
5 1
54
08
0.2
297
124
21.9
21 2
62
68
1 4
0.4
428
10.5
193
130
66
6.9
0.8
0.2
61 1
22.6
132
24
06
0 1
00
00
61 7
226
88
1 6
0.3
0 1
00
00
459
245
22.5
56
13
02
00
00
38.2
24.3
25.5
6.3
3.0
20
0 7
00
484
272
175
3.2
1 6
1 2
06
00
37.1
23.4
273
7.5
2.1
03
0.0
00
77.4
14.0
70
1.4
02
0.0
00
00
Note: Brine properties are based on tests on flotation unit effluents. Crude oil properties are based on tests on crude oil samples taken after all treatment steps o
the platform
"'Specific gravity and surface tension test results are reported for approximately the listed temperature
Table 9. Surface Tension Summary
Platform
SP65B
WD45C
ST177
BM2C
ST131
BDCCF5
SSI 07
SS198G
EI18CF
SM130B
Mean
surface
tension
67
60
67
60
61
61
63
66
57
68
Linear
Slope
-6.9
-17.8
-11.6
-0.4
-1.24
-2.94
-6.1
-4.5
-3.2
-3.0
regression
Correlation
coefficient
-0.96
-0.87
-0.70
-0.5
-0.65
-0.73
-0.92
-0.68
-0.84
-0.32
of soluble oil plus finely dis-
persed (less than 10 micro-
meters) oil in the effluent. As
such, this method could provide
an alternative to the silica
gel/IR method in establishing a
lower limit of treatability for
flotation processes. Differences
in experimental procedure
caused this method to be in-
consistent with the IR method
for determining oil and grease
in some cases.
f. Oil drop-size distributions were
obtained with unique new
8
equipment from photomicro-
graphs for both flotation unit
influents and effluents. These
measurements determined the
size range of dispersed oil
droplets removed by gas flota-
tion. Dispersed oil concentra-
tions calculated from these
distributions compared poorly
with measured IR oil concen-
trations.
The experience of this project indicates
that the first four methods can be used
to characterize produced brine. The
filtered brine method, after suitable
modification, appears promising. Th
photomicrographic method isapplicabl
to verifying mathematical models and i
improving equipment design.
Recommendations
1. A comprehensive analysis of th
data base provided for this projec
must be undertaken. Included shoul
be a multivariant analysis of th
treatment processes to identify th
significant variables affecting th
stabilization of oil in water an
process unit performance. No othe
field studies of treatment processe
should be undertaken until this wor
is complete and its recommendation
are known.
2. Methods for characterizing oil ii
water beyond simply measuring c
its concentration should be investi
gated. Some obvious candidates ar
(1) boiling point distribution curve
for gas/liquid chromatography (GLC
(2) gas/liquidmass spectrometr
(GLC/MS), and (3) infrared spectres
copy. Those methods that provi
useful could be employed in a stud
of the characteristics of bulk oils am
extracts from a range of wate
discharge points.
3. Two methods subject to problem
during the present study (filter
-------
Table 10. Comparison of Settling Tests for Separator Effluent
Platform
BDCCF5
SS198G
SM130B
BM2C
SP65B
SS107
EI18CF
ST131
ST177
WD45C
Water
treatment
separator
type
Skim
Tank
CPI
CPI
CPI
Skim
Tank
None
Skim
Tank
Gun
Barrel
Gun
Barrel
None
Mean
mg/l
113
130
156
158
170
215
222
386
432
1.169
Proportion in settling"'
Test range
Percent
85
90
80
66
60
8
60
95
31
0
Settling test range"'
IR-oil content
5 min
mg/l
121
237
192
261
331
136
163
1,259
271
68
120 min
mg/l
43
101
100
105
113
56
38
168
85
49
l"The settling test range is reported as the highest 5-minute settling test result and the lowest 120-minute test result.
^Gravity separation was in an oil treater with the primary function of separating water from oil.
{3]Gravity separation was in two gun barrels with the primary funciton of separating water from oil.
brine oil in water and flow rate) need
more study. A search should be
conducted for a reliable, portable,
continuous flowrate meter.
The full report was submitted in
partial fulfillment of Contract No. 68-
03-2648 by Rockwell International
under sponsorship of the U.S. Environ-
mental Protection Agency.
-------
George F. Jackson and Eugene Hume are with Crest Engineering, Inc.. Tulsa, OK
74101; Michael J. Wade is with Texas Instruments. Inc., Dallas. TX 75165;
and Michael Kirsch is with Rockwell International Corporation. NewburyPark,
CA 91320.
John S. Farlow is the EPA Project Officer (see below).
The complete report, entitled "Oil Content in Produced Brine on Ten Louisiana
Production Platforms," (Order No. PB 82-1O8 408; Cost: $33.50. subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Oil and Hazardous Materials Spills Branch
Municipal Environmental Research LaboratoryCincinnati
U S. Environmental Protection Agency
Edison. NJ 08837
10
. S. GOVERNMENT PRINTING OFFICE: I98I/559-092/3337
-------
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