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 platforms—three 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

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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

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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 component—e.g.,
  0/G/W Code: Oil—Gas—Water.

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

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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

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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

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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/liquid—mass 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 Laboratory—Cincinnati
        U S.  Environmental Protection Agency
        Edison. NJ 08837
                               10
                                                       . S. GOVERNMENT PRINTING OFFICE: I98I/559-092/3337

-------
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-------