U.S. patent application number 10/719567 was filed with the patent office on 2004-06-17 for removal of water solubilized organics.
Invention is credited to Hart, Paul R..
Application Number | 20040112828 10/719567 |
Document ID | / |
Family ID | 26677891 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040112828 |
Kind Code |
A1 |
Hart, Paul R. |
June 17, 2004 |
Removal of water solubilized organics
Abstract
Methods and compositions for removing organics solubilized in a
water-like fluid (WSO), such as the water produced in connection
with the production of hydrocarbons from subterranean formations,
are described. Hydrophilic .alpha.-hydroxy-monocarboxylic acids
(AHAs), such as hydroxyacetic (glycolic) acid, alone or optionally
together with anionic polymers, have been found to be effective.
The compositions and methods of this invention have reduced
corrosion and scale formation problems as compared with other
methods employing stronger acids to remove WSO. The AHAs have
pK.sub.a's of greater than 3.8.
Inventors: |
Hart, Paul R.; (Sugar Land,
TX) |
Correspondence
Address: |
PAUL S MADAN
MADAN, MOSSMAN & SRIRAM, PC
2603 AUGUSTA, SUITE 700
HOUSTON
TX
77057-1130
US
|
Family ID: |
26677891 |
Appl. No.: |
10/719567 |
Filed: |
November 21, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10719567 |
Nov 21, 2003 |
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10008173 |
Nov 13, 2001 |
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6695968 |
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60322249 |
Sep 10, 2001 |
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Current U.S.
Class: |
210/502.1 ;
210/638; 252/364 |
Current CPC
Class: |
C02F 1/56 20130101; Y10S
210/908 20130101; C02F 2101/30 20130101; C02F 1/26 20130101; C02F
2103/06 20130101; C02F 2303/08 20130101; C02F 5/00 20130101; C02F
2101/32 20130101 |
Class at
Publication: |
210/502.1 ;
210/638; 252/364 |
International
Class: |
B01D 015/04 |
Claims
I claim:
1. A composition for removing solubilized organics from a
water-like fluid phase consisting essentially of: a hydrophilic
a-hydroxymonocarboxylic acid (AHA); and an anionic polymer.
2. The composition of claim 1 where the AHA has a pK.sub.a of
greater than 3.8.
3. The composition of claim 1 where the AHA has the structure
RR'C(OH)COOH where R and R' are independently selected from the
group consisting of hydrogen and nonacidic hydrocarbonaceous
groups, with the proviso that
n.sup.H+0.5(n.sup.C)-7(n.sup.O)<15(n.sup.OH) where n.sup.H=the
total number of hydrogens on carbons, n.sup.C=the total number of
carbons, n.sup.O=the total number of oxygens not attached to
hydrogens, and n.sup.OH=the total number of --OH groups in the
molecule.
4. The composition of claim 1 where the anionic polymer is selected
from the group consisting of poly(acrylic acid) and
poly(methacrylic acid) and salts thereof, poly(acroyl sulfonic
acid) and poly(vinyl sulfonic acid) and salts thereof, and
copolymers of the aforementioned polymers with acrylic amides and
esters, and mixtures thereof.
5. The composition of claim 1 where the anionic polymer has a
degree of polymerization of above 30.
6. The composition of claim 1 where the anionic polymer has a
degree of polymerization between about 3000 and about 300,000.
7. The composition of claim 1 where the anionic polymer is selected
from the group consisting of poly(acrylic acid) and
poly(methacrylic acid) and salts thereof, poly(acroyl sulfonic
acid) and poly(vinyl sulfonic acid) and salts thereof, and
copolymers of the aforementioned polymers with acrylic amides and
esters, and mixtures thereof.
8. The composition of claim 1 where the weight ratio of AHA to
anionic polymer in the composition ranges from about 1:1 to about
10,000 to 1.
9. The composition of claim 1 where the weight ratio of AHA to
anionic polymer in the composition ranges from over 50:1 to about
10,000 to 1.
10. A composition for removing solubilized organics from a
water-like fluid phase comprising: a hydrophilic
.alpha.-hydroxymonocarboxylic acid (AHA) having a degree of
polymerization of above 30; and an anionic polymer, where the
weight ratio of AHA to anionic polymer in the composition ranges
from over 50:1 to about 10,000 to 1.
11. The composition of claim 10 where the AHA has a pK.sub.a of
greater than 3.8.
12. The composition of claim 10 where the AHA has the structure
RR'C(OH)COOH where R and R' are independently selected from the
group consisting of hydrogen and nonacidic hydrocarbonaceous
groups, with the proviso that
n.sup.H+0.5(n.sup.C)-7(n.sup.O)<15(n.sup.OH) where n.sup.H=the
total number of hydrogens on carbons, n.sup.C=the total number of
carbons, n.sup.O=the total number of oxygens not attached to
hydrogens, and n.sup.OH=the total number of -OH groups in the
molecule.
13. The composition of claim 10 where the anionic polymer is
selected from the group consisting of poly(acrylic acid) and
poly(methacrylic acid) and salts thereof, poly(acroyl sulfonic
acid) and poly(vinyl sulfonic acid) and salts thereof, and
copolymers of the aforementioned polymers with acrylic amides and
esters, and mixtures thereof.
14. The composition of claim 10 where the anionic polymer has a
degree of polymerization between about 3000 and about 300,000.
15. A composition comprising: a water-like fluid phase; at least
one solubilized organic in the water-like fluid phase; an anionic
polymer; and a hydrophilic .alpha.-hydroxymonocarboxylic acid
(AHA), where the weight ratio of AHA to anionic polymer in the
composition ranges from over 50:1 to about 10,000 to 1.
16. The composition of claim 15 where the AHA has a pK.sub.a of
greater than 3.8.
17. The composition of claim 15 where the AHA has the structure
RR'C(OH)COOH where R and R' are independently selected from the
group consisting of hydrogen and nonacidic hydrocarbonaceous
groups, with the proviso that
n.sup.H+0.5(n.sup.C)-7(n.sup.O)<15(n.sup.OH) where n.sup.H=the
total number of hydrogens on carbons, n.sup.C=the total number of
carbons, n.sup.O=the total number of oxygens not attached to
hydrogens, and n.sup.OH=the total number of --OH groups in the
molecule.
18. The composition of claim 15 where the anionic polymer is
selected from the group consisting of poly(acrylic acid) and
poly(methacrylic acid) and salts thereof, poly(acroyl sulfonic
acid) and poly(vinyl sulfonic acid) and salts thereof, and
copolymers of the aforementioned polymers with acrylic amides and
esters, and mixtures thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 10/008,173 filed Nov. 13, 2001, now
allowed.
FIELD OF THE INVENTION
[0002] The present invention relates to methods and compositions
for removing solubilized organic material from water-like fluids,
and more particularly relates, in one embodiment, to methods for
removing solubilized organic material from water-like liquid phases
using compositions having no or low corrosivity, volatility, or
scaling potential.
BACKGROUND OF THE INVENTION
[0003] The production of petroleum hydrocarbons from underground
formations usually produces varying amounts of formation or connate
water. The production ratio of "produced water" as it is often
called, to petroleum hydrocarbons usually increases over the
lifetime of a well. It is not uncommon that oil well production
fluids are composed of 90% or more of water and only 10% or less of
crude oil. Produced oilfield water contains a diverse mixture of
compounds that varies from formation to formation. Of particular
importance is the "oil and grease" (O&G), a conventional
pollutant defined in the Clean Water Act and codified at 40 CFR
401.16. O&G comprises those compounds which extract into a
non-polar solvent, such as 1,1,2-trichlorotrifluoroethane (Freon
113) or n-Hexane, from water at a pH less than 2 (cf.
EPA-600/4-79-020, Methods 413.1 and 413.2). The term "water
solubilized organics" (WSO) has been used to describe a group of
these components which are not so extractable when the extract is
subsequently treated with silica gel (cf. EPA-821-B-94-004b, Method
1664). These silica adsorbing compounds largely comprise carboxylic
acids, which naturally occur in crude oil, whose conjugate bases
partition to some significant extent to the produced water at the
system pH but which partition to some significant extent as acids
to the extraction solvent at the more acidic extraction pH. Thus,
under system conditions, they are dissolved, rather than dispersed,
in the produced water.
[0004] The discharge of WSO has never been desirable. While their
concentration may be relatively small, up to 1,000 ppm, they
nevertheless give rise to environmental problems when the aqueous
phase is discharged into the environment without their removal.
These compounds are included in the discharge limits for O&G
mandated by Congress in the Clean Water Act. In order to meet those
ever more stringent limits, a process to reduce the level of
dissolved or usolubilized" organics in the discharged water streams
is needed. As discharge limits become more stringent, the need for
WSO removal is expected to increase. Furthermore, the water
solubilized organics are valuable substances to recover in the
produced oil.
[0005] One of the first steps after removal of the oil well
production fluid is to separate the oil from the water by phase
separation techniques. Separation is conventionally accomplished
using a bulk separator or a free water knock out system. Virtually
all of the hydrocarbon is conveniently recovered in this manner.
However, such traditional oil-water separation methods do not
remove these WSO compounds from produced water.
[0006] Conventional water clarifiers predominantly remove dispersed
or "in-soluble" (not solubilized) oil and generally remove very
little, if any, WSO. Cationic polymers might remove the 10-20% of
the WSO associated with microemulsions in the produced water, where
such emulsions exist.
[0007] Over the past several years, many other methods have been
utilized to remove WSO from produced water. A variety of filtration
and adsorbent media, including ceramics and activated charcoals,
reverse osmosis membranes, ion exchange resins, bacterial
degradation or other biological treatment, oxidation, distillation,
and acidification have all been tried with various degrees of
success.
[0008] One common, cost-effective method of treatment utilizes
mineral acids to lower the pH of the produced water and force the
WSO components into the crude oil. Acidification and extraction of
the WSO into the crude is simple, cost-effective, and requires very
little additional equipment. The mechanism is simple: 1) the
more-water-partitioning organic anion salts are converted to the
more-oil-partitioning organic acids with protonation by the
stronger mineral acid and 2) these more oil partitioning organic
acids are extracted into the crude. However, there are significant
disadvantages to this method, including, but not limited to, the
hazards of handling mineral acid, corrosion problems in storage and
processing equipment, scaling of the processing equipment, and
reduced effectiveness of conventional water clarifiers.
[0009] None of the materials in prior use have proven satisfactory.
Hydrohalide and hydrocarboxy acids (HX, H.sub.2(CO.sub.2).sub.x)
are volatile enough to harm human health and downstream
distillation processes. Monoprotic oxy acids (HNO.sub.x,
HClO.sub.x) have dangerous oxidation potentials. Nonvolatile,
multiprotic oxy acids (H.sub.xSO.sub.x, H.sub.xPO.sub.x) are less
harmful and less dangerous, but have the additional disadvantage of
forming insoluble scale deposits on the production equipment.
Nonacidic and cationic compounds have proven unreliable or
incompatible with existing water clarifier treatments.
[0010] U.S. Pat. No. 5,395,536 discloses a process for removing
carboxylic acids from aqueous solutions using a composition of a
polyaluminum chlorohydrate and a cationic polyelectrolyte. After or
during the initial contact of the aqueous solution with the
composition, an organic liquid may optionally be added after which
separation into an aqueous phase and an organic phase occurs
whereby the organic acids are removed in the organic phases. The
preferred polyaluminum chlorohydrate is aluminum chlorohydrate, and
the preferred cationic polyelectrolyte is a high molecular weight
poly(dimethyl diallyl) ammonium chloride.
[0011] Another method for removing organics, such as water soluble
organics (WSO) from fluids containing water, such as oil process
water is described in U.S. Pat. No. 6,159,379 that involves
contacting the fluid with an effective amount of an organic
ammonium salt. No added acid is necessary, although in some
embodiments, weak acids such as glycolic acid, can be used to give
synergistic improvement in organic removal. Suitable organic
ammonium salts have the formula: R.sup.1R.sup.2R.sup.3N.-
sup.+HX.sup.-, where R.sup.1 is a saturated or unsaturated alkyl
group or an aryl group, or saturated or unsaturated alkyl group or
an aryl group substituted with a heteroatom selected from the group
consisting of N, O, S, P and halogen; R.sup.2 and R.sup.3 are
independently H or a saturated or unsaturated alkyl group or an
aryl group, or saturated or unsaturated alkyl group or an aryl
group substituted with a heteroatom selected from the group
consisting of N, O, S, P and halogen; and X is a halogen atom or an
anion of a protic acid.
[0012] It would be desirable if a simple, economical procedure for
removing WSO compounds from water without the disadvantages of
using strongly acidic materials could be devised.
SUMMARY OF THE INVENTION
[0013] Accordingly, it is an object of the present invention to
provide a composition and method for removing WSO from produced
water that does not require the use of strong acids.
[0014] It is another object of the present invention to provide a
method and composition for removing WSO from produced water that
does not create scaling problems and that is compatible with
conventional water clarifier treatments.
[0015] In carrying out these and other objects of the invention,
there is provided, in one form, a method for removing water
solubilized organics (WSO) from a water-like fluid phase involving
contacting the water-like fluid phase with an effective amount of a
hydrophilic a-hydroxymonocarboxylic acid (AHA) and separating at
least one WSO from the water.
[0016] There is provided in another non-limiting embodiment form of
the invention a composition for removing solubilized organics from
a water-like fluid phase where the only components capable of
affecting the removal of solubilized organics from a water-like
fluid phase are a hydrophilic .alpha.-hydroxymonocarboxylic acid
(AHA) and an anionic polymer.
[0017] In an alternate, non-limiting embodiment of the invention
there is provided composition for removing solubilized organics
from a water-like fluid phase that includes a hydrophilic
.alpha.-hydroxymonocarboxylic acid (AHA) having a degree of
polymerization of above 30 and an anionic polymer. The weight ratio
of AHA to anionic polymer in the composition ranges from about 50:1
to about 10,000 to 1.
[0018] In yet another non-limiting embodiment of the invention
there is provided composition that includes a water-like fluid
phase, at least one solubilized organic in the fluid phase, an
anionic polymer, and a hydrophilic .alpha.-hydroxymono-carboxylic
acid (AHA), where the weight ratio of AHA to anionic polymer in the
composition ranges from about 50:1 to about 10,000 to 1.
BRIEF DESCRIPTION OF THE DRAWING
[0019] The FIGURE is a chart of the molar efficiency of various
compounds at removing WSO over the indicated dosage ranges.
DETAILED DESCRIPTION OF THE INVENTION
[0020] When water is produced from underground formations along
with petroleum it contains numerous impurities. One type of
impurity is called oil and grease (O&G). This includes, by
definition, compounds that will extract into n-hexane or Freon 1 13
(1,1,2-trichlorotrifluoroethane) from water acidified to pH <2.
The discharge limit for O&G is typically 29 ppm, averaged over
a year. (Excursions are tolerated but must be compensated for.) The
purpose of this invention is the reduction of the O&G in the
discharged water to this limit.
[0021] The present invention involves the use of hydrophilic
.alpha.-hydroxymonocarboxylic acids (AHAs), alone or in combination
with anionic polymers, to reduce the total oil and grease
(O&G). It is applicable to water produced from underground
formations with pH greater than about 4, containing solubilized
organic compounds that are in contact with any amount of free or
emulsified oil. The term "water-like fluid phase" includes the
produced water described, and also includes, but is not necessarily
limited to, a water-free glycol extraction such as would occur in
the oilfield, a gas plant, or petrochemical plant. The term
generally would include mixtures of water and an oil-like phase,
but would not include water-in-oil emulsions.
[0022] The water solubilized organic (WSO) compounds in O&G are
those that partition at least partly to water in their native state
but partition at least partly to oil (or at least Freon) in their
acidified state. Such co- or bi-partitioning compounds are more
polar than straight hydrocarbon oil and adsorb onto silica gel from
the Freon extract. The portion of the O&G removed by silica gel
is reported as the WSO. This includes compounds, such as butanol or
benzene, which partition to some extent both ways regardless of the
pH, and those, like organic acids, which partition more to water at
the native pH than at the test pH. This last group of compounds is
reduced by adding hydrophilic a-hydroxymonocarboxylic acids (AHAs).
The first group of emulsified compounds is reduced by adding the
anionic polymers in conjunction with the AHAs. If the anionic
polymers are not added, the decrease in WSO resulting from the
addition of the AHA can be accompanied by a corresponding increase
in the emulsified oil, for no net decrease in the O&G.
[0023] Unlike the current art using mineral acids, the hydrophilic
AHAs are weak organic acids, with pKa's of greater than 3.8, having
the structure: RR'C(OH)COOH, where R and/or R' can be hydrogen or
any nonacidic hydrocarbonaceous group provided that the total
number of H's on C's plus 1/2 the number of C's minus 7 times any
O's not attached to H's is less than 15 per OH group (including the
.alpha.-OH). Otherwise, it is insufficiently hydrophilic to stay in
the water. The hydrophilic condition of the AHA, RR'C(OH)COOH, may
also be expressed as follows, where:
[0024] R and R' are independently selected from the group
consisting of hydrogen and nonacidic hydrocarbonaceous groups,
[0025] with the proviso that
n.sup.H+0.5(n.sup.C)-7(n.sup.O)<15(n.sup.OH)
[0026] where
[0027] n.sup.H=the total number of hydrogens on carbons,
[0028] n.sup.C=the total number of carbons,
[0029] n.sup.O=the total number of oxygens not attached to
hydrogens, and
[0030] n.sup.OH=the total number of --OH groups on molecule (i.e.
including the .alpha.-OH)
[0031] One preferred hydrophilic AHA is hydroxyacetic (glycolic)
acid (R and R'=H). This is also expected to be the least expensive
one. Other suitable AHAs that meet the above definition include,
but are not necessarily limited to: .alpha.-hydroxyheptanoic acid
(R.dbd.C.sub.5H.sub.11, R'.dbd.H),
.alpha.,.beta.-dihydroxytridecanoic acid, and polypropylene glycol
glycidyl acid (R.dbd.HO[C.sub.3H.sub.6O].s- ub.nCH.sub.2,
R'.dbd.H). Hydrophobic AHAs are inapplicable because they would
contribute to the WSO count themselves. These AHAs are effective at
dosages ranging from about 20 to about 2000 ppm, preferably from
about 50 to about 500 ppm, based on the total water-like fluid
treated. The water-like fluid treated might be any oil-immiscible,
water-miscible phase such as brine or glycol.
[0032] Unlike the current art using strong acids, AHAs are
relatively weak acids, with pK.sub.a's >3.8, several hundred
times less acidic than the best currently-practiced art, which is
phosphorous acid, HPO(OH).sub.2. Despite their relative weakness,
however, these AHAs are effective at dosages similar to the current
art, ranging from 20 to 2000 ppm based on water, when added to any
produced water with pH greater than about 4. The current art treats
water with pH as low as 2, but most produced water has pH
>4.
[0033] Moreover, the best currently-practiced art, phosphorous
acid, corrodes carbon steel even after dilution in the process and
forms CaHPO.sub.3 scale deposits above 100 ppm. Compared to this,
the inventive compounds are far less corrosive under usage
conditions, equally non-volatile, and completely non-scaling.
Unlike amines and other cationic compounds, the invented compounds
have a wide treatment range and are compatible with existing water
clarifier treatments.
[0034] Unlike the current art that uses cationic compounds in
combination with acids, or anionic compounds without acids, this
invention optionally employs anionic polymers in combination with
acids. Anionic polymers are those that dissociate in water to
polymeric anions and individual cations. Examples include
poly-(acrylic or methacrylic acids or salts), poly(acroyl or vinyl
sulfonic acids or salts) and co-polymers of these with acrylic
amides or esters. The preferred anionic polymers are co- or
ter-polymers of (meth)acrylic acid and methyl and/or ethyl
(meth)acrylate. The co-addition of anionic polymer is effective at
dosages ranging from about 0.2 to about 20 ppm active, preferably
from about 1 to about 5 ppm, based on the total water-like fluid
treated.
[0035] The anionic polymer components of the invention are true
polymers because they have degrees of polymerization above 30. In
another non-limiting embodiment of the invention, the anionic
polymers have degrees of polymerization equal to or greater than
about 300, and in an alternate, non-limiting embodiment of the
invention, the anionic polymers have degrees of polymerization
equal to or greater than about 3000. Furthermore, in another
non-limiting embodiment of the inventive compositions herein, the
degree of polymerization may be about 300,000 or lower.
[0036] In one non-limiting embodiment of the invention, the AHA and
the anionic polymer are the only components present in the
inventive compositions that affect the characteristic or property
of removing solubilized organics from water-like fluids. No other
active components for this purpose are needed. That is, some
inventive compositions consist essentially of the AHA as defined
herein and the anionic polymers as defined herein.
[0037] Furthermore, although the anionic polymer may have hydroxyl
and carboxylic acid functionality similar to the AHA, it must be
understood that the AHA is a separate species or component from the
anionic polymer.
[0038] The relative proportions of AHA to anionic polymer, in the
cases where both are used, may vary over a wide range. In one
non-limiting embodiment of the invention, the weight ratio of AHA
to anionic polymer may range from about 1:1 to about 10,000:1. In
an alternate non-limiting embodiment of the invention, the weight
ratio of AHA to anionic polymer may range from over 50:1 to about
10,000:1. Other, non-limiting embodiments of the invention may have
the range variously at from about 60:1 to 10,000:1; about 75:1 to
about 10,000:1; and 100:1 to about 10,000:1.
[0039] The AHA is most conveniently added to the mixed oil and
water production. Alternatively, it can be added to the separated
produced water and then some or all of the produced oil or some
other convenient oil or oil-like, water-immiscible fluid mixed back
in. An "oil-like fluid phase" is defined herein as any oil phase or
phase that behaves like an oil phase by being water-immiscible. It
could be added prophylactically to water that would later contact
the separated produced oil, as, for example, in a downstream
desalter, to reduce O&G in that effluent water. In the water
contacting the oil, it converts a portion of the native water
partitioning organic anions into at least partly oil partitioning
acids. The so converted acids, after entering the oil, dimerize
into a more oil-partitioning state. Some of the oil is then
separated from the water. These more oil soluble dimers leave the
system with the oil. This depletes the remaining oil-water
interfacial region of the acid monomer, which then draws more acid
from the water into the oil. As the native acid leaves the water
for the oil, more of the acid's anion is converted to acid to
maintain the equilibrium. This process is repeated in a multiple
batch or preferably continuous manner. In this way, even the small
shift in equilibrium by the weak organic acids of this invention
results in a surprisingly large depletion of WSO. The hydroxyl
(--OH) group on the AHA keeps it in the water even at pH <2, so
that it is not counted as oil and grease for the purpose of
environmental discharge regulations. It also renders it non-toxic
to and readily biodegradable by aquatic organisms, so that it is
not, in fact, harmful to discharge (i.e., it is both legal and
ethical). It also renders it non-volatile. Volatile acids corrode
people's lungs and downstream distillation equipment.
[0040] The shift in equilibrium also consistently results, ceters
parabis, in more stable reverse emulsions and microemulsions, which
partly or even more than offset the reduction of WSOs in the
O&G. It is the O&G, not the WSO, that is actually
controlled by regulation. This occurs because the AHA neutralizes
the charge on the native anionic surfactants and intensifies the
charge on the native cationic surfactants, reducing or even
flipping the extant charge on the emulsion from negative to
positive. The standard cationic reverse breaker used to remove
these emulsions is then no longer as complementary, and may then go
from being destabilizing to being restabilizing (overtreated). It
is believed that adding an anionic polymer, instead of or in
addition to the standard cationic reverse emulsion breaker, along
with the AHA overcomes this problem and minimizes the O&G.
[0041] The removal of emulsified oil from water is known as
clarification. This is typically a multi-step process. First the
mixed oil and water production is separated into two bulk phases.
Then the emulsified oil in water is destabilized or "treated"
chemically and the oil that is "broken" out separated
gravitationally or centrifugally (e.g. cyclonically). Then the
residual emulsion is perhaps further treated chemically and the oil
droplets reduced in density by attaching them to gas bubbles. The
bubbles float and thereby "flote" the oil to the surface to be
skimmed. Finally the water can be passed through filters or
absorbers of various media prior to discharge. The anionic polymer
can be added to the water at any point prior to the final
clarification unit. The preferred addition point is prior to the
flotation unit, but addition coincident with the acid addition or
as part of a single product addition also has advantages in
simplifying application and marketing.
[0042] The invention will be further described with respect to more
specific examples that are not intended to limit its scope, but
rather to more fully illuminate it.
[0043] Test Method--The following test method was developed and
employed to evaluate candidate treatments.
[0044] Water Solubilized Organics Removal Total System Bottle
Test
[0045] 1. Pour 100 mL of untreated low pressure (LP) separator
effluent water and a production proportionate amount of LP
separator effluent oil into a 6 oz. (180 mL) prescription bottle.
Adjust total volume to leave at least 50-mL head-space.
[0046] 2. Inject the WSO test product at at least one realistic
rate (typically from 50 ppm to 1000 ppm). Include a blank.
[0047] 3. Shake the samples with an overhand 3" (8 cm) stroke 4
times per second for 12.5 seconds (50 strokes).
[0048] 4. Inject the current reverse emulsion breaker (REB) product
at its current treatment rate.
[0049] 5. Shake the samples with an overhand 3" (8 cm) stroke 4
times per second for 12.5 seconds (50 strokes).
[0050] 6. Let settle for the residence time of the gravity
separation system.
[0051] 7. Inject the current flotation aid product at its current
treatment rate.
[0052] 8. Shake the samples with an overhand 3" (8 cm) stroke 4
times per second for 12.5 seconds (50 strokes).
[0053] 9. Let settle for the residence time of the flotation
separation system.
[0054] 10. Observe and record the clarity of the water.
[0055] 11. If the water is clear, stopper the bottle with a clean,
gloved thumb, invert it and drain the contents into a separatory
funnel. (If the water is not clear, a new clarification treatment
will need to be developed to evaluate the WSO candidate.)
[0056] 12. Let settle briefly then drain the water into another
prescription bottle.
[0057] 13. Add 1 mL of 15% HCl acid to the water sample and shake a
few times to mix.
[0058] 14. Observe the volume of water in the bottle and add 20% of
that amount of Freon.
[0059] 15. Shake the samples with an overhand 3" (8 cm) stroke 4
times per second for 12.5 seconds (50 strokes).
[0060] 16. Stopper the bottle with a clean, gloved thumb and invert
it (or pour it into a separatory funnel) and drain the Freon
through an analytical grade paper filter into a beaker.
[0061] 17. Pour filtered Freon into a quartz IR cell and measure IR
absorbance on an instrument calibrated to ppm of the local Oil
& Grease. Record value as "Total Acidified Extracted
O&G".
[0062] 18. Return Freon to beaker and immediately rinse cell with
clean Freon.
[0063] 19. Fill cell with clean Freon and re-verify absorbance
blank.
[0064] 20. Add % tsp. (1.5 g) silica gel (SG) to the beaker and
swirl thoroughly but carefully.
[0065] 21. Pour the SG treated Freon through a new paper filter
into the emptied IR cell.
[0066] 22. Re-measure IR absorbance. Record value as "SG Treated
Acidified Extracted O&G".
[0067] 23. The amount of WSO in the water is defined as the
difference between SG Treated and the Total Acidified Extracted
O&G.
[0068] Note: Because of imperfect modeling of the dynamics of the
water clarfication system in the test, the total oil and grease is
not as well predicted by these test results as is the WSO, which
more reflects a shift in equilibrium. Nevertheless, a minimal level
of total oil and grease removal must be achieved in the test for
the results to be valid.
[0069] Treatment Tested. A large number of experimental treatments,
of several different chemical types, reflecting various theoretical
mechanisms of actions, were tested. Results are summarized in
Tables I and II and the FIGURE and discussed below.
1TABLE I Chemical Response, in ppm Water Clarity O&G Acid Dose
No With WSO Post- Type ppm Anionic Anionic Pre-Flote Flote*
HPO(OH).sub.2 700 dirty clear 4.1 67.5 14.1 HCl 370 dirty clear 2.2
86.6 12.2 HOAcOH (inv.) 700 dirty clear 1.1 90.9 11.1
MeSO.sub.2(OH) 700 dirty clear 3.2 83.4 13.2 HPO(OH) 500 dirty
clear 6.0 74.2 16.0 Blank 0 clear clear 27.8 50.5 37.8 *actual
performance of system = WSO + 10 ppm
[0070]
2TABLE II Dose Response of Acidic Chemicals (inventive)
H.sub.2(HPO.sub.3) HCl H(HOAcO) H(MeSO.sub.3) H(H.sub.2PO.sub.2)
Dose Active WSO Active WSO Active WSO Active WSO Active WSO Sample
mg/L mEq/L mg/L mg/L mEq/L mg/L mg/L mEq/L mg/L mg/L mEq/L mg/L
mg/L mEq/L mg/L 0 0 0 27.8 0 0 27.8 0 0 27.8 0 0 27.8 0 0 27.8 250
175 4.3 12.7 93 2.5 18.0 175 2.3 14.7 175 1.8 125 1.9 500 350 8.5
8.9 185 5.1 11.4 350 4.6 11.7 350 3.6 14.8 250 3.8 16.2 750 525
12.8 4.8 278 7.6 6.4 525 6.9 2.2 525 5.5 375 5.7 1,000 700 17.1 4.1
370 10.1 2.2 700 9.2 1.1 700 7.3 3.2 500 7.6 6.0 Confidence = +/-
15% relative SD, n = 7
[0071] A hydrophilic AHA of this invention (60 -OH acetic acid) was
added to actual produced water with a pH of 7 on a platform in the
Gulf of Mexico. The result of this trial was as follows:
3TABLE III GoM Trial Result HOAcOH WSO O&G ppm ppm ppm 0 47 56
245 22 33
[0072] A hydrophilic AHA of this invention (.alpha.-OH acetic acid)
was added to actual produced water with a pH of 6.9 on another
platform in the Gulf of Mexico. The result of this trial was as
follows:
4TABLE IV GoM Trial Result II Cationic Anionic HOAcOH REB Polymer
WSO O&G ppm ppm ppm ppm ppm 0 3.0 3.0 27 34 175 3.0 3.0 19 25
210 3.0 3.0 13 26 210 2.5 3.5 13 20 305 2.0 4.0 9 16
[0073] After reducing the O&G from 34 ppm to 25 ppm with 175
ppm AHA through reductions in WSO, further reductions in WSO were
met with a corresponding increase in insoluble oil, from 6 ppm to
13 ppm. Feeding additional anionic polymer (a methacrylic
acid:methylmethacrylate:ethylac- rylate terpolymer) at the expense
of the cationic REB brought the insoluble oil back down to 7 ppm
and allowed further reductions in the total O&G.
[0074] Corrosivity. Acid treatments are injected at high
concentration into carbon steel (1018) produced water lines using
stainless steel (316) or better quills. The resultant concentration
in the carbon steel line is typically several hundred ppm. Under
these conditions of actual use, the AHAs of this invention are
appreciably less corrosive then even the mildest, inhibited mineral
acid in use.
5TABLE V Corrosion Data (conditions unreported) Acid Conc. C1018
Steel 316L SS H.sub.2(HPO.sub.3), inhibited 70% 2.58 mpy 5.27 mpy
H(HOAcO), uninhibited 50% 8.25 mpy 0.27 mpy H.sub.2(HPO.sub.3),
inhibited 420 ppm 1.58 mpy H(HOAcO), uninhibited 300 ppm <0.01
mpy
[0075]
6TABLE VI Mud Bomb Corrosion Data Test Temp. 150 F (66.degree. C.)
Pressure 500 psi (3,400 kPa) N.sub.2 Duration 41 hrs Acid Conc.
C1018 Steel 316 SS H.sub.2(HPO.sub.3), inhibited 70% 36.4 mpy 50.5
mpy H(HOAcO), inhibited 70% 15.8 mpy 22.9 mpy
[0076] Scale Formation. The Ca complex of hydroxyacetic acid is 150
times more soluble than the 100 ppm limit of phosphorous acid.
Other metal salts are even more soluble, as shown below.
7TABLE VII Aqueous Solubility of Hydroxyacetate Metal Complexes
Metal Temp. .degree. F. (.degree. C.) Solubility, wt % Na 68 (20)
40.9 K 68 (20) 56.6 Mg 64 (18) 7.3 82 (28) 7.7 140 (60) 10.8 212
(100) 23.0 Ca 63 (17) 1.2 82 (28) 1.5 140 (60) 3.8 212 (100) 4.4 Pb
59 (15) 20.6 212 (100) 3.3 Zn 68 (20) 3.3
[0077] In the foregoing specification, the invention has been
described with reference to specific embodiments thereof. It has
been demonstrated as effective in providing methods and
compositions for removing WSO from water that has low corrosivity
with respect to the iron-alloy materials and equipment it comes
into contact with, as well as reduced scaling potential. However,
it will be evident that various modifications and changes can be
made thereto without departing from the broader spirit or scope of
the invention as set forth in the appended claims. Accordingly, the
specification is to be regarded in an illustrative rather than a
restrictive sense. For example, specific combinations of AHAs,
anionic polymers and other components falling within the claimed
parameters, but not specifically identified or tried in a
particular composition or under specific conditions, are
anticipated to be within the scope of this invention.
* * * * *