U.S. patent application number 17/147226 was filed with the patent office on 2021-05-20 for demulsifiers for crude oil based on acrylic-aminoacrylic random copolymers of controlled molecular mass.
The applicant listed for this patent is INSTITUTO MEXICANO DEL PETROLEO. Invention is credited to Juan de la Cruz Clavel Lopez, Cesar Andres Flores Sandoval, Rodrigo de Jes s Garcia Jimenez, Edgar Ivan Hernandez Carbajal, Alfonso Lopez Ortega, Fernando lvarez Ramirez, Flavio Salvador Vazquez Moreno, Gerardo Zavala Olivares.
Application Number | 20210147595 17/147226 |
Document ID | / |
Family ID | 1000005362360 |
Filed Date | 2021-05-20 |
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United States Patent
Application |
20210147595 |
Kind Code |
A1 |
Hernandez Carbajal; Edgar Ivan ;
et al. |
May 20, 2021 |
DEMULSIFIERS FOR CRUDE OIL BASED ON ACRYLIC-AMINOACRYLIC RANDOM
COPOLYMERS OF CONTROLLED MOLECULAR MASS
Abstract
Nowadays, one of the major problems of the oil industry is the
presence of large amounts of water and salts, which cannot be
efficiently removed by conventional dehydrating polymers. In
addition, the acid stimulation operations of petroleum wells cause
the chemical degradation of demulsifiers such as polyethers and
phenolic resins, reducing drastically their efficiency as water and
salt removers. Based on aforementioned, a series of new copolymers
has been developed, where the copolymers are combinations of an
acrylic and an aminoacrylic monomer and are synthesized by
semi-continuous emulsion polymerization (under starved feed
conditions), which ensures both the homogeneity of the different
chains as well as the randomness of the monomers distribution. The
solutions of one of these random copolymers have shown an
efficiency similar or superior to combinations of two or three
block copolymers (formulations), when they are applied in light or
heavy crude oils. The acrylic-aminoacrylic copolymers show good
performance as water/oil emulsion breaker initiators, coalescence
agents of water droplets and clarifiers of the remaining aqueous
phase. In addition, the chemical structure of the acrylic
copolymers confers resistance to degradation induced by abrupt pH
changes when acid stimulation operations of wells are
performed.
Inventors: |
Hernandez Carbajal; Edgar Ivan;
(Mexico City, MX) ; Flores Sandoval; Cesar Andres;
(Mexico City, MX) ; lvarez Ramirez; Fernando;
(Mexico City, MX) ; Lopez Ortega; Alfonso; (Mexico
City, MX) ; Garcia Jimenez; Rodrigo de Jes s; (Mexico
City, MX) ; Zavala Olivares; Gerardo; (Mexico City,
MX) ; Clavel Lopez; Juan de la Cruz; (Mexico City,
MX) ; Vazquez Moreno; Flavio Salvador; (Mexico City,
MX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INSTITUTO MEXICANO DEL PETROLEO |
Mexico City |
|
MX |
|
|
Family ID: |
1000005362360 |
Appl. No.: |
17/147226 |
Filed: |
January 12, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15726793 |
Oct 6, 2017 |
|
|
|
17147226 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08F 220/1806 20200201;
C10G 33/04 20130101; C08F 2800/20 20130101; C08F 220/18 20130101;
C08F 220/1811 20200201; B01D 17/047 20130101; C08F 220/1804
20200201; C10G 2300/201 20130101 |
International
Class: |
C08F 220/18 20060101
C08F220/18; B01D 17/04 20060101 B01D017/04; C10G 33/04 20060101
C10G033/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 8, 2016 |
MX |
MX/A/2016/016226 |
Claims
1. Random copolymers based on alkyl acrylate and aminoalkyl
acrylate monomers, as dehydrating agents to remove water emulsified
in crude oil with densities from 10 to 40.degree. API, having the
structural formula (2), with molecular weights between 1000 and
180,000 g/mol. ##STR00003## wherein: R.sup.1, R.sup.2, R.sup.3 and
R.sup.4 are independent radicals represented by the groups
mentioned bellow: R.sup.1 and R.sup.3.dbd.H (hydrogen), CH.sub.3
(methyl); R.sup.2.dbd.CH.sub.3 (methyl), C.sub.2H.sub.5 (ethyl),
C.sub.4H.sub.9 (n-butyl, isobutyl), C.sub.6H.sub.13 (n-hexyl,
iso-hexyl), C.sub.8H.sub.17 (2 ethyl-hexyl), C.sub.8H.sub.17
(n-octyl), C.sub.10H.sub.21 (n-decyl, iso-decyl), C.sub.12H.sub.25
(n-dodecyl), C.sub.18H.sub.37 (n-octadecyl), C.sub.8H.sub.9O
(2-phenoxyethyl), C.sub.3H.sub.7O (2-methoxyethyl), and
C.sub.5H.sub.11O.sub.2 (2-(2-methoxyethoxy)ethyl), wherein the
aliphatic chain may contain heteroatoms of the ether group, or
aromatic rings or rings with heteroatoms of the ether type;
R.sup.4.dbd.CH.sub.2NH.sub.2 (methylamine),
CH.sub.2CH.sub.2NH.sub.2 (2-ethylamine),
CH.sub.2CH.sub.2CH.sub.2NH.sub.2 (3-propylamine),
CH.sub.2CH(NH.sub.2).sub.2 (2-dimethylamino),
(CH.sub.2CH.sub.2N(CH.sub.3).sub.2) 2-(dimethylamino)ethyl,
(CH.sub.2CH.sub.2N(CH.sub.2CH.sub.3).sub.2),
2-(dimethylamino)ethyl,
(CH.sub.2CH.sub.2CH.sub.2N(CH.sub.3).sub.2),
3-(dimethylamino)propyl, (C.sub.6H.sub.12NO) N-ethylmorpholine.
wherein, x=is a number from 2 to 900; y=is a number from 2 to 900;
and "x" and "y" are in random sequences.
2. The random copolymers of claim 1, wherein R.sup.2 is selected
from the group consisting of methyl, ethyl, n-butyl, isobutyl,
n-hexyl, iso-hexyl, 2 ethyl-hexyl, n-octyl, n-decyl, iso-decyl,
n-dodecyl, n-octadecyl, 2-phenoxyethyl, and
2-(2-methoxyethoxy)ethyl.
3. The random copolymers of claim 1, wherein R.sup.2 is selected
from the group consisting of methyl, ethyl, n-butyl, isobutyl,
n-hexyl, iso-hexyl, 2 ethyl-hexyl, n-octyl, n-decyl, iso-decyl,
n-dodecyl, n-octadecyl, 2-phenoxyethyl, and
2-(2-methoxyethoxy)ethyl.
4. The random copolymers of claim 1, wherein R.sup.1 is hydrogen,
R.sup.2 is n-butyl, R.sup.3 is hydrogen, and R.sup.4 is
2-ethylamino.
5. The random copolymers of claim 1, wherein R is hydrogen, R.sup.2
is hydrogen, R.sup.3 is hydrogen, and R.sup.4 is 2-(dimethylamino)
ethyl.
6. The random copolymers of claim 1, wherein R.sup.1 is hydrogen,
R.sup.2 is n-hexyl, R.sup.3 is hydrogen, and R.sup.4 is
3-aminopropyl.
7. The random copolymers of claim 1, wherein R.sup.4 is selected
from the group consisting of methylamine, 2-ethylamine,
3-propylamine, 2-dimethylamino, and N-ethylmorpholine.
8. The random copolymers of claim 1, wherein R.sup.4 is selected
from the group consisting of methylamine, 2-ethylamine,
3-propylamine, 2-dimethylamino, and (C.sub.6H.sub.12NO)
N-ethylmorpholine.
9. A random copolymer based on alkyl acrylate and aminoalkyl
acrylate monomers, said random copolymer having the structural
formula (2) and a molecular weight between 1000 and 180,000 g/mol
##STR00004## wherein: R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are
independent radicals represented by the groups mentioned bellow:
R.sup.1 and R.sup.3.dbd.H (hydrogen), CH.sub.3 (methyl); R.sup.2 is
selected from the group consisting of methyl, ethyl, n-butyl,
isobutyl, n-hexyl, iso-hexyl, 2 ethyl-hexyl, n-octyl, n-decyl,
iso-decyl, n-dodecyl, n-octadecyl, 2-phenoxyethyl, and
2-(2-methoxyethoxy)ethyl, wherein the aliphatic chain may contain
an aromatic ring; R.sup.4 is selected from the group consisting of
methylamine, 2-ethylamine, 3-propylamine, 2-dimethylamino,
2-(dimethylamino)ethyl, 2-(diethylamino)ethyl,
3-(dimethylamino)propyl, and N-ethylmorpholine; wherein, x is a
number from 2 to 900; y is a number from 2 to 900; and "x" and "y"
are in random sequences.
10. A method for the synthesis of random copolymers based on alkyl
acrylate and aminoalkyl acrylate monomers according to claim 1, as
dehydrating agents of crude oils, wherein said synthesis is carried
out by semi-continuous emulsion polymerization.
11. A method for the synthesis of a random copolymer, based on
alkyl acrylate and aminoalkyl acrylate monomers according to claim
1, wherein the method reacts at least one alkyl acrylate monomer
and at least one aminoalkyl acrylate monomer, where the acrylate
monomer is selected from the group consisting of methyl acrylate,
ethyl acrylate, butyl acrylate, n-amyl acrylate, isobornyl acrylate
isobutyl acrylate, tert-butyl acrylate, hexyl acrylate,
2-ethylhexyl acrylate, 3,5,5-trimethylhexyl acrylate,
2-methoxiethyl acrylate, 2-phenoxiethyl acrylate,
4-tert-butylcyclohexyl acrylate, octyl acrylate, isodecyl acrylate,
decyl acrylate, lauryl acrylate, tridecyl acrylate, octadecyl
acrylate, and behenyl acrylate.
12. A method for the synthesis of a random copolymer based on alkyl
acrylate and aminoalkyl acrylate monomers according to claim 1,
wherein the method reacts at least one alkyl acrylate monomer and
at least one aminoalkyl acrylate monomer, wherein the aminoacrylic
monomer is selected from the group consisting of 2-ethylamino
acrylate, 2-ethylamino methacrylate, 2-(dimethylamino)ethyl
acrylate, 2-(dimethylamino)ethyl methacrylate, 3-propylamino
acrylate, 3-(dimethylamino)propyl acrylate, 2-(diethylamino)ethyl
acrylate, 2-(diethylamino)ethyl methacrylate, and
2-N-ethylmopholine methacrylate.
13. The method of synthesis of claim 11, wherein said the
aminoacrylic monomer is selected from the group consisting of
2-ethylamino acrylate, 2-ethylamino methacrylate,
2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl
methacrylate, 3-propylamino acrylate, 3-(dimethylamino)propyl
acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl
methacrylate, and 2-N-ethylmopholine methacrylate.
14. A method of producing a dehydrating agent for crude oil
comprising adding an organic solvent to the random copolymer of
claim 1, wherein said organic solvent is selected from the group
consisting of dichloromethane, methanol, ethanol, isopropanol,
chloroform, benzene and its derivatives, toluene, xylene, turbosine
and naphtha, and mixtures thereof.
15. The method of producing the dehydrating agent according to
claim 14, comprising adding said organic solvent with said random
copolymer in an amount to provide said dehydrating agent with said
random copolymer in an amount of 10 wt % to 50 wt %.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. Ser.
No. 15/726,793, filed Oct. 6, 2017, which claims the benefit of
Mexican Patent Application No. MX/a/2016/016226 filed Dec. 8, 2016,
the entire contents of which are incorporated herein by
reference.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention corresponds to the field of chemical
products for petroleum conditioning, particularly to demulsifiers.
This invention is related to the application of copolymers based on
alky acrylate-aminoalkyl acrylate monomers to control the formation
of water-in-oil (W/O) emulsions, in order to remove water and salts
(dissolved in the aqueous phase) from triphasic separation units
and for crude oils with densities between 10 and 40.degree.
API.
BACKGROUND OF THE INVENTION
[0003] The removal of large amounts of water and salts is one of
the major problems of petroleum industry. Emulsified water must be
counted among the contaminants of crude oil. Salt may be dissolved
in congenital water and dispersed as granules produced by the
erosion of saline domes during the petroleum extraction. Nowadays,
increasingly heavier crude oils, with larger amounts of resins and
asphaltenes, are obtained and emulsions with smaller water
dropplets are formed because they are stabilized by the aromatic
compounds. One of the most common methods to destabilize water/oil
emulsions and to remove the salts dissolved in water is the
addition of chemical compounds with surfactant properties.
[0004] Currently, the extraction of heavy and extra-heavy crude
oils carrying extremely stable emulsions, along with the fall of
oil prices, make necessary the development of demulsifying more
efficient chemical treatments, capable of removing larger amounts
of water and salts at lower prices.
[0005] These chemical treatments consist of injecting the
dehydrating agent into the three-phase separators or, in some
cases, at the bottom of the well, in order to achieve the longest
contact time with the emulsion. Dehydrating agents are often a
mixture of amphipilic surfactants dissolved in an aromatic
hydrocarbon solvent (benzene, toluene, and xylene), dispersed by
diffusion and convection in crude oil and adsorbed at the water/oil
interface of the water drops. The processes of adsorption and
displacement and, therefore, the effectiveness of demulsifiers,
depends on their chemical structure, pH of the aqueous phase, salt
content and temperature. To ensure a good performance of
demulsifier agent, the following features must be accomplished:
dissolution of the continuous oil phase, diffusion at the oil/water
interphase (considering that that the concentration of demulsifier
is low), suppression of the interfacial tension gradient and
moisturizing and subsequent incorporation of the solids in the
removed water. However, the design of demulsifier chemical products
depends on the features of crude oils, which are unique for each
field and present specific emulsification problems, so the
demulsifier must be adapted to every well. An appropriate selection
of chemical products in a good proportion is required for an
optimal treatment, although it is difficult to standardize a dosage
interval.
[0006] The main chemical products currently used as crude oil
demulsifiers and some application properties are summarized in
Table 1.
TABLE-US-00001 TABLE 1 Chemical products currently use as
demulsifiers. Product Demulsifier property Polyethers Good
demulsifiers that cause a slow settling of water droplets, but
overdosing leads to the formation of inverse emulsions (O/W).
Resins Good demulsifiers that cause a rapid settling of water
droplets and separate water comes out clean. Polyglycols These
compounds require mixing with other chemical products for
application. Di-epoxides Excellent demulsifiers but causing a slow
settling of water droplets. Urethanes Excellent demulsifiers but
causing a slow settling of water droplets. Polyalkylenes Poor
demulsifiers, slow settling of water droplets. Sulfonates Good
humectants of solids and these have the capacity to settle water
droplets, overdosing does not cause inverse emulsions (O/W), but
these can cause precipitation of iron sulphide particles in the
separated water. Polyamines Slow effects on the settling of water
drops. Alkanolamines Fast effects on the settling of water drops.
Polyesters Good demulsifiers that cause a slow settling of water
droplets, but overdosing leads to the formation of inverse
emulsions (O/W). Polyesteramines They are agents of surface active;
hydrating at low dosages, overdosing produces inverse emulsions
(O/W). Oxialkylates Good hydrating agents used in mixtures.
[0007] By far, chemical compounds with largest range of application
are the polyethers, mainly those who possess a block structure with
a central sequence of hydrophobic propylene polyoxide and chain
ends with sequences of hydrophilic ethylene oxide. Hydrophobic
blocks in such copolymers ensure their dissolution and diffusion in
crude oil, whereas hydrophilic blocks allow the destabilization of
the water/oil emulsion interface. Among the main background of
application of this compounds family, can be mentioned the U.S.
Pat. Nos. 2,425,845 [1] and 3,334,038 [2], which protect the
production process of EO-PO-EO copolymers, indicating the use as
initiators of the polymerization of the central sequence of
propylene polyoxide, salts derived from the following alcohols:
ethylenglycol, 1,2-propylenglycol, 1,3-propylenglycol,
butylenglycols, diethylenglycol, dipropylenglycol,
triethylenglycol, tripropylenglycol, as well as other aliphatic
glycols.
[0008] Theoretical and experimental studies have allowed
stablishing that the performance of dehydrating copolymers depends
on molecular parameters such as: a) chemical structure, b)
composition and c) molecular mass (length of the polymeric chain).
This last parameter was studied experimentally by Cendejas et al.
[3], who observed that copolymers of low molecular mass are more
effective for dehydrating light crude oils, whereas copolymers of
greater molecular mass are required to demulsify efficiently heavy
crude oils. Indeed, there is an optimal molecular mass to achieve
the best petroleum dehydrating. On the other hand, the mechanism by
which the block copolymers achieve to destabilize an emulsion has
been elucidate through theoretical methods by Alvarez et al.
[4].
[0009] Another patent, U.S. Pat. No. 3,835,060 [5], reports a
similar technology of polyethers application, which consists of
breaking the crude oil emulsion, using a combination of alkyl ether
sulfates and block copolymers of polyoxiethylene-polyoxipropylene,
where R represents alkyl groups, n=1-10 and M is an alkaline metal,
alkaline earth metal or a quaternary nitrogen (see formula 1, alkyl
ether sulfate of polyglycol). It is reported that, after dosing the
mixture in a range of 20-140 ppm, the breakdown of emulsion starts
at 120 minutes, reaching a removal of 35% of emulsified water;
however, the type of oil used and its characteristics were not
reported.
##STR00001##
[0010] U.S. Pat. No. 5,445,765 [6] discloses demulsifier products
of the type of polyethylenamines alkoxylated with propylene oxide
and ethylene oxide, which were evaluated in a certain crude oil
extracted in West Africa, at dosages from 0.1 until 200 ppm, in a
range of temperatures between 10 and 130.degree. C., reaching a
removal of 47% of emulsified water after 3 h.
[0011] U.S. Pat. No. 5,609,794 [7] discloses the use of
polyalkylglycol and ethylene oxide adduct, which is esterified with
an anhydride to form a diester, which is subsequently to make react
with vinyl monomers and so on, until form different esters.
Formulations are applied in a range of temperature from 7 to
80.degree. C., in concentration from 10 to 1500 ppm and it is dosed
to crude oil (without specifying whom) and in different currents
(turbosine, gasoline, lubricants oil and others). This document
mentions that water removed reaches 40 vol. % in some minutes,
without specifying the exact interval of time.
[0012] The use of vinyl polymers as demulsifiers of water/oil or
oil/water emulsions has been reported in literature. For example,
it is known that homopolymers and copolymers of monoalylamines have
been employed to break up in water emulsions in a synthetic oil,
prepared using as dispersed phase a commercial motor oil SAE 10W30
and as stabilizing agents a mixture of dodecyl and tetradecyl
alcohols (U.S. Pat. No. 4,614,593 [8], demulsifying of oil-in-water
emulsions).
[0013] The application of water-dispersible terpolymers to remove
emulsified oils in wastewater, mainly to purify wastewaters that
have organic contaminants, has also been proposed. Terpolymers were
synthesized starting from acrylamide,
3-acrylamido-propylmethylamonium or hydrophobic monomers such as
alkylacrylamides (U.S. Pat. No. 4,741,835 [9], oil-in-water
emulsion breaking with hydrophobically functionalized cationic
polymers).
[0014] Although in both references (U.S. Pat. Nos. 4,614,593 [10]
and 4,741,835 [9]) could be observed surfactant properties of vinyl
polymers and polyacrylamides, the emulsions employed for evaluation
are much easier to destabilize that water-in-oil emulsions
stabilized by asphaltenes.
[0015] It has also been reported that copolymers based on chains of
lipophilic no-ionic monomers and ammonium salts are effective to
break up or to inhibit the formation of oil-in-water or
water-in-oil emulsions in the desalting process of California crude
oils (138<T<150.degree. C.). Copolymers comprise a cationic
monomer as 2-acryloyloxyethyltrimethyl ammonium chloride and a
no-ionic lipophilic unit of type methyl methacrylate, butyl
acrylate, n-isopropylacrylamide and N,N-dimethylacrylamide (U.S.
Pat. No. 5,921,912 [11], copolymer formulations for breaking
oil-in-water emulsions). The copolymers, obtained by solution or
emulsion polymerization, are water soluble, so they could be
applied directly in emulsions of the type crude oil-in-water.
However, the copolymers hydrophilicity make their dosage in crude
oil (to break up water-in-oil emulsions) very difficult, and the
previous formation of an emulsion of the aqueous solution of the
copolymers dispersed in some organic solvent, with the aid of
another polymeric surfactant, is necessary. The difficulty to
disperse these copolymers directly in crude oil complicates their
application as destabilizers of water-in-oil emulsion. On the other
hand, it is well known that one of the main factors that determines
the efficiency of a demulsifier is its molecular mass [3], [4]. In
the aforementioned U.S. Pat. No. 5,921,912 [11] is reported a range
of application between Mn 20,000 and 20,00,000 g/mol, but any
mechanism or procedure to control of the copolymers molecular mass
during the solution or emulsion was not mentioned.
[0016] In a similar way, U.S. Pat. No. 5,730,905 [12] (Method of
resolving oil and water emulsions) reports the inhibitor and
suppressor effects of the formation of water/oil and oil/water
emulsions (138<T<150.degree. C.). Copolymers comprise a
combination of acrylamide and 2-acryloxyethyltrimethylammonium
chloride. The authors pointed out that their copolymers have
application in the desalting of Californian crude oils, under
refinery conditions, for emulsions that contain between 2 and 50%
of crude oil, at 150.degree. C. It is important to emphasize that
with these amount of oil, oil/water emulsions are mainly formed. As
in the previous case, demulsifying temperature is very high
(150.degree. C.). By another way, it is well known that one of the
main factors that determines the efficiency of demulsifiers is
their molecular mass [3], [4]. However, in U.S. Pat. No. 5,730,905
[12] is reported that copolymers are synthesized in a very broad
range of molecular mass (from 2 000 000 to 40 000 000 g/mol). Such
copolymers are difficult to handle, because of their high viscosity
and must be dissolved in water. Such materials can be applied into
a water/oil emulsion, as in the case of U.S. Pat. No. 5,921,912
[11], only if an aqueous solution is previously emulsified in an
organic solvent. Finally, it should be emphasized that these
demulsifier copolymers are prepared by inverse emulsion
polymerization, losing the advantage of use water as dispersion
medium.
[0017] A more efficient demulsifier system is reported in U.S. Pat.
No. 5,607,574 [13](Method of breaking reverse emulsions in crude
oil desalting system) and it consists of adding into emulsions
containing between 51 and 99% of oil, in a high range of
temperature (65<T<150.degree. C.), a combination of aluminum
chlorohydrate and polyamines.
[0018] On the other hand, in U.S. Pat. No. 5,156,767 [14] (Emulsion
breaking using alkylphenol-polyethylene oxide-acrylate polymer
coated coalescer material) is reported that polymers, having an
alkylphenol, ethylene oxide and an acrylic monomer, which are
efficient as destabilizers of water-in-oil emulsions. Such polymers
were evaluated in a mixture of Hutton crude oil and brine of
Tisdale field.
[0019] Xu Wei et al. reported in 2011, in the CN Patent 101255354 B
[15] (Non-polyether type thick oil demulsifying agent and
preparation thereof), the use of copolymers of butyl acrylate and
acrylic acid as demulsifiers of crude oil. These copolymers were
prepared by solution polymerization, using an organic solvent as
dispersion medium and an initiator, as the bis-azobutyronitrile,
soluble in the organic phase. Authors [15] mention problems to
control the homogeneity of the synthesized copolymers, so the
monomers had to be added in portions (batch method) or by dropping
(no specific controls of addition feed are mentioned). Inventors
don't either report either the control of molecular mass for
specific applications in different types of crude oils. Finally, Xu
Wei et al. ensured a good breaking capacity and a remarkable
clarification of the aqueous phase using these copolymers.
[0020] The use as demulsifiers of synthesized copolymers based on
acrylic monomers and oxyalkylates (derivatives of ethylene oxide,
propylene oxide, etc.). is detailed in U.S. Pat. No. 5,472,617 [16]
(Method of demulsifying crude oil and water mixtures with
copolymers of acrylates or methacrylates and hydrophilic
comonomers) The process of synthesis of these copolymers is
complex, because it involves several stages to prepare the
comonomers and, once obtained the copolymers, these are submitted
to further changes. In the elaboration of these materials are
employed organic solvents such as xylene and toluene. The
assessment as demulsifiers of these copolymer was determined in
crude oils from north Germany, the North Sea, the Gulf States of
U.S., the Near and Middle East, as well as Africa. However, in none
of those cases the API degrees of crude oils are mentioned, in
spite this characteristic is fundamental to estimate the real
efficiency as demulsifiers of block copolymers.
[0021] One of the properties that a demulsifier must provide is the
clarification of the aqueous phase, i.e., the removal of residual
amounts of oil in the remaining water. In EP 595156A1 Patent [17]
(New dispersion polymers for oil field water clarification) is
claimed the use of polymers based on the copolymerization of
water-soluble monomers derivatives of quaternary ammonium salts
obtained from benzyl chloride and acrylates such as
dimethylaminoethyl or diethylaminoethyl acrylates. The Copolymers
are prepared by emulsion polymerization from a seed or "situ",
using as free radical source an azo-initiator. In the document, the
control of the addition feed of monomers is not mentioned. The
molecular masses of the obtained copolymers are between 10 000 and
10 000 000 g/mol. Authors point out that they did not find an
influence of the copolymer molecular weight on their clarifying
power of the water phase produced in oil fields. It is not
mentioned in the document that the water-soluble acrylic copolymers
present properties as breakers or coalescence agents of water/oil
emulsions.
[0022] In U.S. Pat. No. 5,100,582 [18] the use of a tetrapolymer of
methyl methacrylate, butyl acrylate, acrylic acid and methacrylic
acid, as well as a pentapolymer synthesized from methyl
methacrylate, butyl acrylate, acrylic acid, methacrylic acid and
styrene is disclosed as a destabilizer of water/oil emulsions. Both
polymers are water-soluble and were evaluated in a "crude oil
replicate", i.e., a mixture of heptane and toluene. In the
document, the highly stabilizing effect of asphaltenes in water/oil
emulsions is not taken in account, but it is necessary to remark
that the asphaltene effect was not emulated by the mixture of
organic solvents used to evaluate the tetrapolymer and
pentapolymer. The lipophobicity of both polymers makes very
difficult their application in crude oil.
[0023] The use of vinyl-acrylic copolymers as dehydrating agents of
crude oils was reported by D. Ramirez [19] (pp. 120-126). These
chemical products, synthesized by emulsion polymerization, showed a
high performance to remove water and salts from crude oils. DPD
simulation of the system allowed demonstrating that vinyl-acrylic
copolymers induce the rupture of water/oil and oil/water emulsions
through a gap formation mechanism [19] (p. 136).
[0024] Gonzalez Palacios [20] studied in 2015 the demulsifying
effect of a series of copolymers based on two acrylic monomers. The
strong influence of the polymer molecular mass on its performance
as water remover was confirmed in this work and it was concluded
that there is an ideal molecular weight value to achieve a maximum
dehydration. However, acrylic-acrylic polymers needed to be added
in large doses (>1500 ppm) in order to remove completely the
aqueous phase.
[0025] Recently, Atta et al. [21] reported the use of poly ionic
liquids of acrylic type to destabilize emulsions of heavy oil and
water. Copolymers employed as demulsifiers were synthesized by
solution polymerization, employing tetrahydrofuran as solvent.
Authors observed a remarkable clarifying ability of the aqueous
phase removed from the emulsion by dosed copolymers [21].
[0026] A similar case was studied by Martinez Gallegos [22], who
reported in 2016 the use of copolymers of 2-carboxiethyl acrylate
(F) and 2-(dimethylamino)ethyl methacrylate (E), in a ratio FIE:
50/50 and 70/30 wt %, as dehydrating agents of crude oil. Such
copolymers were insoluble in organic solvents, so they had to be
dissolved in water under basic conditions. Although with this
copolymer, obtained from the combination of an acrylic monomer and
another aminoacrylic monomer, was reached high water removals, the
need to add these acrylic demulsifiers in aqueous solutions
constitutes a disadvantage for their application to destabilize
water/crude oil emulsions in the field. From the environmental
point of view, the hydrophilicity of these acrylic-aminoacrylic
copolymers (as well as those of U.S. Pat. No. 5,921,912 [11],
previously analyzed) represents also a difficulty [23].
[0027] Subsequently, Garcia Jimenez [24] reported certain random
copolymers based on acrylics, unlike the previous case, which can
be dissolved in organic solvents such as xylene. These compounds
proved to be very efficient as water removers in both light and
heavy crude oils. However, neither the chemical structures nor the
contents of the monomers used to synthesize the demulsifier
copolymers of crude oil have been reported anywhere in the
document, being impossible to infer which combinations of the
numerous acrylic monomers are capable to dehydrate crude oils.
However, in that document, a theoretical study was presented,
showing that the acrylics are capable of inducing the coalescence
of water droplets in crude oil by means of a molecular drag
mechanism.
[0028] The development of novel random copolymers of acrylic
monomers and aminoacrylic with properties as breakers of
water/crude oil emulsions, drop coalescers and clarifiers of the
aqueous phase, is shown in the present invention. The synthesis of
these dehydrating agents of crude oil was carried out by
semi-continuous emulsion polymerization a process developed in the
Mexican Petroleum Institute, which has shown its utility for the
synthesis of other chemical products employed to condition crude
oil, such as viscosity reducers [25] and defoamers [26]. In the
mentioned process, emulsion polymerization was carried out under
starved feed conditions, which ensures the copolymer homogeneity
(no composition drifts) and a random monomer distribution in the
chain. the elaboration process requires the use of chain-transfer
agents, molecules that allow controlling the average molecular mass
of the polymeric chains. This molecular parameter is of great
importance, since the efficiency of dehydrating process of light or
heavy crude oils depends largely on it. The presence of suitable
amounts of acrylic monomers in the copolymer allows their
dissolution in the crude oil, while the aminoacrylic units in the
chain interact with the aqueous phase. The proportions of the
acrylic and aminoacrylic monomers were adjusted in order to obtain
copolymers soluble in the organic phase, so they can be applied
directly in crude oil and without the risk of being trained by the
remaining aqueous phase [23]. Unlike other demulsifiers reported in
the literature, these acrylic-aminoacrylic copolymers were directly
evaluated in light and heavy crude oils. Molecular characteristics
of novel acrylic-aminoacrylic copolymers (composition and molecular
mass) could be adjusted according to characteristic of each crude
oil, optimizing their performance as dehydrating agents and thus
showing a better efficiency/cost ratio than commercially available
dehydrating agents.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0058] Firstly, FIGS. 1 to 3 report the results of the performance
of a series of copolymers based on alkyl acrylate-alkylamine
acrylate monomers, used as dehydrating agents of heavy crude oil of
12.31.degree. API Subsequently, the results of the assessment of a
second series of acrylic-amino acrylic copolymers applied in heavy
crude oil of 18.77.degree. API are shown in FIG. 4. Finally, the
performance as demulsifiers of other set of acrylic-aminoacrylic
copolymers dosed in light crude oil of 38.71.degree. API is
described in FIG. 5.
[0059] In FIG. 1 is reported the performance of random copolymers
based on acrylic/amino acrylic monomers, labeled in the present
invention as AK371 and AK371-L, with a ratio of A-monomer of 70 wt
% and K3-monomer of 30 wt %. The first copolymer, AK371, was
synthesized in a semi-continuous reactor, whereas the AK371-L
copolymer was obtained in batch reactor. Both random copolymers
were evaluated as demulsifier agents in heavy crude oil of
12.31.degree. API, at concentrations of 500 and 1000 ppm and
compared to untreated crude oil (blank). A clear improvement of the
performance as demulsifier of the AK371 copolymer, compared to the
copolymer obtained in batch reactor, was observed.
[0060] FIG. 2 allows observing the demulsifier performance of the
acrylic/amino acrylic random copolymer labeled as AK371, with a
ratio of A of 70 wt % and K3 with 30 wt %, synthesized in a
semi-continuous reactor, compared to the FDH-1 commercial
formulation. Both were evaluated as demulsifier agents in heavy
crude oil of 12.31.degree. API, at concentrations of 500 and 1000
ppm; likewise the performance of both products were compared to the
behavior of the untreated crude oil (blank).
[0061] In FIG. 3 are shown images of the testing bottles once the
dehydrating assessment ended; a) bottle dosed with the FDH-1
commercial product, at 1000 ppm, in the Ayin-09 crude oil
(12.31.degree. API) and b) bottle dosed with the AK272
acrylic/amino acrylic copolymer, at 1000 ppm, in the Ayin-09 crude
oil (12.31.degree. API).
[0062] FIG. 4 reports the demulsifier activity of acrylic/amino
acrylic random copolymers labeled as: AK261 (with a ratio of A
monomer of 60 wt % and K2 monomer of 40 wt %); AK271 (with a ratio
of A monomer de 70 wt % and K2 monomer of 30 wt %); AK281 (with a
ratio of A monomer of 80 wt % and K2 monomer of 20 wt %); AK291
(with a ratio of A monomer of 90 wt % and K2 monomer of 10 wt %).
All copolymers were synthesized by semi-continuous process and,
once obtained, compared with the FDH-1 commercial formulation. The
evaluation was carried out in heavy crude oil of 12.31.degree. API
at concentration of 1000 ppm; all products are compared with
untreated crude oil without treatment (blank).
[0063] FIG. 5 shows the demulsifier activity of three acrylic/amino
acrylic random copolymers labeled as AK371, AK372 and AK373, with a
composition of A monomer of 70 wt % and K3 monomer of 30 wt %.
Molecular mass of these copolymers, obtained in semi-continuous
reactor, were adjusted a different values (12160, 15430 and 24312
g/mol). Their performance as dehydrating agents of heavy crude oil
of 18.77.degree. API, at concentrations of 500 and 1000 ppm, was
compared to that of FDH-1 commercial formulation. Likewise, the
emulsion destabilization was compared with the colloidal stability
of untreated crude oil (blank).
[0064] In FIG. 6 are shown images of the testing bottles once ended
the evaluation of dehydrating agents: a) testing bottle dosed with
FDH-1 commercial product, at 500 ppm in the Ayin-04 crude oil
(18.77.degree. API) and b) testing bottle dosed with the AK272
acrylic/amino acrylic copolymer, at 500 ppm, in the Ayin-9 crude
oil (18.77.degree. API).
[0065] In FIG. 7 is reported the demulsifier activity of a series
of acrylic/amino acrylic random copolymers, labeled in the present
invention as: BK171, BK172, BK173 and BK174 (all with a content of
B monomer of 70 wt % and K1 amino acrylic monomer of 30 wt %).
Their molecular mass were adjusted during the polymerization in
semi-continuous reactor. The efficiency of these copolymers as
water removers in light crude oil (38.71.degree. API) was compared
to that of the FDH-1 commercial formulation, being dosed everyone
at 100 ppm. The colloidal stability of water/oil emulsion employed
as blank is also reported.
[0066] Images included in FIG. 8 show the testing bottle once ended
the evaluation of two dehydrating agents: a) Testing bottle dosed
with the FDH-1 commercial product, at 100 ppm, in the Ayin-01 crude
oil (38.71.degree. API) and b) Testing bottle dosed with the BK172
acrylic/amino acrylic copolymer, at 100 ppm, in the Ayin-01 crude
oil (38.71.degree. API).
DETAILED DESCRIPTION OF THE INVENTION
[0067] The present invention consists of the synthesis of random
copolymers based on alkyl acrylates and amino alkyl acrylates
(polymers with random sequences of two monomers in the polymeric
chain) and their evaluation as dehydrating agents in crude oils
with densities between 10 and 40.degree. API.
[0068] Random copolymers based on alkyl acrylate and alkylamino
acrylate as dehydrating agents were prepared employing the
following method. This method is illustrative and not imply any
limitation:
[0069] Random copolymers based on alkyl acrylate and alkylamino
acrylates are synthesized by semi-continuous emulsion
polymerization as a latex, (the synthesis method is described in
Mexican patent MX 338861B [27]). In this patent, the monomers are
fed from an addition tank to the main reactor under starved feed
conditions, which guarantees a higher homogeneity in the
synthesized copolymers and a random distribution of the monomeric
units in the chains [28]. Additionally, the semi-continuous process
allows controlling the exothermy of the reaction by dosing the
pre-emulsion feed to the polymerization reactor. Only for
comparison, a copolymer was synthesized by emulsion polymerization
in a batch reactor [29], a procedure that does not guarantees the
product homogeneity nor the control of the reaction exothermy. The
copolymers are prepared as latex, which is a dispersion of
polymeric particles in water, easy to handle and it avoids the
usage of organic solvents. Latex is dewatered by distillation at
temperatures from 80 to 120.degree. C. and, at the same time, a
suitable organic solvent is added to allow its final application as
demulsifying agent in crude oils with densities of 10 to 40.degree.
API, employing solvents whose boiling point falls within the range
of temperature between 35 to 200.degree. C., such as:
dichloromethane, methanol, ethanol, isopropanol, chloroform,
benzene and its derivatives, toluene, xylene, jet fuel, naphtha,
individually or mixed. The amount of copolymer in the solution is
between 10 and 50 wt %.
[0070] In scheme (2) is shown the structure of the different random
copolymers based on alkyl acrylate/alkylamino acrylates, comprised
in the present invention, preferably alkyl ester of acrylic acid or
methacrylic acid:
##STR00002##
wherein: R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independent
radicals represented by the groups mentioned bellow: R.sup.1 and
R.sup.3.dbd.H (hydrogen), CH.sub.3 (methyl); R.sup.2.dbd.CH.sub.3
(methyl), C.sub.2H.sub.5 (ethyl), C.sub.4H.sub.9 (n-butyl,
isobutyl), C.sub.6H.sub.13 (n-hexyl, iso-hexyl), C.sub.8H.sub.17 (2
ethyl-hexyl), C.sub.8H.sub.17 (n-octyl), C.sub.10H.sub.21 (n-decyl,
iso-decyl), C.sub.12H.sub.25 (n-dodecyl), C.sub.18H.sub.37
(n-octadecyl), C.sub.8H.sub.9O (2-phenoxyethyl), C.sub.3H.sub.7O
(2-methoxyethyl), C.sub.5H.sub.11O.sub.2
(2-(2-methoxyethoxy)ethyl). This aliphatic chain may contain
heteroatoms of the ether group, as well as aromatic rings or rings
with heteroatoms of the ether type. R.sup.4.dbd.CH.sub.2NH.sub.2
(methylamine), CH.sub.2CH.sub.2NH.sub.2 (2-ethylamine),
CH.sub.2CH.sub.2CH.sub.2NH.sub.2 (3-propylamine),
CH.sub.2CH(NH.sub.2).sub.2 (2-dimethylamino),
(CH.sub.2CH.sub.2N(CH.sub.3).sub.2) 2-(dimethylamino)ethyl,
(CH.sub.2CH.sub.2N(CH.sub.2CH.sub.3).sub.2) 2-(dimethylamino)ethyl,
(CH.sub.2CH.sub.2CH.sub.2N(CH.sub.3).sub.2).sub.3-(dimethylamino)propyl,
(C.sub.6H.sub.12NO) N-ethylmorpholine.
[0071] Wherein, additionally:
x=is a number from 2 to 900. y=is a number from 2 to 900. "x" and
"y" can be random sequences. Average number molecular masses are
comprised in the ranges from 1000 to 180 000 g/mol.
[0072] The following describes, by way of example, which does not
imply any limitation, the monomers used in the synthesis of the
copolymers, object of this invention: methyl acrylate, ethyl
acrylate, butyl acrylate, n-amyl acrylate, isobornyl acrylate
isobutyl acrylate, tert-butyl acrylate, hexyl acrylate,
2-ethylhexyl acrylate, 3,5,5-trimethylhexyl acrylate,
2-methoxiethyl acrylate, 2-phenoxiethyl acrylate,
4-tert-butylcyclohexyl acrylate, octyl acrylate, isodecyl acrylate,
decyl acrylate, lauryl acrylate, tridecyl acrylate, octadecyl
acrylate or behenyl acrylate; on the other hand, it described the
alkylamino acrylates used in this invention, it does not imply any
limitation: 2-ethylamino acrylate, 2-ethylamino methacrylate,
2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl
methacrylate, 3-propylamino acrylate, 3-(dimethylamino)propyl
acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl
methacrylate, 2-N-ethylmopholine methacrylate.
[0073] The method consists in adding an effective amount of random
copolymer, based on alkylacrylate and alkylamino acrylate, to crude
oils with densities from 10 to 40.degree. API, at concentrations
between 10 and 2000 ppm, in order to induce the demulsification of
aforementioned crude oils.
[0074] The present invention will be described drawing upon a
specific number of examples, which are considered illustrative but
do not imply any limitation. Once obtained, copolymers, based on an
alkyl acrylate and an alkylamino acrylate, were characterized using
the following instrumental methods:
[0075] 1.--Size exclusion chromatography (SEC), in a size exclusion
chromatograph Agilent.RTM. model 1100, with PLgel column and using
tetrahydrofuran (THF) as eluent, to calculate the copolymer
molecular mass distribution and polydispersity index (1).
[0076] 2.--Fourier Transform Infrared spectroscopy (FTIR), in a
FTIR spectrometer model Thermo Nicolet.RTM. AVATAR, 330 using the
method of film technique with OMNIC.RTM. software, version 7.0.
[0077] The average molecular masses and polydispersity index of the
copolymers based on alkyl and alkylamino acrylates are shown in
Tables 2, 3 and 4; the spectroscopic characteristics of some
synthesized random copolymers based on an alkyl acrylate and an
alkylamino acrylate, which does not imply any limitation, are also
given:
[0078] The results of the synthesis of different alkyl/amino
polyacrylates (R.sup.1=hydrogen, R.sup.2=n-butyl, R.sup.3=hydrogen,
R.sup.4=2-ethylamino), which does not imply any limitation, are
reported in Table No. 2:
TABLE-US-00002 TABLE No. 2 Weight composition (wt %), synthesis
method, average number molecular mass (Mn, measured by SEC) and
polydispersity index (I) of a series of acrylic-aminoacrylic
copolymers synthesized as examples.. Weigth ratio Mn Copolymer (wt
%) Synthesis method (g/mol) I AK271-L 70/30 Batch 18900 3.2 AK261
60/40 Semi-continuous 24147 2.3 AK271 70/30 Semi-continuous 26269
2.3 AK281 80/20 Semi-continuous 26540 2.4 AK291 90/10
Semi-continuous 28002 2.5 AK272 70/30 Semi-continuous 14132 1.8
The results of the synthesis of a series of alkyl polyacrylates
(R.sup.1=hydrogen, R.sup.2=n-butyl, R.sup.3=methyl,
R.sup.4=2-(dimethylamino) ethyl), which does not imply any
limitation, are reported in Table No. 3:
TABLE-US-00003 TABLE No. 3 Molecular mass in number (Mn),
polydispersity index (I) of acrylic-aminoacrylic copolymers
measured by SEC, besides its composition in weight (wt %) and
synthesis method for each example. Copolymer Weigth ratio (wt %)
Synthesis method Mn (g/mol) I AK371 70/30 Semi-continuous 24312 2.5
AK372 70/30 Semi-continuous 15430 2.0 AK373 70/30 Semi-continuous
12160 1.7
The results of a series of alkyl polyacrylates (R.sup.1=hydrogen,
R.sup.2=n-hexyl, R.sup.3=hydrogen, R.sup.4=3-aminopropyl, which
does not imply any limitation, are listed in Table No. 4:
TABLE-US-00004 TABLE No. 4 Molecular mass in number (Mn),
polydispersity index (I) of acrylic-aminoacrylic copolymers
measured by SEC, besides its composition in weight (wt %) and
synthesis method for each example. Weigth ratio Mn Copolymer (wt %)
Synthesis method (g/mol) I BK171 70/30 Semi-continuous 23770 2.4
BK172 70/30 Semi-continuous 14302 1.8 BK173 70/30 Semi-continuous
11161 1.6 BK174 70/30 Semi-continuous 9860 1.4
EXAMPLES
[0079] The following examples are presented to illustrate the
spectroscopic characteristics of the copolymers based on alkyl
acrylate and alkylamino acrylate, employed as dehydrating agents of
crude oils with API densities between 10 and 40.degree. API. These
examples should not be regarded as limiting of what is claimed
here.
Series AK
[0080] Random copolymer based on alkyl acrylate/alkylamino
acrylate, I.R. .nu. cm.sup.-1: 3395, 2959, 2938, 2873, 1732, 1589,
1457, 1380, 1251, 1164, 1098, 1066, 941, 738.
Series BK
[0081] Random copolymer based on alkyl acrylate/alkylamino
acrylate, I.R. .nu. cm.sup.-1: 3446, 2959, 2934, 2873, 1732, 1455,
1379, 1252, 1163, 1117, 1065, 942, 840.
[0082] Evaluation of random copolymers based on alkyl acrylate and
alkylamino acrylate as dehydrating agents of crude oils with
densities between 10 and 40.degree. API.
Different concentrated solutions of each one of the synthesized
copolymers were prepared, since 5 to 40 wt %, employing solvents
with boiling point falling within the range of temperature from 35
to 200.degree. C., as dichloromethane, methanol, ethanol,
isopropanol, chloroform, benzene and its derivatives, toluene,
xylene, jet fuel, naphtha, individually or mixed. A small volume of
the solvent was added to the solution hindering that any solvent
effect on the water removal from crude oil. Copolymers based on
alkyl acrylate and aminoalkyl acrylate were evaluated at a
concentration in the range from 10 to 2000 ppm. Polymers were
simultaneously evaluated and were compared to a commercial
dehydrating formulation (FDH-1), widely used in the oil
industry.
[0083] The polymers composing the FDH-1 formulation are described
in Table 5. It should be noted that this chemical product is a
formulation of several block copolymers (polyethers), each one with
a function as emulsion breaker, coalescer of water droplets in
crude oil or clarifier of the aqueous phase. The fact that the
dehydrating FDH-1 formulation consists of several polyethers
(dehydrating basics), makes it more expensive. In contrast,
acrylic/aminoacrylic copolymers were not formulated, because a
single molecule has the three demulsifying functions (breaker,
coalescer and clarifier), presenting a clear advantage over the
commercial formulation. The integration of the three properties
into a single molecule represents an advantage over the commercial
formulation, since the demulsifying product is prepared in one-step
reaction and a further mixing step is not required.
TABLE-US-00005 TABLE No. 5 Commercial formulation FDH-1
composition, including average molecular mass Mn and composition of
POP/POE wt %. FDH-1 Formulation Label Mn (g/mol) Composition (wt %)
TP 89 7750 90/10 TP 03 5330 70/30 TP 14 3050 60/40 TP 71 1400
90/10
[0084] The assessment procedure is described below: the number of
graduated bottles, provided with inserts and covers, is indicated
by the number of compounds to evaluate, and one more, corresponding
to additive-free crude oil (blank) was included. Crude oil was
added until the mark of 100 mL. All testing bottles were placed in
a water bath with controlled temperature at 80.degree. C. by 20
minutes. At the end of this time, one aliquot of the solution of
every synthesized random copolymer and the commercial product
(FDH-1) was added. All bottles were shaken during 2 minutes, at a
speed of 2 blows per second. After being purged, these bottles were
placed again in the thermalized bath and the breakdown of water in
oil emulsion was read every 5 minutes during the first hour and,
subsequently, every hour, along the evaluation time (5 h). All the
copolymers of this invention and the commercial formulation were
evaluated at different concentrations, in the range between 100 and
2000 ppm.
[0085] The crude oils employed to evaluate as dehydrating agents
the random copolymers, based on alkyl acrylate/aminoalkyl acrylate,
were characterized as follows:
TABLE-US-00006 TABLE No. 6 Physicochemical characterization of
crude oils Parameter Ayin-01 Ayin-04 Ayin-09 .degree. API 38.71
18.77 12.31 Sal content (lb/Mbbl) 14.13 4275.00 2732.00 Wax (wt %)
1.35 3.11 3.90 Pour point (.degree. C.) -27.00 -24.00 -15.00
Distilled water (vol %) 0.10 18.00 25.00 Water and sediments (vol
%) 0.90 21.00 27.00 Kinematic viscosity (mm.sup.2/s) @ 4.87 993.97
2945.15 25.degree. C. Cryoscopy MW (g/mol) 242.50 320.01 415.18
Osmometry MW (g/mol) 466.20 891.14 2132.11 n-heptane insolubles (wt
%) 0.30 12.14 14.78 SARA Analysis Saturates (wt %) 52.71 20.38
20.35 Aromatics (wt %) 36.72 39.32 36.17 Resins (wt %) 9.85 26.71
26.43 Asphaltenes (wt %) 0.69 13.52 16.95
[0086] By way of demonstration, which does not imply any
limitation, the results of the evaluation described above are
reported in FIGS. 1, 2, 4, 5, and 7, whereas images of bottles
after the evaluation are shown in FIGS. 3, 6 and 8.
[0087] The difference between the acrylic/aminoacrylic random
copolymers AK271 and AK271-L, respecting to the synthesis method
employed, by using a batch or a semi-continuous reactor, may be
observed in FIG. 1. It is noted that at 1000 ppm the synthesized
copolymer in semi-continuous reactor removed 100% of water from
evaluated crude oil (12.31.degree. API) in 20 min; whereas its
analogous (synthesized copolymer by batch) reached until 2 h of
evaluation. On the other hand, when the concentration is reduced at
500 ppm, both copolymers showed a water removal rate very similar,
but the speed of water coalescence was greater in the sample
synthesized in the semi-continuous reactor, because it reached a
water removal of 95% at 2 h of evaluation, whereas the another one
reached this value after 4 h of evaluation. In this FIG. 1 is
observed that the blank cannot remove water, which indicates that
the water/oil emulsion is colloidally stable.
[0088] Once observed that semicontinuous emulsion polymerization
allows obtaining acrylic/aminoacrylic copolymers more efficient, in
FIG. 2 is compared the AK271 copolymer with the commercial product
FDH-1, at a concentration of 1000 ppm. It is important to remember
that the FDH-1 formulation, widely used in the oil field, consists
of the combination of four polyethers with various dehydrating
properties. After the evaluation was carried out, it was observed
that the acrylic/aminoacrylic copolymer was able to remove 100% of
dispersed water in only 20 min, whereas commercial formulation
FDH-1, based on conventional polyethers, just removed all the water
after 2 h This results imply that the copolymer of this invention
is more effective in a 60% compared to the commercial formulation
at the same conditions. When products were dosed at 500 ppm, it was
determined that the performance of random copolymers decreases,
because it reached the 100% until 2 h of evaluation. However, the
commercial product could not remove more than 20% of water
throughout the evaluation. When commercial formulation FDH-1 is
dosed at twice of concentration (1000 ppm), it behaved similar to
copolymer at concentration of 500 ppm, both evaluated in crude oil
of 12.31.degree. API. In any case was noted spontaneous water
removal from blank. In this way, the best performance of basis
dehydrator of type acrylic is demonstrated, which combines in a
single molecule the properties of a demulsifier (breakdown,
coalescence and clarification of water phase).
[0089] Two phenomena may be observed in FIG. 3: firstly, the
difference of water removal induced by the two products, being
AK272 at 1000 ppm able to remove very fast 100 vol % of water from
Ayin-09 crude oil (12.31.degree. API); secondly and much more
notorious, there is a remarkable difference between the quality of
the removed water, which means that a greater clarification is
observed in the bottle dosed with the acrylic/aminoacrylic
copolymer. In contrast, when the, FDH-1 formulation is applied
there is no a total cleaning of the removed aqueous phase.
[0090] The dependence between the removal of water from crude oil
of 12.31.degree. API and the composition of a series of different
acrylic/aminoacrylic random copolymers dosed at 1000 ppm is shown
in FIG. 4. Regarding to AK281 copolymer, with 80 wt % of A-acrylic
monomer and 20 wt % of aminoacrylic monomer, this compound
displayed the best performance as dehydrating agent, removing 100%
of water from crude oil at just 15 min: Its efficiency was followed
by that of AK271 copolymer, with composition of A/K2 70/30 wt/wt;
this copolymer removed all the water after 20 min of the
evaluation. An intermediate behavior between the two samples early
described is that of AK261 demulsifier, which has an intermediate
coalescence rate between AK281 and AK271 copolymers, removing 100%
of water at the first hour of evaluation. On the other hand,
commercial product FDH-1 fails to reach 100% of water removal in
less time than the copolymers mentioned above. AK291 copolymer,
with the lowest composition of aminoalkyl acrylate (A/K2: 90/10
wt/wt), did not show good performance as dehydrating agent, barely
removing 10% of water from evaluated crude oil. Therefore, there is
an optimal chemical composition to carry out the dehydrating of
crude oils, which would correspond to that of AK281 (A/K2: 80/20
wt/wt). Blank allowed validating the assessment, showing the high
stability of water-in-oil emulsion throughout the evaluation. In
spite of the stability of water-in-oil emulsion, AK281
acrylic-aminoacrylic copolymer, with a suitable composition and
molecular mass, achieved a better water removal than the most
commonly used polyether formulation.
[0091] In FIG. 5 could observe the effect that has the molecular
mass of acrylic/aminoacrylic random copolymers over their
performance as dehydrating agents, at a concentration of 500 ppm,
in crude oil of 18.77.degree. API (Ayin-04). Again, the blank
allowed validating the test, showing that there is no removal of
water induced by lack of colloidal stability during the test. It
was observed that there is an optimal molecular weight for
demulsifier copolymers, which corresponds to AK372 copolymer (15430
g/mol), which reached 100% of water removal at 90 min of
evaluation; meanwhile, AK371 (24312 g/mol) and AK373 (12160 g/mol)
converged at same time to remove 90 vol % of water from crude oil
at 4 h of evaluation. These copolymers outperformed the commercial
product FDH-1, formulation of commercial raw materials that reached
to remove approximately 25 vol % of water.
[0092] In FIG. 6 shows that both products removed the same amount
of water from Ayin-04 crude oil (18.77.degree. API). Moreover, it
is notable the marked difference in clarification of water removed
in the crude oil by the chemical products evaluated, because it is
observed in Figure (6) the bottle dosed with the
acrylic/aminoacrylic copolymer (AK272) that adequately cleans the
aqueous phase, whereas in the case of the FDH-1 formulation, there
is no a marked clarification of water removed.
[0093] FIG. 7 shows the effect by changing the type of alkyl
acrylate on the copolymers, replacing A for B; likewise, it shows
the effect that exists regarding molecular weight over the
efficiency as dehydrating agents in light crude oil of
38.71.degree. API (Ayin-01). A similar behavior similar to that
reported in FIG. 4 was observed, because the BK172 sample is the
one with the best performance as dehydrating agent, being the only
one capable to remove 100% of water from light crude oil.
Performance of BK-172 copolymer was followed by BK-171 and BK-173,
which show a similar behavior and only removed 90 vol % of water.
Finally, the formulation of commercial products FDH-1 and BK-174
copolymer revealed a similar performance, removing around 50% of
water dispersed in the crude oil. There was no water removal from
the blank.
[0094] The difference between copolymers base on alkyl
acrylate/aminoalkyl acrylate and commercial product FDH-01 is
observed again in FIGS. 8(a) and (b). Even if the chemical
composition of a mined product BK172 is changed, this demulsifier
keeps its property as good clarifier of the water removed from
Ayin-01 crude oil (38.71.degree. API). In contrast, FDH-01 product
does not clarify adequately the aqueous phase removed from crude
oil. Again, the best performance of acrylic-aminoacrylic copolymers
of controlled molecular mass is observed in light crude oil with
respect to the properties of commercial demulsifiers commercially
available.
* * * * *