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; these copolymers are combinations of an acrylic and an aminoacrylic monomer and they 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.

Claims

1. A method of dehydrating and demulsifying crude oils having a density of 10 to 40° API using random copolymers based on alkyl acrylate and aminoalkyl acrylate as dehydrating agents of crude oils, said method comprising adding an active composition containing the copolymer to crude oil in an amount to demulsify the crude oil, where the active composition is formulated as a solution comprising organic solvents, and where said random copolymer has the structural formula (2) and a molecular weight 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=H (hydrogen), CH.sub.3 (methyl); R.sup.2=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), or C.sub.5H.sub.11O.sub.2 (2-(2-methoxyethoxy)ethyl), the aliphatic chain may contain heteroatoms of the ether group, or aromatic rings or rings with heteroatoms of the ether type; R.sup.4=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-dimethyl amino), (CH.sub.2CH.sub.2N(CH.sub.3).sub.2) 2-(dim ethyl amino)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, or (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 method of dehydrating crude oils using random copolymers based on alkyl acrylates and aminoalkyl acrylates, as dehydrating agents of crude oils, according to claim 1, where the organic solvents in the active composition have a boiling point between 35 and 200° C.

3. The method of dehydrating crude oils using random copolymers based on alkyl acrylate and aminoalkyl acrylate, as dehydrating agents of crude oils, according to claim 1, where the organic solvents for formulation are selected from the group consisting of dichloromethane, methanol, ethanol, isopropanol, chloroform, benzene and its derivatives, toluene, xylene, turbosine and naphtha, and mixtures thereof.

4. The method of dehydrating crude oils using random copolymers, based on alkyl acrylates and aminoalkyl acrylates, as dehydrating agents of crude oils, according to claim 1, where the active composition comprises between 10 and 50 wt % of said copolymers.

5. The method of dehydrating crude oils using random copolymers based on alkyl acrylate and aminoalkyl acrylate as dehydrating agents of crude oils, according to claim 4, where the active composition is added to said crude oil at a concentration in a range of between 10 to 2000 ppm based on the amount of said crude oil.

6. The method of dehydrating crude oil and demulsifying crude oil according to claim 1, wherein R.sup.1 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, 2-methoxyethyl, and 2-(2-methoxyethoxy)ethyl.

7. The method of dehydrating and demulsifying crude oil according to claim 1, wherein R.sup.1 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.

8. The method of dehydrating and demulsifying crude oil of claim 1, wherein R.sup.1 is hydrogen, R.sup.1 is n-butyl, R.sup.3 is hydrogen, and R.sup.4 is 2-ethylamino.

9. The method of dehydrating and demulsifying crude oil of claim 1, wherein R.sup.1 is hydrogen, R.sup.1 is hydrogen, R.sup.3 is hydrogen, and R.sup.4 is 2-(dimethylamino) ethyl.

10. The method of dehydrating and demulsifying crude oil of claim 1, wherein R.sup.1 is hydrogen, R.sup.1 is n-hexyl, R.sup.3 is hydrogen, and R.sup.4 is 3-aminopropyl.

11. The method of dehydrating crude oil according to claim 1, wherein R.sup.4 is selected from the group consisting of methylamine, 2-ethylamine, 3-propylamine, 2-dimethylamino, and N-ethylmorpholine.

12. The method of dehydrating crude oil according to claim 6, 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.

13. A method of dehydrating and demulsifying crude oils having a density of 10 to 40° API using random copolymers based on alkyl acrylate and aminoalkyl acrylate as dehydrating agents of crude oils, said method comprising adding an active composition containing the copolymer to crude oil in an amount to demulsify the crude oil, where the active composition is formulated as a solution comprising organic solvents, and where said random copolymer has 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=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.

14. The method of dehydrating crude oil according to 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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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° API. Subsequently, the results of the assessment of a second series of acrylic-amino acrylic copolymers applied in heavy crude oil of 18.77° 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° API is described in FIG. 5.

(2) In Figure No. 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° 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.

(3) Figure No. 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° 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).

(4) In Figure No. 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° API) and b) bottle dosed with the AK272 acrylic/amino acrylic copolymer, at 1000 ppm, in the Ayin-09 crude oil (12.31° API).

(5) Figure No. 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° API at concentration of 1000 ppm; all products are compared with untreated crude oil without treatment (blank).

(6) Figure No. 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° 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).

(7) In Figure No. 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° API) and b) testing bottle dosed with the AK272 acrylic/amino acrylic copolymer, at 500 ppm, in the Ayin-9 crude oil (18.77° API).

(8) In Figure No. 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° 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.

(9) Images included in Figure No. 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° API) and b) Testing bottle dosed with the BK172 acrylic/amino acrylic copolymer, at 100 ppm, in the Ayin-01 crude oil (38.71° API).

DETAILED DESCRIPTION OF THE INVENTION

(10) 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° API.

(11) 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:

(12) 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 338861 B [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° 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° API, employing solvents whose boiling point falls within the range of temperature between 35 to 200° 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 %.

(13) 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:

(14) ##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 R3=H (hydrogen), CH.sub.3 (methyl);
R.sup.2=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=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 (diethylamino)ethyl, (CH.sub.2CH.sub.2CH.sub.2N(CH.sub.3).sub.2) 3-(dimethylamino)propyl, (C.sub.6H.sub.12NO) N-ethylmorpholine.

(15) Wherein, additionally:

(16) x=is a number from 2 to 900.

(17) y=is a number from 2 to 900.

(18) “x” and “y” can be random sequences.

(19) Average number molecular masses are comprised in the ranges from 1000 to 180 000 g/mol.

(20) 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.

(21) 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° API, at concentrations between 10 and 2000 ppm, in order to induce the demulsification of aforementioned crude oils.

(22) 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:

(23) 1.—Size exclusion chromatography (SEC), in a size exclusion chromatograph Agilent® model 1100, with PLgel column and using tetrahydrofuran (THF) as eluent, to calculate the copolymer molecular mass distribution and polydispersity index (I).

(24) 2.—Fourier Transform Infrared spectroscopy (FTIR), in a FTIR spectrometer model Thermo Nicolet® AVATAR, 330 using the method of film technique with OMNIC® software, version 7.0.

(25) 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:

(26) 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:

(27) 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.. Copolymer Weigth ratio (wt %) Synthesis method Mn (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

(28) The results of the synthesis of a series of alkyl polyacrylates (RC 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:

(29) 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

(30) The results of a series of alkyl polyacrylates (RC 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:

(31) 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. Copolymer Weigth ratio (wt %) Synthesis method Mn (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

(32) 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° API. These examples should not be regarded as limiting of what is claimed here.

Series AK

(33) Random copolymer based on alkyl acrylate/alkylamino acrylate, I.R. ν cm.sup.−1: 3395, 2959, 2938, 2873, 1732, 1589, 1457, 1380, 1251, 1164, 1098, 1066, 941, 738.

Series BK

(34) Random copolymer based on alkyl acrylate/alkylamino acrylate, I.R. ν cm.sup.−1: 3446, 2959, 2934, 2873, 1732, 1455, 1379, 1252, 1163, 1117, 1065, 942, 840.

(35) Evaluation of random copolymers based on alkyl acrylate and alkylamino acrylate as dehydrating agents of crude oils with densities between 10 and 40° API.

(36) 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° 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.

(37) 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.

(38) 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

(39) 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° 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.

(40) The crude oils employed to evaluate as dehydrating agents the random copolymers, based on alkyl acrylate/aminoalkyl acrylate, were characterized as follows:

(41) TABLE-US-00006 TABLE NO. 6 Physicochemical characterization of crude oils Parameter Ayin-01 Ayin-04 Ayin-09 ° 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 (° 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) @ 25° C. 4.87 993.97 2945.15 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

(42) 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.

(43) 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° 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.

(44) Once observed that semicontin ous 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° 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).

(45) 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° 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.

(46) The dependence between the removal of water from crude oil of 12.31° 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.

(47) 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° 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.

(48) In FIG. 6 shows that both products removed the same amount of water from Ayin-04 crude oil (18.77° 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 FIG. (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.

(49) 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° 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.

(50) 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 amined product BK172 is changed, this demulsifier keeps its property as good clarifier of the water removed from Ayin-01 crude oil (38.71° 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.