RU2392294C1 - Inhibitor of paraffin deposits - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: inhibitor of asphaltresinparaffin deposits is represented by a product of condensation of stearic acid and melamine, the mole ratio being accordingly from 1.0:1.0 to 3.0:1.0 and the inhibitor content in the oil varying from 0.01 to 0.1 wt %. ^ EFFECT: increase of inhibition extent of asphaltresinparaffin deposits. ^ 2 tbl, 3 ex

Description

The invention relates to the field of development and operation of oil fields, complicated by the formation of asphalt-resin-paraffin deposits.

Paraffin scale inhibitors are used to reduce paraffin formation in oil production. Acrylic and methacrylic acid copolymer (DN-1 inhibitor), ethylene vinyl acetate copolymers (VES 501 inhibitor), a condensation product of synthetic fatty acids and triethanolamine (Azolyat-7 inhibitor), block copolymers of hydroxyalkylated ethylene dienes are used as paraffin scale inhibitors. , foreign inhibitors of the company "Nalko" and "Servo-Champion", a foreign inhibitor of XT-48, etc. [Olenev L.M. New domestic paraffin inhibitors. - M .: VNIIOENG, 1990. - 51 p.].

As an inhibitor of asphalt-resin-paraffin deposits, the TyumII-77 inhibitor is also known [Agaev SG, Berezina Z.N., Khalin AN Inhibition of the process of waxing wells and oil pipelines // Oilfield business. - 1996. - No. 5. - S.16-17]. TyumII-77 inhibitor is an ester of synthetic fatty acids of fraction C _21-25 , pentaerythritol and phthalic anhydride [Agayev S.G. and others. Obtaining experimental batches of depressant additives TyumII-77M // Chemistry and technology of fuels and oils, 1994. - No. 9-10. S.10-11].

In terms of the set of features, the DP-65 inhibitor is closest as an inhibitor of asphalt-resin-paraffin deposits to the claimed invention [RF Patent 2326153 C1, 2008.]. The DP-65 inhibitor is an amide of synthetic fatty acids of fraction C _21-25 and polyethylene polyamines [RF Patent 2106395, C10M 149/14, 149/22, 1998]. Amides of synthetic fatty acids and polyethylene polyamines are effective as inhibitors of asphalt-resin-paraffin deposits with their content of 0.01-0.5% of the mass. [RF patent 2326153 C1, 2008].

Amides of synthetic fatty acids and polyethylene polyamines are not sufficiently high inhibitory ability of asphalt-resin-paraffin deposits.

The problem to which the invention is directed, is the development of an inhibitor to prevent the formation of asphalt-resin-paraffin deposits, improving the inhibitory properties of fatty acid amides.

The problem can be solved by achieving a technical result, which consists in increasing the degree of inhibition of asphalt-resin-paraffin deposits.

The specified technical result is achieved by the fact that the inhibitor of asphalt-resin-paraffin deposits for paraffinic oils contains as a fatty acid amide the condensation product of stearic acid and melamine in a molar ratio of 1.0: 1.0 to 3.0: 1.0, respectively, and when its content in oil 0.01-0.1% of the mass.

The inhibitor is a light brown solid with an acid value of 88-112 mg KOH / g.

Example 1. An example of the preparation of amides of stearic acid and melamine. To obtain an inhibitor of asphalt-resin-paraffin deposits, T-18 brand stearic acid was used with the following properties: molecular weight 284; pour point 64.2 ° C; acid number 192.7 mg KOH / g; saponification number 195.1 mg KOH / g; iodine number 11.9 g of iodine / 100 g; mass fraction of unsaponifiable substances 0.48%. Stearic acid corresponded to GOST 6484-96. Used melamine reactive purity with the following properties: molecular weight 126.1; melting point 364 ° C; density at 20 ° C 1571 kg / m ³ .

For the synthesis of amides of stearic acid and melamine in the first stage, technical diethylbenzene was used as an azeotropic solvent, which is a mixture of isomers with a total content of at least 99.8% of the mass. The content of the para-isomer is about 30% by weight, the ortho-isomer is not more than 3.8% by weight, the rest is meta-diethylbenzene. Diethylbenzene corresponded to TU 2414-040-00203772-96. Zinc oxide, used as a reactive purity catalyst with physicochemical properties similar to published data.

Amides of stearic acid and melamine are obtained by condensation in a 50% solution of diethylbenzene at a boiling point of 183 ° C. To ensure the boiling of the reaction mixture, a bath with dried (water-free) diethylene glycol was used. In a reactor equipped with a Dean-Stark trap, 26.2 g (0.09 mol) of stearic acid, 3.8 g (0.03 mol) of melamine, 30 g of diethylbenzene and 0.15 g of zinc oxide (0.5%) are charged mass for loading reagents). The molar ratio of stearic acid to melamine is 3.0: 1.0, which corresponds to a mass ratio of these reagents of 6.9: 1.0. Since the synthesis is heterogeneous due to the insolubility of melamine in diethylbenzene, it is carried out with mechanical stirring for 20 hours. The synthesis is carried out until the reaction water is completely distilled off into a Dean-Stark trap, also filled with diethylbenzene. Then diethylbenzene was completely distilled off, and the condensation reaction was continued in the melt with increasing temperature from 183 to 235 ° С to obtain amides with an acid number of 87 mg KOH / g. The total synthesis time is 20 hours and 35 minutes. The yield of the finished inhibitor minus the precipitate is 28.3 g - 94.3%.

Example 2. For a comparative assessment of the effect of stearic acid on the effectiveness of inhibitors of asphalt-resin-paraffin deposits, a series of amides was synthesized based on polyethylene polyamines (DP-203 and DP-204) and melamine (DP-214, DP-208 and DP-217) at different molar ratios of the starting reagents . The molar ratios of stearic acid and melamine in the syntheses are, respectively, 1.0: 1.0 (DP-214 inhibitor), 2.0: 1.0 (DP-208 inhibitor) and 3.0: 1.0 (DP-217 inhibitor) . Data on the synthesis conditions are shown in table 1.

To assess the effect of stearic acid on the effectiveness of polyethylene polyamine amides as inhibitors of asphalt-resin-paraffin deposits, amides were synthesized by condensation of stearic acid and polyethylene polyamines with a molar ratio of 2.27: 1.0 (DP-203 inhibitor, see table 1) and with a molar ratio of 9.9 : 1.0 (DP-204 inhibitor, see table 1).

Example 3. Evaluation of the effectiveness of the synthesized inhibitors was carried out on a sample of asphalt-resin-paraffin deposits selected from production wells of the Agan oil field. We used the hydrocarbon portion of the asphalt-tar-paraffin deposits obtained from native asphalt-tar-paraffin deposits by extraction with benzene. The hydrocarbon content of the asphalt-resin-paraffin deposits was 71.1% by mass, the rest (28.9% by mass) - mechanical impurities. The density of the hydrocarbon portion of asphalt-resin-paraffin deposits at 90 ° C is 803 kg / m ³ , the melting point is 79 ° C; the content of heavy aromatics is 6.64% by weight, the content of asphalt-resinous substances is 0.92% by weight, the rest is hydrocarbons desorbed by hexane on silica gel. Hydrocarbons desorbed on silica gel with hexane were additionally analyzed for the content of hydrocarbons in them, which formed a complex with urea. The content of the complexed urea was 25.4% by mass, melting point 81.8 ° C, molecular weight 663, density at 90 ° C 813 kg / m ³ . The melting point of the unformed complex with urea is 24.3 ° C, and the molecular weight is 428.

The inhibition of asphalt-resin-paraffin deposits using inhibitors was evaluated at the laboratory facility of the Tyumen State Oil and Gas University, based on the cold rod method [Agaev SG, Berezina ZN, Khalin AN Inhibition of the process of waxing wells and oil pipelines // Oilfield business. - 1996. - No. 5. - S.16-17]. The installation is made of glass, with the exception of the cold rod, which is made of steel 3. The installation provides quick experiments, their reproducibility and selectivity of the deposition of paraffin hydrocarbons.

As a model of oil, a 10% solution of the hydrocarbon portion of the asphalt-resin-paraffin deposits of the Agan oil field in hexane was used. Resin-tar-paraffin deposits well model real conditions. When selecting hexane simulating liquid petroleum hydrocarbons proceed from its _{heated at} reflux temperature t = 68,7 ° C which is the temperature range from the bottom to the mouth for most Western Siberia wells; Water having a boiling point t _boiling point = 100 ° C was used as a hot heat carrier, and ethanol with t _boiling point = 82.4 ° C was used as a cold heat carrier. During the installation, the water was in a boiling state and had a temperature of 100 ° C, and ethyl alcohol had a temperature of 0 ° C. Ethyl alcohol was cooled to zero temperature in a freon refrigerator company "Lauda".

This combination of solvent and coolants ensures the boiling of the oil model in the working space, and therefore, the simulation of the movement of oil, its degassing and diffusion of solid hydrocarbons from the bulk to the surface of the cold rod. The mass ratio of the "hot" coolant: the working mixture, taking into account the design capabilities of the laboratory setup, is taken to be 2.5: 1. Maintaining this ratio unchanged ensures constant heat transfer.

The prepared solution with a certain concentration of asphalt-resin-paraffin deposits and an inhibitor in the solvent is loaded into the interior of the installation. The unit is equipped with refrigerators for condensation of solvent and coolant vapors and is connected by a thin section to a jacket into which the coolant is poured - water. The installation is heated by electric stove. At the moment of boiling of the “asphalt-resin-paraffin deposits in hexane” system, the supply of refrigerant (ethanol) begins, which circulates in the inner space of the cold rod.

After the end of the experiment, the cold rod with the formed layer of deposits is carefully removed from the installation. The precipitate from the rod is partially mechanically and partly due to heat treatment (fusion) is transferred into a small beaker. Minor traces of hexane are removed from the precipitate in a vacuum oven. The amount of precipitate formed is determined by the gravimetric method. Each experiment was carried out three times, the average value of experiments conducted under the same conditions was taken as the result of the experiment.

The inhibition of asphalt-resin-paraffin deposits was carried out on the described installation under the following conditions: temperature of the hot coolant 100 ° C; temperature of a cold working rod 0 ° С. The temperature gradient between the hot and cold walls was 12.5 ° C / mm. The content of the initial asphalt-resin-paraffin deposits in hexane was 10% of the mass. The loading of asphalt-resin-paraffin deposits was 2.18 g, the loading of hexane was 19.62 g. The inhibitor consumption was varied in the range from 0.01 to 0.5% of the mass. to load the starting products (asphalt-resin-paraffin deposits + hexane in total). The degree of inhibition of asphalt-resin-paraffin deposits was estimated by the ratio:

where M _o is the mass of deposits of solid hydrocarbons on a cold rod without an inhibitor;

M _CR - the mass of deposits after the addition of an inhibitor.

Table 2 presents the results of the inhibition of asphalt-tar-paraffin deposits from a 10% model system of asphalt-tar-paraffin deposits in hexane in the presence of an inhibitor of the prototype, i.e. in the presence of a DP-65 inhibitor, as well as in the presence of a series of inhibitors based on polyethylene polyamines and melamine (see table 1).

From the analysis of the data (see table 2) it can be seen that all synthesized inhibitors are characterized by some inhibitory properties. A comparison of the chemical structure of the inhibitors and their inhibitory ability shows that the DP-203 and 204 inhibitors obtained by the condensation of stearic acid and polyethylene polyamines are noticeably inferior in effectiveness to the DP-65 inhibitor. Thus, stearic acid in the form of condensation products with polyethylene polyamines cannot serve as an equivalent substitute for synthetic fatty acids of fraction C _21-25 (DP-65 inhibitor is a condensation product of FFA fraction C _21-25 and polyethylene polyamines).

At the same time, the simultaneous replacement of synthetic C _21-25 fatty acids with stearic acid, and polyethylene polyamines with melamine allows to obtain DP-214, DP-208 and DP-217 inhibitors, which in the range of their content are 0.01-0.1% by weight . characterized by a higher inhibitory ability than the inhibitor DP-65. Explanations for the higher efficacy of the melamine-based inhibitor may be associated with a higher nitrogen content in melamine compared to polyethylene polyamines.

table 2
Inhibition of paraffin deposits using nitrogen-containing inhibitors in a model of asphalt-resin-paraffin deposits of the Agan oil field (10% wt.) In hexane Inhibitor The degree of inhibition of asphalt-resin-paraffin deposits (%) when the content of the inhibitor,% wt. 0.01 0.05 0.1 0.5 DP-65 41.6 38,4 38.9 65.6 DP-203 31.7 40.3 28.8 -24.0 DP-204 12,4 20.1 30.7 40.1 DP-214 44.5 42.9 47.1 45.4 DP-208 45.9 41.0 55.0 43,2 DP-217 44.6 45.0 57.5 65.5

Table 1
Inhibitor Characterization Inhibitor Chemical structure Appearance and physico-chemical properties DP-65 Amides of synthetic fatty acids are the condensation product of synthetic fatty acids of fraction C _21-25 and polyethylene polyamines with a molar ratio of reactants of 3.0: 1.0, respectively.

The active principle of the inhibitor is a light brown solid; acid number 9.4 mg KOH / g; molecular weight 920; melting point 68 ° C;

RCONH {C ₂ H ₄ N [C (O) R]} _n H, here R = C _21-25 DGG-203 Stearic acid amides - a condensation product of stearic acid and polyethylene polyamines with a molar ratio of starting reagents 2.27: 1.0 The inhibitor is dark brown. The inhibitor was obtained at a reaction time of 12 h in a 50% solution of diethylbenzene at its boiling point (180 ° С); 6 h, additional condensation was carried out at a temperature of 240 ° С. The total synthesis time is 18 hours. The acid value is 8.2 mg KOH / g. DP-204 Stearic acid amides are a condensation product of stearic acid and polyethylene polyamines with a molar ratio of starting reagents of 9.9: 1 (mass ratio 20: 1) The inhibitor is dark brown. The inhibitor was obtained by condensation of the starting products in the melt at a reaction time of 18 h, the synthesis temperature was 240 ° C. The inhibitor is purified by extraction in hexane. An extract with an acid number of 160 mg KOH / g was used. DP-214 Stearic acid amides are a condensation product of stearic acid and melamine at a molar ratio of the starting reagents 1: 1 (mass ratio 2.3: 1) DP-208 Stearic acid amides are a condensation product of stearic acid and melamine at a molar ratio of the starting reagents 2: 1 (mass ratio 4.6: 1) The inhibitor is dark brown. The inhibitor was obtained at a reaction time of 20.5 hours in a 50% solution of diethylbenzene at its boiling point (180 ° C). The acid number is 88-112 mg KOH / g. DP-217 Stearic acid amides are a condensation product of stearic acid and melamine at a molar ratio of the starting reagents 3: 1 (mass ratio 6.9: 1)

Claims (1)

An inhibitor of asphalt-resin-paraffin deposits for paraffinic oils, which is a fatty acid amide, characterized in that the condensation product of stearic acid and melamine is used as a fatty acid amide in a molar ratio of 1.0: 1.0 to 3.0: 1.0 and when the inhibitor content in oil is from 0.01 to 0.1 wt.%.