RU2601355C1 - Composition for inhibiting formation of hydrates in hydrocarbon-containing raw material - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to compositions for inhibiting formation of gas hydrates in different hydrocarbon-containing liquids and gases containing hydrate-forming agents and water, and can be used in processes of extraction, processing and transportation of hydrocarbon raw material to prevent formation of gas hydrates. Composition contains a kinetic inhibitor, thermodynamic inhibitor and synergetic additive selected from a group comprising quaternary ammonium salts, ethylene glycol esters of general formula R₁OCH₂CH₂OR₂, where R₁ is a hydrogen atom or alkyl radical, R₂ is an alkyl radical, oxyethylated fatty alcohols, oxypropylated fatty alcohols, polyethylene oxide, polypropylene oxide, copolymers of ethylene oxide and propylene oxide or a mixture of said substances in following ratio of components, wt%: kinetic hydrate formation inhibitor 2.0-8.0; thermodynamic hydrate formation inhibitor 84.0-96.0; synergetic additive - balance.

EFFECT: higher inhibiting capacity.

1 cl, 4 ex

Description

The invention relates to compositions for inhibiting the formation of gas hydrates in various hydrocarbon-containing liquids and gases containing water and hydrate-forming agents, and can be used in the processes of production, processing and transportation of hydrocarbon raw materials to prevent the formation of gas hydrates.

The formation of gas hydrates in field equipment and pipelines is one of the most important technological problems that occurs during the extraction, transportation and processing of liquid and gaseous hydrocarbon feedstocks.

In natural gas, gas condensate, oil, there are compounds (CH ₄ , C ₂ H ₆ , C ₃ H ₈ , iso-C ₄ H ₁₀ , n-C ₄ H ₁₀ , CO ₂ , H ₂ S), under certain thermobaric conditions in the presence of water, forming gas hydrates, which, being solid crystalline substances, are deposited on the walls of pipes and equipment, which leads to a sharp decrease in the throughput of production wells and technological pipelines until they are completely blocked. The formation of gas hydrate plugs can lead to a halt in the processes of production, transportation, processing of hydrocarbon raw materials and, as a result, to significant financial losses.

It is known to use a thermodynamic hydrate inhibitor (TIG), in particular alcohol (RU 2049957, 1998) as a composition for inhibiting gas hydrates in a hydrocarbon-containing feed.

However, due to the high working concentrations of thermodynamic inhibitors (up to 60% wt ..), the use of such a composition is associated with high costs and environmental problems.

It is known to use a kinetic inhibitor of hydrate formation (KIG) as a composition for inhibiting hydrate formation in hydrocarbon-containing raw materials (RU 2126513, 1999, RU 2134678, 1999, RU 2137740, 1999). Such reagents, without affecting the thermodynamics, significantly affect the kinetics of the hydrate formation process, increasing the induction period of this process. The main advantages of kinetic hydrate inhibitors, which are, as a rule, water-soluble polymers, are their low working concentrations (0.3-1% wt ..) and low toxicity. The main disadvantage of CIG is that they cannot be used in cold climates at temperatures below 0 ° C, since low working concentrations do not provide a significant depression in the freezing temperature of water. An approach related to the use of combined reagents combining the advantages of kinetic hydrate formation inhibitors and antifreeze substances is promising for such conditions.

A composition for inhibiting gas hydrates in a hydrocarbon-containing feed is known, which contains at least one kinetic inhibitor of hydrate formation and at least one thermodynamic inhibitor of hydrate formation (CA 2506925, 2006).

Moreover, the kinetic inhibitor of hydrate formation, in particular, includes aminated polyalkylene glycols represented by the formula R ₁ R ₂ N [(A) a- (B) b- (A) c- (CH ₂ ) d-CH (R) -NR ₁ ] nR ₂ (I) in which: - each A is independently selected from —CH ₂ CH (CH ₃ ) O— or —CH (CH ₃ ) CH ₂ O—; B is —CH ₂ CH ₂ O—; a + b + c is from 1 to about 100; R is —H or —CH ₃ ; - each R ₁ and R _{2 are} independently selected from the group consisting of —H, —CH ₃ , —H ₂ CH ₂ OH, and —CH (CH ₃ ) CH ₂ O; d is from 1 to about 6; n is from 1 to about 4.

The disadvantages of this composition are the high corrosion activity of the used TIGs (electrolyte salts), the complexity of the synthesis of CIG, the high consumption of polymer CIG, the relatively low maximum degree of supercooling and the insufficient induction period of hydration.

Closer to the invention is the composition used in carrying out the method of inhibiting the formation of hydrates of hydrocarbons, including the injection of this composition into the borehole zone or section of the pipeline. The specified composition contains an aqueous solution of a polymer from the group including: a copolymer of pyrrolidone or caprolactam, a terpolymer based on N-vinyl-2-pyrrolidone, dimethylaminoethyl methacrylate, hydroxyethyl cellulose, polyvinylpyrrolidone, polyvinylcaripanamyl acrylamide a group including: polyacrylamide, carboxymethyl cellulose, hydroxyethyl cellulose ether, polymethacrylate, polyvinyl acetate or polyvinyl alcohol or copolymers thereof, and tively - urea-formaldehyde concentrate and a CPK hydrophobizing additive in the following ratio, wt. %: the specified aqueous solution or emulsion 0.05-5.0, KFK 0.1-5.0, water-repellent additive 0.1-5.0, the rest is water. In this case, before injection of the specified composition, the KFK rim is additionally pumped in an amount of 0.1-5.0 wt. % by weight of the specified composition and carry out exposure for at least 3-5 hours. Additionally, the specified composition may contain hydrochloric or acetic acid, or a mixture of them, or a mixture of hydrochloric acid and a low molecular weight acid concentrate, or phosphoric or phosphoric acid in an amount of 0.05 -0.20 wt. % (RU 2504642, 2014).

The disadvantages of this composition are that when hydrate formation is inhibited, it does not provide a sufficient degree of decrease (depression) in the crystallization temperature of ice, which does not allow the use of this composition at temperatures below 0 ° C, nor does it provide the necessary degree of supercooling during hydrate formation. In addition, the use of this composition leads to insufficiently high induction period of hydrate formation.

Thus, the known composition is not effective enough.

The objective of the invention is to increase the effectiveness of the composition for inhibiting the formation of hydrates in hydrocarbon-containing raw materials.

The problem is achieved by the described composition of the inhibition of hydrate formation in hydrocarbon-containing raw materials, including water and hydrate-forming components, containing a kinetic inhibitor of hydrate formation, a thermodynamic inhibitor of hydrate formation and a synergistic additive selected from the group comprising quaternary ammonium salts, ethylene glycol ethers of the general formula R ₂ O ₂ CH _{2 2,} wherein R ₁ - hydrogen atom or an alkyl radical, a R ₂ - alkyl radical, ethoxylated fatty alcohols, propoxylated fatty Peart, polyethylene oxide, polypropylene oxide, copolymers of ethylene oxide and propylene oxide or mixtures of these substances in the following ratio,% wt .:

kinetic hydrate inhibitor 2.0-8.0 thermodynamic hydrate inhibitor 84.0-96.0 synergistic supplement the rest is up to 100

The technical result achieved is a higher, in comparison with the known composition, inhibitory ability of the described composition.

Thus, the described composition can be used to inhibit the formation of gas hydrates at a degree of subcooling up to 30 ° C with an induction period of 40 hours or more, including at low temperatures <0 ° C (the known method provides inhibition at higher temperatures at a degree hypothermia no higher than 12.6 ° C with an induction period in the range of 17-36.8 hours). The components used in the composition inhibit the initial formation (nucleation) of gas hydrates, slow down the formation or growth of hydrate crystals, and prevent agglomeration of smaller hydrate crystals into larger ones.

As a hydrocarbon-containing raw material, it is possible to use such as, for example, oil-based water-containing emulsions, said emulsions containing a hydrocarbon gas, gas condensate, raw materials containing a hydrate-forming gas, water, as well as other hydrocarbon-containing raw materials containing water and hydrate-forming components, characteristic, in particular , for the processes of production, processing and transportation of hydrocarbons.

The described composition is introduced into the feedstock in an amount of 2.5 -50.0% wt. from water contained in the specified raw materials. Entering the composition in the specified amount into hydrocarbon feedstock, including water and hydrate-forming components, provides the optimal content of the composition and water components, comprising: kinetic hydrate inhibitor 0.1-2.0% wt., Thermodynamic hydrate inhibitor 5.0-40.0% wt., synergistic additive of 0.1-2.0% wt., water - the rest, up to 100% wt. The specific ratio is determined by the nature of the components of the composition and thermobaric conditions at the oil and gas facility.

In the described composition, in order to inhibit the formation of hydrates, water-soluble polymers, such as, in particular, poly-N-vinyl lactams, substituted polyacrylamides, hyperbranched polyetheramides, polyvinyl alcohol and its derivatives and other high molecular weight compounds with the properties of KIG, are used as a kinetic inhibitor of hydrate formation. As a thermodynamic hydrate inhibitor, it is possible to use, in particular, methanol, ethanol, mono-, di-, triethylene glycol, propylene glycol, glycerin, low molecular weight ethers of mono-, di- and triethylene glycol, propylene glycol, urea or a mixture thereof. As a synergetic additive used quaternary ammonium salts (e.g., tetrabutylammonium halides, cetyltrimethylammonium halides, halides tsetildimetilammoniya halides dodecyldimethylammonium halides didodecyldimethylammonium), mono- and dialkyl ethers of ethylene glycol of the general formula R ₁ OCH ₂ CH ₂ OR ₂ where R ₁ - hydrogen or an alkyl radical, in particular the number of carbon atoms greater than 3, a R ₂ - alkyl radical, in particular the number of carbon atoms greater than 3 (e.g., ethylene glycol monobutyl ether, dibutyl ethylene glycol ester), ethoxylated fatty alcohols (e.g. Syntanol ALM-10, Surfynol 485), hydroxypropylated fatty alcohols, polyethylene oxide (with a molecular oh, in particular 200-8000), polypropylene oxide (with a molecular weight, in particular 200-8000 ), copolymers of ethylene oxide and propylene oxide (for example, with an average molecular weight of 5000) or a mixture of these substances.

The use of such a combined composition can enhance the advantages of these classes of inhibitors and, as a result, increase the efficiency of inhibition of hydrate formation. On the one hand, the use of antihydrate reagents can significantly reduce the consumption of a thermodynamic hydrate inhibitor. On the other hand, the used anti-hydrate reagents can be used to form hydrates in technological processes at temperatures <0 ° C due to the fact that the thermodynamic inhibitor included in the composition is simultaneously an antifreeze substance and therefore significantly lowers the crystallization temperature of ice. The prevention of ice formation along with the inhibition of hydrate formation is a prerequisite limiting the range of inhibitors used at low temperatures. The use of a kinetic inhibitor without the use of other components is ineffective at temperatures <0 ° C, since due to low working concentrations the latter does not provide a significant depression in the temperature of ice crystallization. The presence in the composition of a synergistic additive in the indicated amounts predetermines an increase in its inhibitory ability, allows to reduce the concentration and, consequently, the consumption of expensive polymer CIG. In addition, the presence of surface-active compounds (quaternary ammonium salts, mono-, di- and triethylene glycol ethers, hydroxyethylated and hydroxypropylated fatty alcohols, copolymers of ethylene oxide and propylene oxide) gives the described composition anti-agglomerate properties.

The described composition for inhibiting the formation of hydrates is prepared as follows.

The above composition is prepared by mixing the calculated amounts of the components in a separate container. To obtain the composition used, the kinetic inhibitor of hydrate formation is dissolved in a thermodynamic inhibitor of hydrate formation at a temperature of 20-30 ° C with vigorous stirring. Then, a synergistic additive is added to the mixture with stirring. The finished composition is introduced into a hydrocarbon-containing raw material containing water and hydrate-forming components in various ways, in particular directly into the raw material, and pumped into the near-well zone or into the pipeline section.

The invention is illustrated by the following examples, not limiting its use.

Application of the composition illustrated in the example of use as starting hydrocarbonaceous feedstock model mixture consisting of the gas mixture 95,66% CH ₄ + 4,34% C ₃ H ₈ and water.

Example 1

To prepare the described composition, as a kinetic inhibitor of hydrate formation, a copolymer of N-vinylcaprolactam and N-vinylpyrrolidone (1: 1 unit ratio, weight average molecular weight of 3000) is used in an amount of 2.5% by weight, and monoethylene glycol in an amount of 94% as a thermodynamic inhibitor of hydration wt., as a synergistic additive - monobutyl ether of ethylene glycol in an amount of 3.5% wt. In this case, the kinetic inhibitor is dissolved in monoethylene glycol and stirred at a temperature of 20-30 ° C until smooth. Ethylene glycol monobutyl ether is added to the resulting solution and mixed again until smooth.

The amount of composition added to the feed is 27% by weight of the water contained in the feed. After adding the composition, the resulting mixture is stirred on a magnetic stirrer until the composition is completely dissolved. The resulting aqueous solution has an ice crystallization temperature of minus 8 ° C. 250 cm ^{3 of the} resulting solution is placed in an autoclave with a volume of 500 cm ³ . The free volume of the autoclave is purged with the original gas mixture in order to remove air. After purging, a gas mixture is supplied to the autoclave to a pressure of 4 MPa at room temperature. The contents of the autoclave are mixed with a paddle mixer at a speed of 600 rpm and cooled at a speed of 1 ° C / h. Hydrate formation begins at a temperature of minus 7.7 ° C, which corresponds to a degree of hypothermia of 21.4 ° C (equilibrium temperature of 13.7 ° C for an uninhibited system).

The induction period of hydrate formation is measured as follows. 250 cm ^{3 of the} resulting solution is placed in an autoclave. The free volume of the autoclave is purged with hydrate-forming gas to remove air. The contents of the autoclave with stirring at a speed of 600 rpm are cooled to minus 3 ° C and thermostated. The gas mixture is fed into the autoclave to a pressure of 3.58 MPa. The hydrate formation process begins 38.6 hours after the hydrate forming gas is supplied. Thus, the induction period is 38.6 hours.

Example 2

To prepare the described composition, as a kinetic inhibitor of hydrate formation, a copolymer of N-vinylcaprolactam and N-vinylpyrrolidone (ratio of units 1: 1, weight average molecular weight of 3000) in an amount of 5.0% wt. Is used, as a thermodynamic inhibitor of hydrate formation - methanol in an amount of 90% wt., as a synergistic additive - tetrabutylammonium bromide in an amount of 5.0% wt. In this case, the kinetic inhibitor is dissolved in methanol and stirred at a temperature of 20-30 ° C to a homogeneous mass. Tetrabutylammonium bromide is added to the resulting solution and mixed again until smooth.

The amount of added composition in the feed is 11% wt. from the amount of water contained in the feedstock. After adding the composition, the resulting mixture is stirred on a magnetic stirrer until the composition is completely dissolved. The resulting aqueous solution has an ice crystallization temperature of minus 8 ° C. 250 cm ^{3 of the} resulting solution is placed in an autoclave. The free volume of the autoclave is purged with the original gas mixture in order to remove air. After purging, a gas mixture is supplied to the autoclave to a pressure of 4 MPa at room temperature. The contents of the autoclave are mixed with a paddle mixer at a speed of 600 rpm and cooled at a speed of 1 ° C / h. Hydrate formation begins at a temperature of minus 7.5 ° C, which corresponds to a degree of hypothermia of 21.2 ° C (equilibrium temperature of 13.7 ° C for an uninhibited system).

The induction period of hydrate formation is measured as follows. 250 cm ^{3 of the} resulting solution is placed in an autoclave. The free volume of the autoclave is purged with hydrate-forming gas to remove air. The contents of the autoclave with stirring at a speed of 600 rpm are cooled to minus 3 ° C and thermostated. The gas mixture is fed into the autoclave to a pressure of 3.58 MPa. The hydrate formation process begins 37.1 hours after the hydrate forming gas is supplied. Thus, the induction period is 37.1 hours.

Example 3

To prepare the described composition, poly (N-vinylcaprolactam) (weight average molecular weight 3000) in the amount of 8.0 wt.% Is used as a kinetic inhibitor of hydrate formation, ethanol in the amount of 84 wt.% As a thermodynamic inhibitor of hydrate formation, and as a synergistic additive, ethoxylated fatty alcohol Sintanol ALM-10 4.0% wt. and cetyltrimethylammonium bromide 4% wt. In this case, the kinetic inhibitor is dissolved in ethanol and stirred at a temperature of 20-30 ° C to a homogeneous mass. Syntanol ALM-10, cetyltrimethylammonium bromide are added to the resulting solution and mixed again until smooth.

The amount of added composition in the feed is 8.0% wt. from the amount of water contained in the feedstock. After addition, the resulting mixture was stirred on a magnetic stirrer until the composition was completely dissolved. The resulting aqueous solution has an ice crystallization temperature of minus 4.5 ° C. 250 cm ^{3 of the} resulting solution is placed in an autoclave. The free volume of the autoclave is purged with the original gas mixture in order to remove air. After purging, a gas mixture is supplied to the autoclave to a pressure of 4 MPa at room temperature. The contents of the autoclave are mixed with a paddle mixer at a speed of 600 rpm and cooled at a speed of 1 ° C / h. Hydrate formation begins at a temperature of minus 4.1 ° C, which corresponds to a degree of hypothermia of 18.0 ° C (equilibrium temperature of 13.9 ° C for an uninhibited system).

The induction period of hydrate formation was measured as follows. 250 cm ^{3 of the} resulting solution is placed in an autoclave. The free volume of the autoclave is purged with feedstock to remove air. The contents of the autoclave with stirring at a speed of 600 rpm are cooled to 0 ° C and thermostated. The gas mixture is fed into the autoclave to a pressure of 3.65 MPa. The hydrate formation process begins 40.1 hours after the hydrate forming gas is supplied. Thus, the induction period is 40.1 hours.

Example 4

To prepare the described composition, poly (N-vinylcaprolactam) (weight average molecular weight 3000) in the amount of 4.8% wt. Was used as a kinetic inhibitor of hydrate formation, and methanol in the amount of 90.2% wt. Was used as a thermodynamic inhibitor of hydrate formation, as a synergistic additives - laprol (polypropylene oxide) 5.0% wt. In this case, the kinetic inhibitor is dissolved in methanol and stirred at a temperature of 20-30 ° C to a homogeneous mass. Laprol is added to the resulting solution and mixed again until smooth.

The amount of added composition in raw materials is 26.7% wt. from the amount of water contained in the feedstock. After addition, the resulting mixture was stirred on a magnetic stirrer until the composition was completely dissolved. The resulting aqueous solution has an ice crystallization temperature of minus 19 ° C. 250 cm ^{3 of the} resulting solution is placed in an autoclave. The free volume of the autoclave is purged with the original gas mixture in order to remove air. After purging, a gas mixture is supplied to the autoclave to a pressure of 4 MPa at room temperature. The contents of the autoclave are mixed with a paddle mixer at a speed of 600 rpm and cooled at a speed of 1 ° C / h. Hydrate formation begins at a temperature of minus 15.1 ° C, which corresponds to a degree of hypothermia of 28.5 ° C (equilibrium temperature of 13.4 ° C for an uninhibited system).

The induction period of hydrate formation was measured as follows. 250 cm ^{3 of the} resulting solution is placed in an autoclave. The free volume of the autoclave is purged with feedstock to remove air. The contents of the autoclave with stirring at a speed of 600 rpm are cooled to minus 10 ° C and thermostated. The gas mixture is fed into the autoclave to a pressure of 3.55 MPa. The hydrate formation process begins 45.3 hours after the hydrate-forming gas is supplied. Thus, the induction period is 45.3 hours.

The use of the described composition containing other of the above substances in other concentrations included in the above interval, leads to similar results.

From the above data it follows that the described composition has a higher inhibitory ability than the known one.

Claims (1)

Composition for inhibiting hydrate formation in a hydrocarbon feedstock comprising water and hydrate-forming constituents comprising the kinetic hydrate inhibitors, the thermodynamic hydrate inhibitor and a synergistic additive selected from the group consisting of quaternary ammonium salts, ethylene glycol esters of the general formula R ₁ OCH ₂ CH ₂ OR ₂ where R ₁ is a hydrogen atom or an alkyl radical, R ₂ is an alkyl radical, ethoxylated fatty alcohols, hydroxypropylated fatty alcohols, polyethylene oxide, polypropylene oxide, s polymers of ethylene oxide and propylene oxide or a mixture of these substances in the following ratio, wt.%:
kinetic hydrate inhibitor 2.0-8.0 thermodynamic hydrate inhibitor 84.0-96.0 synergistic supplement the rest is up to 100