JP2000356088A - Method for preventing closure of pipeline by gas hydrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling formation of a gas hydrate and closure of a pipeline by adding an additive of low concentration to a liquid which forms the gas hydrate. SOLUTION: An amide compound with a molecular weight of less than 1000 is added in a low concentration to a system which can form a clathrate hydrate, the amide compound containing more than one or two of the chemical group (1), wherein R1 and R2 are each independently selected from the group consisting of organic components containing hydrogen and one to five carbon atoms; the total of carbon numbers of R1 and R2 is 7 or less; R1 and R2 may be coupled to each other to form a ring of five to seven members; and the ring may contain O, N, S, P or Si atom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for inhibiting the formation, agglomeration and blockage of gas hydrate in pipes containing oil and / or gas. The present invention relates to both mining and production of oil and gas.

[0002]

2. Description of the Related Art Gas hydrate is a clathrate (inclusion compound) in which small molecules are incorporated into the crystal lattice of water molecules. In the petroleum industry, natural gas and petroleum contain various small molecules that can form gas hydrates, and include hydrocarbons such as methane, ethane, propane and isobutane in addition to nitrogen, carbon dioxide and hydrogen sulfide. sell. Larger hydrocarbons, such as n-butane, neopentane, ethylene, cyclopentane, cyclohexane, benzene, are also hydrate forming components. When these hydrate-forming molecules coexist with water under high pressure and low temperature, the mixture has a tendency to form gas hydrate crystals. For example, ethane forms a gas hydrate only at a temperature of 4 ° C. or less under a pressure of 1 MPa and a pressure of 3MPa.
Under a, gas hydrate is formed only at a temperature of 14 ° C. or lower. These pressures and temperatures are typical working environments when liquid petroleum is produced and transported.

[0003] If gas hydrate is formed in a pipe used to transport natural gas and / or other liquid petroleum, the gas hydrate can eventually block the pipe. Blockage of pipes by hydrate
This could result in production shutdowns and, consequently, severe financial losses. The petroleum and gas industries have used various methods to prevent pipeline hydration blockage. Examples include a method of heating the pipe, a method of reducing the pressure, a method of removing water, and a method of adding an antifreeze that acts as a freezing point depressant such as methanol or ethylene glycol. All of these methods are costly to implement and maintain. The most commonly used method today is to add antifreeze. However, in order for the antifreeze to work effectively, it is necessary to add the antifreeze at a concentration as high as usually 10 to 40% by mass relative to the weight of the water present. Recovery of the antifreeze is also usually required, which requires costly work. Therefore, oil,
There is a need for an inexpensive alternative to current methods for preventing pipe blockage due to hydrates in gas production and mining.

[0004] As an alternative to the above method, the gas hydrate formation process is controlled by the use of nucleation inhibitors, crystal growth inhibitors and / or compounds which inhibit the agglomeration of the formed hydrate crystals. There is a way. Compounds of this type are widely used in other industrial processes, and the advantage of using the compound to control gas hydrate formation is that the amount of the compound used may be 0.01% in concentration. ~ 2%, which is much lower than antifreeze.

[0005] It is also possible to design compounds that bind preferentially to hydrates rather than to water molecules present in large amounts. The interaction of the designed molecule with the hydrate surface can affect hydrate nucleation and hydrate growth rates, as well as morphology, aggregation and agglomeration propensity.

[0006] N-vinylpyrrolidone (Int.
nt Appl. Publ. WO 93/25798),
N-vinylcaprolactam (Int. Patent A
ppl. Publ. WO 94/12761), N-isopropyl methacrylamide (Int.
Appl. Publ. WO 96/41834), acryloylpyrrolidine (Int. Patent App)
l. Publ. It is known that nucleation and growth of gas hydrate can be suppressed by using a monomer such as WO96 / 08672) in combination with a water-soluble polymer. However, these polymers have a limited range of efficacy, and have a high driving force for hydrate formation, for example, during and after sealing of a multi-layered submarine pipeline under high pressure and low submarine temperature. Not available below. Propulsion is often described using subcooling in the system, the temperature difference between the system temperature and the equilibrium temperature for hydrate formation at system pressure.
More precisely, it can be explained by the potential of the system that forms the gas hydrate. Under extremely propulsive conditions, the water-soluble polymer cannot prevent rapid hydrate formation. Also, once rapid hydrate formation occurs, the hydrate aggregates and the deposits cause blockage. Therefore, different techniques are needed to prevent hydrate blockage. This different technique uses an amphiphilic compound having a polar end group that interacts with the hydrate surface, where the side groups of the water-soluble polymer interact. However, at present polar end groups are directly or indirectly attached to long hydrophobic chains. United States Patent 5,460,728
No. WO 95/17579 discloses an alkylated ammonium compound, an alkylated phosphonium compound, and an alkylated sulfonium compound. The compound used for the alkylation has 4 carbon atoms.
One or more. These compounds have low biodegradability and are toxic to marine organisms. Due to the environmental impact of the additive, its use in offshore oil and gas operations is limited. EP
-A-323307 discloses the use of amphiphilic additives to prevent hydrate agglomeration. The additives disclosed above prevent hydrate agglomeration by the formation of very stable water-in-oil emulsions. The emulsion is expensive to separate in the installed liquid process equipment, and the condensate generated during the sealing of the pipeline does not emulsify, forming a hydrate that blocks the pipeline. You. In EP-A-323 774, non-ionic amphiphilic additives consisting of esters of polyols with substituted or unsubstituted carboxylic acids are mentioned as claims. The above example also prevents hydrate agglomeration by producing a very stable water-in-oil emulsion. In EP-A-323775, non-ionic amphiphilic additives consisting of amide compounds are mentioned as claims, which also form hydrates due to the formation of very stable water-in-oil emulsions. It prevents agglomeration.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for controlling gas hydrate blockage of a pipe by adding a low concentration additive to a liquid capable of forming gas hydrate. And The method comprises:
Prevent pipeline blockage by suppressing hydrate generation itself, reduce the possibility of pipeline blockage by delaying hydrate generation, suppress hydrate agglomeration, and have fluidity The method includes a method of transporting the slurry as a slurry in the medium, a method of delaying hydrate aggregation, and a method of extending a time during which the slurry can be transported as a fluid slurry in the medium.

[0008]

Means for Solving the Problems The present inventors have found a method for inhibiting the formation and agglomeration of gas hydrate in a pipeline under hydrate formation conditions. The new method involves the use of amide compounds as described below. The method of the present invention utilizing the amide compound to inhibit gas hydrate formation and agglomeration overcomes the deficiencies of the prior art. That is, the present invention provides: (1) a method for inhibiting and / or suppressing the formation and / or agglomeration of clathrate hydrate by adding the additive to a system capable of forming clathrate hydrate; Is a chemical group (1):

[0009]

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[0010] (wherein, R _1, R ₂ are those each independently selected from the group consisting of organic compounds containing hydrogen and 1-5 carbon atoms, the R ₁ and R ₂ of the carbon atoms The total is 7 or less, and R ₁ and R ₂ may combine to form a 5- to 7-membered ring, and the ring may contain O, N, S, P, Si Amide compound having a molecular weight of less than 1000 containing one or two or more compounds.

(2) The amide compound is represented by the following chemical formula (2):

[0012]

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(Wherein R ₁ and R ₂ are as defined above;
R is a straight or branched chain containing 6 to 24 carbon atoms;
X is an alkyl or alkenyl group, and X is absent or a linking group containing one or more compounds selected from the group consisting of amides, esters, amines and ammonium. The method according to (1), wherein the method is represented by (1).

(3) The method according to (2), wherein the bonding group X contains a second polar terminal group.

(4) The amide compound has a chemical formula (3):

[0016]

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(Where R, R₁, R_TwoIs as defined above.
L is 1 or 2, m is 0 or 1, n
Is 1 or 2, l + m + n = 3, and M is water
Element, metal atom, ammonia, primary organic amine, secondary
Organic amine or tertiary organic amine, when l is 2
May be different from each other, and when n is 2, one of R
R ₁, R_TwoAnd the other R₁, R_TwoAre different
Good. (1) The method according to (1), wherein
It is.

(5) The amide compound has a chemical formula (4):

[0019]

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(Wherein, l, m, n, R, R ₁ and R _{2 are as} defined above, Y is a bonding group selected from alkylene, and when n is 2, Y is a different group. (1).

(6) The amide compound is represented by the following chemical formula (5):

[0022]

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(Wherein M, R, R ₁ , R ₂ and Y are as defined above, and Z is a bonding group selected from alkylene). It is the method described.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The following chemical groups (1):

[0025]

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[0026] (wherein, R _1, R ₂ are those each independently selected from the group consisting of organic compounds containing hydrogen and 1-5 carbon atoms, the R ₁ and R ₂ of the carbon atoms The total is 7 or less, and R ₁ and R ₂ may combine to form a 5- to 7-membered ring, wherein the ring contains O, N, S, P, Si atoms, By adding a low concentration of the amide additive A containing one or more of the above to a system capable of forming a clathrate hydrate containing hydrocarbons and water, thereby inhibiting the growth, agglomeration, and deposition of gas hydrate. Was revealed.

The additive A can interact with the hydrate crystal surface mainly by one or more alkylamide terminal groups, thereby inhibiting the hydrate crystal growth process. The R group inhibits agglomeration of hydrate crystals by making the crystal surface hydrophobic. The additive A also adheres to the wall of the pipe to a certain extent, thereby reducing the adhesion of hydrate crystals to the wall of the pipe. Further, due to the amphipathic property of the additive A, the additive A is concentrated at the water-hydrocarbon interface where hydrate formation is most active.

Under closed conditions (ie, when the system capable of forming clathrate hydrate is at rest), the liquid capable of forming clathrate hydrate comprises an aqueous layer, an emulsion layer,
Frequent separation into liquid hydrocarbon layers. We have found that hydrate formation is most likely to occur in emulsion layers, i.e. areas where the water-hydrocarbon interface is large. Under hydrate formation conditions, if the emulsion layer is large and the sealing time is long, a considerable amount of solid hydrate may form during sealing. It is easier to reflow the pipeline if there is very little or no hydrate in the pipeline. Therefore, in order to reduce the amount of hydrate formed during the stationary sealing period, it is desirable to inhibit the mixture of the emulsion during the stationary sealing period. It is an example of the present invention that one or more additives B are further added to the additive A during the stationary (closed) state in order to reduce the stability of the emulsion. In general, the additive B is preferably a fatty acid ester or a glycol ester in addition to alcohol, glycol, polyglycol, ketone (for example, methyl butyl ketone), and an aromatic compound (toluene, xylene, etc.). Examples include butyl glycol, known as butyl cellosolve.

The present invention relates to a method for inhibiting and / or reducing the formation and / or agglomeration of clathrate hydrate by adding said additive A to a system capable of forming clathrate hydrate, The additive A has a chemical group (1):

[0030]

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(Wherein R ₁ and R ₂ are the same as defined above).

The additive A has a chemical formula (2):

[0033]

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(Wherein R ₁ and R ₂ are as defined above;
R is a straight or branched chain containing 6 to 24 carbon atoms;
X is an alkyl or alkenyl group, and X is absent or a linking group containing one or more compounds selected from the group consisting of amides, esters (including fatty acid esters and glycol esters), amines and ammonium. ) May be used. The bonding group X of the chemical formula (2) may include a second polar terminal group.

Preferably, R ₁ and R ₂ in additive A are selected from ethyl, isopropyl, tetramethylene, and isobutyl. Preferred examples of R ₁ and R ₂ include R ₁ is an isopropyl group and R ₂ is hydrogen, R ₁ is an isobutyl group and R ₂ is hydrogen, R ₁ is an ethyl group and R ₂ is an ethyl group, and R ₁ and R ₂ are ₂ include those forming Pirorijino 5-membered ring containing a nitrogen atom as tetramethylene.

The additive A may have one or more alkylamide terminal groups. With two or more alkylamide end groups, the interaction with the hydrate surface is stronger than with one end group. For example, as an embodiment of the present invention, chemical formula (3):

[0037]

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Where R, R₁, R_TwoIs as defined above.
L is 1 or 2, m is 0 or 1, n
Is 1 or 2, l + m + n = 3, and M is water
Element, metal atom, ammonia, primary organic amine, secondary
Organic amine or tertiary organic amine, when l is 2
May be different from each other, and when n is 2, one of R
R ₁, R_TwoAnd the other R₁, R_TwoAre different
Good. ) Is preferred from among the additives A having the structure represented by
There is a method using a different type.

Another preferred method is represented by the following chemical formula (6):

[0040]

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(Wherein l, m, n, R, R ₁ , and R ₂ are as defined above), using an additive A having a structure represented by the following formula:

Another preferred method is represented by the following chemical formula (4):

[0043]

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Wherein l, m, n, R, R ₁ and R _{2 are as} defined above, Y is an alkylene, preferably a linking group selected from C _{1 to} C ₄ alkylene, and n is 2 In this case, Y may be a different group.).

Another preferred method is represented by the following chemical formula (5):

[0046]

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(Wherein M, R, R ₁ , R ₂ and Y are as defined above, and Z is an alkylene, preferably a bonding group selected from C _{1 to} C ₄ alkylene). A method using an additive A having a structure is exemplified.

Another preferred method is represented by the following chemical formula (7):

[0049]

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(Wherein, m, n, M, R, R ₁ and R ₂ are as defined above, and m + n = 2). .

Another preferred method is represented by the following chemical formula (8):

[0052]

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Wherein M, R, R ₁ and R ₂ are as defined above, and R ′ is a linear or branched alkyl or alkenyl group containing from 1 to 24 carbon atoms. A method using an additive A having a structure represented by the following formula:

Another preferred method is represented by the following chemical formula (9):

[0055]

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(Wherein M, R, R ₁ and R ₂ are as defined above, and Z ′ is a bonding group selected from alkylene). Is mentioned.

Another preferred method is represented by the chemical formula (1)
0):

[0058]

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(Wherein, R, R ₁ and R ₂ are as defined above, and Y is a linking group selected from alkylene, preferably C ₁ -C ₄ alkylene). The method using additive A is mentioned.

Further, the chemical formula (11):

[0061]

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(Wherein R, R ₁ , R ₂ , and Y are as defined above) using an additive A having a structure represented by the following formula:

Another preferred method is represented by the formula (1)
2):

[0064]

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(Wherein l, m, n, M, R, R ₁ and R ₂ are as defined above, W is a linking group selected from alkylene, alkyleneoxy and polyalkyleneoxy; Is 2, one R, W and the other R,
W may be different. )) Is used.

Another preferred method is represented by the chemical formula (1)
3):

[0067]

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(Where l, m, n, R, R ₁ , R ₂ , W,
Y is as defined above. )) Is used.

Another preferred method is represented by the chemical formula (1)
4):

[0070]

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(Wherein M, R, R ₁ , R ₂ , W, Y and Z are as defined above)
Is used.

The total amount of the additive A of the present invention to be added is generally 0.05 to 5% by mass, preferably 0.1 to 5% by mass, based on the amount of water in the system capable of forming clathrate hydrate. 1 to 0.8% by mass, more preferably 0.1 to 0.
5% by mass. The product can be added as a powder, preferably as a concentrate, in a small stream of hydrocarbons and water.

It is also appropriate to add a polymer of an ethylenically unsaturated N-heterocyclic carbonyl compound to a system capable of forming clathrate hydrate. It is particularly suitable that the polymer is a polymer or copolymer of vinylcaprolactam or vinylpyrrolidine. The polymer may be an acryloylpyrrolidine or N-isopropylacrylamide polymer or copolymer.

It is desirable to add an N-alkylacrylamide polymer or an N, N-dialkylacrylamide polymer to a system capable of forming a clathrate hydrate.

It is appropriate to add a polymer comprising a main chain of a hetero atom and a side chain containing an amide group to a system capable of forming a clathrate hydrate.

The polymer is preferably a polymer derived from a comonomer having 6 to 30 carbon atoms. It is particularly preferred that said comonomer is an alkyl acrylate or an unsaturated hydrocarbon.

The product to be added to the system capable of forming a clathrate hydrate suitably contains an aromatic, ketone, ester (including fatty acid ester and glycol ester), alcohol or glycol solvent.

It is also possible to use two or more of the preferred additives A in combination. For example, a combination of two or more of the additives A having different Rs and two or more of the additives A having different R ₁ and R ₂ can be mentioned.

Further, in order to reduce the formation and stability of an emulsion in a system capable of forming a clathrate hydrate in a stationary (closed) state, one or more additives B are added to the additive A. May be added. Preferably, the additive B is a fatty acid ester, a glycol ester, an alcohol, or a polyglycol. An example is butyl glycol, known as butyl cellosolve. The additive concentration of the additive B is 0.0001 to 2% by mass based on the amount of water in the system capable of forming clathrate hydrate, and the additive B is used as a solvent for the additive A. Can work. It is particularly desirable that the second additive is butyl glycol.

The additive A or the additive A
The mixture of the additive B and the additive B may be used together with another surfactant or polymer that inhibits nucleation of gas hydrate or crystal growth. In the method, first, since the liquid transportation is easy to handle, secondly, the additive A has a higher degree of water removal (in a ratio of water to the total liquid amount) as compared with the case where the additive A is used alone. Since it can be used as it is, it is useful in reducing the amount of hydrate solids in the pipeline. Preferred surfactants are those containing alkyl pyrrolidone. Preferred polymers are vinylpyrrolidone,
Homopolymers, copolymers, terpolymers derived from vinylcaprolactam, amide derivatives of maleic anhydride, isopropylacrylamide or acryloylpyrrolidine. Effective polymers are polyvinylpyrrolidone, polyvinylcaprolactam, vinylpyrrolidone-vinylcaprolactam copolymer, vinylcaprolactam-vinylmethylacetamide copolymer.

Further, the mixture of the compounds according to the present invention comprises 1
Alternatively, it may be used with two or more of the following additives.・ Corrosion inhibitors. It is desirable to add the additive in an amount equivalent to 0.01 to 0.5% by mass based on the mass of the contained water. The additive has a useful effect in applying a hydrophobic coating to the pipeline wall to reduce the tendency of hydrate to adhere. A compound comprising an alkyl quaternary ammonium, wherein at least one of the alkyls attached to the quaternary nitrogen atoms contains 4 or 5 carbon atoms. For example, tetrabutylammonium salt, tetrapentylammonium salt, or dipentyl quaternary ammonium, including those selected from the group consisting of dibutyl quaternary ammonium, tripentyl quaternary ammonium and tributyl quaternary ammonium,
Examples include compounds or surfactants or polymers.
The compound is used in an amount of 0.01 to 0.2 with respect to the mass of water contained.
It is desirable to add an amount equivalent to 5% by mass. A compound containing an alkylamine oxide group, wherein at least one of the alkyl groups attached to the nitrogen atom of the amine oxide group is
Compounds each containing 4 or 5 carbon atoms. For example, tributylamine oxide and tripentylamine oxide are mentioned. It is desirable to add the compound in an amount equivalent to 0.01 to 0.5% by mass with respect to the mass of the contained water. ·solvent. Examples include ester solvents, alcohols, ketones, glycols or polyglycols.
Examples include isopropanol, 1-butanol, 2-butanol, butoxyethanol, 2-butoxypropane-
Includes 2-ol and methyl butyl ketone. The solvent is desirably added in an amount equivalent to 0.05 to 2.0% by mass based on the mass of water contained. ·salt. Desirably a halogen salt. For example, sodium chloride and calcium chloride are mentioned. The salt is desirably added in an amount equivalent to 0.05 to 5.0% by mass based on the mass of the contained water. Note that the salt is desirably sodium chloride.

The present invention also relates to a method for inhibiting the formation and agglomeration of gas hydrates, and to the combined use of the above-mentioned compounds.
The invention also relates to the use of said additive A and said additive B for reducing emulsion stability in emulsions and liquids capable of forming hydrates.

The following examples illustrate the invention.

The description in no way limits the scope of the invention to the examples shown, but rather the scope of the invention is defined by the claims.

[0085]

EXAMPLES (Equipment and Test Method) In order to evaluate the efficacy of the additives of the present invention, the following examples show a high-pressure sapphire cell and an M.P. A. Kellland, T .; M. Svarta
as, L .; A. Dybvik, Proc. SPE An
natural Technical Conference
/ Production Operations an
d Engineering, 1994, pp. 431
The high pressure sapphire cell usage shown at -438 was used.

(Sapphire Cell High Pressure Test Apparatus) FIG. 1 shows a sapphire cell high pressure test apparatus.

The sapphire cell was set in a cooling tank. The sapphire cell consists of a sapphire tube 1 sealed between stainless steel plates. The cell size is
The inner diameter is 20 mm, the height is 100 mm, and the wall thickness is 20 mm. The top plate has a length of 15 mm and the bottom plate has a length of 13 mm, and the total capacity of the cell between the top plate and the bottom plate is 22.2.
8 ml. The sapphire cell includes a stirring device, and the stirring blade 2 is connected to a magnet chamber in a bottom plate via a shaft. The stirring speed can be controlled by the external rotating magnetic field 3 created by the experimental stirring rod. The motor of the stirrer is controllable (independent of the motor load) so as to maintain a constant speed in the range of 0 to 1700 rpm. The control / amplification device can output an external output for reading the torque and the rotation speed, and the stirring speed is measured using a stroboscope.

The sapphire cell has windows 4 separated by 0, 90, 180, and 270 degrees for visual observation.
It is installed in a permeable, separable, double-walled carbonate plastic cylinder 4.
The cell contains a temperature control device 9 in a plastic cylinder.
The temperature is controlled by circulating the water through the heating / cooling unit 8 connected to the heater. The cell system is provided with two temperature sensors 5 and 6 for measuring the temperature inside the cell (gas phase) and the temperature of the water bath. The pressure was measured by a pressure transducer 7 via a tube connection pulled from the cell top. Temperature was measured with an accuracy of ± 0.1 ° C. and pressure was measured with an accuracy of ± 0.2 bar. Video recordings of the experiment were also performed. All data is collected in the logger 10,
Data from the automatic recorder 10 was output to a printer or plotter 11 by a computer 12 with a monitor.

The experimental preparation and cell filling were performed in the same procedure in all experiments. All tests were performed using a freshly prepared salt concentration of 3.6% SSW (Synthetic Sea W).
ater), SNG (Synthetic Nature)
al Gas), clear condensate (conde) in the North Sea
nsate). The water removal rate was usually 18-25% in all cell experiments.

The details of the general test procedure are as follows. 1) The additive to be tested was preferably diffused or dissolved in the SSW to the desired concentration. When diffusion or dissolution was not possible, the additive was added directly into the cell as is. 2) The magnet compartment of the cell was filled with a solution containing the additive to be tested. Thereafter, the magnet chamber was set on the bottom plate of the cell, and a sapphire tube and a cell holder were attached. 3) A desired amount of an aqueous solution containing the dissolved or diffused additive is poured into a cell (upper part of the cell bottom) using a pipette, a top plate is placed, and the cell is placed in a cooling tank (plastic cylinder). Attached. 4) The temperature of the cooling tank was adjusted to a temperature deviated from the hydrate existence region under the pressure conditions used in the experiment by 2 to 3 ° C. 5) Before putting mixed SNG and condensate into the cell,
The cell was purged twice with SNG used in the liquid hydrocarbons capable of forming clathrate hydrate in this experiment. 6) Start data recording and video recording, 700 rpm
Liquid hydrocarbons were injected into the cell to the desired pressure while stirring at. The liquid hydrocarbon was a mixed solution consisting of SNG and condensate. After the temperature and pressure in the cell stabilize,
Stirring was stopped. The apparatus was prepared as described above for testing the additives.

When the cells were prepared as described above, usually two test procedures were performed. The first procedure is 700 rpm
To start the agitation, and at the same time, cool the cell to the set temperature in the hydrate formation region in the set system. Normally, the set temperature was set at about 4 ° C. In performing this procedure, it was found that the temperature range where hydrate formation begins was mainly affected by the hydrate inhibition properties of the additives and statistical fluctuations in the system related to the equipment and test procedures.

The second procedure involves cooling the liquid to the lowest temperature without stirring. Usually, the minimum temperature
About 4 ° C. was used. The cooling time was usually 1-2 hours. When the temperature stabilized, stirring was started. In following the second procedure, it was found that hydrate was hardly detected when cooling for 1-2 hours without stirring, and began to be detected after stirring had begun.

It has also been found that the efficacy of additives designed to inhibit the growth, agglomeration and deposition of gas hydrates depends on the driving force for hydrate formation in the system. That is, the second test procedure is a more demanding test for the effectiveness of the additive, since the hydrate formation driving force when agitation is started is at a maximum. In the first procedure, the hydrate is slowly formed from a temperature higher than the temperature which has been reduced to the maximum (the set temperature), that is, from the stage where the propulsive force is small.

(Experiment) Hydrate agglomeration and deposition inhibition test of Additive A The following experiments were performed at a constant temperature. When the temperature and pressure were once stabilized after the cell was loaded, stirring was stopped. The sealed cell was then cooled to the experimental temperature, so that the pressure dropped to P ₀ (bar). When the temperature and pressure stabilized again, stirring was resumed at 700 rpm.

The experimental results were recorded by plotting temperature, pressure (or total gas consumption; TGC) and torque as a function of time. Examples are shown in Tables 1 and 2.
Shown in Experiments were performed at various initial pressures P ₀ , 3.6-4.2.
The _test was performed at a constant initial temperature T ₀ in ° C. Experiments performed at a temperature of 4.0 ° C. and a pressure of 90 bar corresponded to a sub-cooling of about 14.7 ° C. In addition, temperature 4.0 ° C, pressure 200bar
The experiment performed in Example 1 corresponded to a sub-cooling temperature difference of about 18 ° C.

The water removal rate is about 15 to 20%, and all the condensates are obtained from the Frigg Sea area (North Sea). As shown in the table, samples having different condensities (7 to 9) were used. Was done. As the aqueous phase, SSW containing 3.6% by mass of salt was used except for an experiment in which an asterisk (*) was displayed next to the experiment number. In an experiment with an asterisk label, a 0.5% by mass solution was used. "Initial time" in Tables 1 and 2 shows (average torque value / maximum torque value) for the first 2.5 hours of stirring after startup. Also, in "when stable",
(Average torque value / Maximum torque value) 2.5 hours after the start of stirring. In addition, "when a long time has passed"
(Average torque value / Maximum torque value) about 20 hours after the start of stirring.

Good additives formed a slurry-like hydrate that did not agglomerate or settle in the apparatus and the torque did not increase appreciably throughout the experiment. However,
Since the viscosity of the hydrate slurry is higher than that of a system that can form clathrate hydrate, a certain increase in torque is inevitable. Loose particles (soft particles that can be easily removed by high-speed stirring) settled on the wall surface above the liquid level of the stirring solution several times, but these can be washed off occasionally by increasing the stirring speed for a short time. It is.

The grades A to E are codes for comprehensively evaluating the relative potency of the additives. All of the experiments evaluated as A to D showed better results than the experiment in which no additive was added, and are included in the claims of the present invention. A shows that "the torque level during the test is low and stable, there is almost no adherence of hard massive hydrate on the cell walls and the stirring blades, and the solution is a uniform slurry". B shows that "the torque level is low and stable, but a small amount of small hydrate particles adhere to the cell wall." C indicates that "the torque level is slightly higher, and slightly larger hydrate particles adhere to the cell wall or the stirring blade."
Is shown. D shows "Torque level is very high, large massive hydrate adheres to cell walls or stirring blades". E indicates "the inside of the cell is blocked by a large lump hydrate".

The symbols used in the rightmost three columns of Tables 1 and 2 indicate the following operations and observations.

Lp is a loose particle, wo is 13
Fw is hydration film on sapphire wall, A is agglomerate, Dw is
nwo is the deposit on the sapphire wall that could not be washed off by stirring at 1300 rpm, Dw is the deposit on the sapphire wall, Dst is the deposit on the stirring blade, and hDw is the deposit on the stirring blade.
Strong deposition on the sapphire wall, Vs is a viscous slurry, prs is a residue of hydrate particles on the stirring blade, f is a residue of the hydrate film, + is a large degree,-is a degree. It shows that each is small.

The chemical codes shown in Tables 1 and 2 are as follows:
They show compounds represented by the following chemical formulas (15) to (27), respectively.

Chemical formula (15):

[0103]

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(Where Z = H, R = C ₈ H ₁₇ , O
When TMAA is Z = Na and R = C ₈ H ₁₇ , n-OT
MAA is set to NTMAA when Z = H and R = C ₉ H ₁₉
When Z = H and R = C ₁₀ H ₂₁ , DTMAA is used.
When H and R = C ₁₂ H ₂₅ , the structures of LTMAA are shown. ) Chemical formula (16):

[0105]

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(Where R = C ₈ H ₁₇ , FX-OD
EAA, FX-DDEAA when R = C ₁₀ H ₂₁ ,
When the R = C ₁₂ H ₂₅ respectively the structure of the FX-LDEAA. ) Chemical formula (17):

[0107]

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(This is the structure of FX-LIPAA.) Chemical formula (18):

[0109]

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(This is the structure of FX-LDBAA.) Chemical formula (19):

[0111]

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(Wherein, when R = C ₈ H ₁₇ , FX-AI
The P8, the FX-AIP12 when the R = C ₁₂ H _25, R
= When the C ₁₈ H ₃₇ The structure of FX-AIP18, illustrates respectively. ) Chemical formula (20):

[0113]

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(Where R = C ₈ H ₁₇ , FX-DP
CEOA is FX-DPCEDA when R = C ₁₂ H ₂₅
Respectively show the structures of ) Chemical formula (21):

[0115]

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(This is the structure of FX-DIPDECA. R
Is a hydrocarbon group derived from coconut oil. ) Chemical formula (22):

[0117]

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(Wherein, when R = C ₈ H ₁₇ , FX-AC
The AA-TMO, when the _{R = C 12 H 25 FX-} ACAA
3 shows the structure of TMD. ) Chemical formula (23):

[0119]

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(Where R = C ₈ H ₁₇ , FX-AC
AA-IPO, FX-ACAA when R = C ₁₂ H ₂₅
3 shows the structure of the IPD. ) Chemical formula (24):

[0121]

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(Wherein, when R = C ₈ H ₁₇ , FX-AC
AA-DEO, FX-ACAA when R = C ₁₂ H ₂₅
2 shows the structure of DED. ) Chemical formula (25):

[0123]

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(This is the structure of FX-TMD-TMPA.) Chemical formula (26):

[0125]

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(This is the structure of FX-LDEDPS.) Chemical formula (27):

[0127]

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(The structure is FX-PCPN.) The compound is commercially available or can be prepared by a general synthesis method known to those skilled in the art.

[0129]

[Table 1]

[0130]

[Table 2]

[0131] 2. Emulsion stability test using Additive A and Additive B The experiment used the same sapphire cell device as described above.

It is important to conduct an emulsion stability test using gas components as well as hydrocarbons that are liquid at room temperature. This is because the gas component liquefies under the condition where pressure is applied, and also because the gas component melts into the liquid hydrocarbon and affects the stability of the emulsion.

The test procedure is as follows. 3.2g
Of water was added to the cells in all experiments and Additive A was added to a concentration of 5000 ppm relative to the aqueous phase. Pressure was applied to about 120 bar at room temperature using the mixture of SNG and condensate used in the test. The height of the liquid surface of the water and the liquid hydrocarbon was measured, and the liquid in the cell was stirred at 20 ° C. for 30 minutes. Thereafter, the stirring was stopped, and the time until the emulsion completely separated from the aqueous phase and the liquid hydrocarbon phase (oil phase) was measured. The experiment was repeated using a mixture of additive A and additive B. Table 3 shows the results.

[0134]

[Table 3]

The results showed that when the additive ACAA-IPD or the additive DIPCECA was added, the addition of butyl cellosolve improved the separation rate of the emulsion.

[0136]

The results obtained in the hydrate agglomeration and deposition inhibition test and the emulsion stability test using Additive A and Additive B as described above are described herein. It was unexpected based on the prior art. By using the method of the present invention, gas hydrate formation and agglomeration in the gas and oil transportation pipelines under low temperature and high pressure, resulting in clogging of the pipeline, only by using the compound at a low concentration. Can be inhibited.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a sapphire cell high-pressure test apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sapphire tube 2 Stirring blade 3 External rotating magnetic field 4 Carbonate plastic cylinder 5 Cell internal temperature measurement sensor 6 Water bath temperature sensor 7 Pressure transducer 8 Heating / cooling device 9 Temperature control device 10 Automatic recording device 11 Printer / plotter 12 Computer

Claims (6)

[Claims] 1. A method for inhibiting and / or inhibiting the formation and / or agglomeration of clathrate hydrate by adding an additive to a system capable of forming clathrate hydrate, wherein the additive comprises a chemical group (1): (Wherein R ₁ and R ₂ are each independently selected from the group consisting of hydrogen and organic compounds containing 1 to 5 carbon atoms, and the total number of carbon atoms of R ₁ and R ₂ is 7 R ₁ and R ₂ may be combined to form a 5- to 7-membered ring, and the ring may include O, N, S, P, and Si atoms. ) Having a molecular weight of 100 or more.
A method comprising less than 0 amide compound. 2. The method according to claim 1, wherein the amide compound is represented by the following chemical formula (2): (Wherein, R ₁ and R ₂ are as defined above, and R is 6 to 24)
A linear or branched alkyl or alkenyl group containing at least one carbon atom, wherein X is absent or contains one or more compounds selected from the group consisting of amides, esters, amines and ammonium Group. 2. The method according to claim 1, wherein the method is represented by: 3. The method of claim 2, wherein said linking group X comprises a second polar end group. 4. The amide compound according to chemical formula (3):(Where R, R₁, R_TwoIs as defined above, and l is 1 or
Or 2; m is 0 or 1; n is 1 or 2
And l + m + n = 3, and M is hydrogen, a metal atom,
Ammonia, primary organic amine, secondary organic amine or
Is a tertiary organic amine, and when 1 is 2, R is different
When n is 2, one of R ₁, R_TwoAnd already
One R₁, R_TwoMay be different. )
The method of claim 1 wherein the method is performed. 5. The amide compound according to chemical formula (4): (Wherein, l, m, n, R, R ₁ , and R _{2 are as} defined above, Y is a bonding group selected from alkylene, and when n is 2, Y may be a different group. The method according to claim 1, characterized by: 6. The amide compound according to chemical formula (5): (Wherein, M, R, R ₁ , R ₂ and Y are as defined above,
Z is a linking group selected from alkylene. 2. The method according to claim 1, wherein the method is represented by: