JP2001164274A - Agent for controlling formation of gas hydrate and method for controlling formation of gas hydrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agent for controlling the formation of a gas hydrate by the action to inhibit the formation of gas hydrate and the action to stabilize the gas hydrate from the viewpoint of equilibrium and reaction rate and provide a method for controlling the formation of a gas hydrate. SOLUTION: The agent for controlling the formation of a gas hydrate contains a polymer compound produced by the (co)polymerization of a vinyl monomer of formula (1) (R1, R2 and R3 are each independently H or a 1-2C alkyl group).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas hydrate production control agent such as methane hydrate and a method for controlling gas hydrate production.

[0002]

2. Description of the Related Art Water molecules surround dissolved gas molecules by placing an aqueous medium in which various gas molecules such as hydrocarbons such as methane and ethane and carbon dioxide gas are dissolved at a specific temperature and pressure. It is known that ice crystals, ie, gas hydrates, form. This gas hydrate is often produced during the extraction and transport of crude oil and natural gas,
This causes a blockage of the pipeline, etc., which is a major obstacle to safe and continuous operation.

On the other hand, it is known that gas hydrate exists naturally under high pressure and low temperature conditions. For example, under permafrost in cold regions such as Siberia and Alaska, or
Research has confirmed that a vast amount of methane gas hydrate (hereinafter referred to as methane hydrate) has been extensively deposited on the seabed deeper than several hundred meters. In recent years, methane hydrate has attracted attention as an energy source that emits less carbon dioxide, nitrogen and sulfur oxides, which are environmental pollution sources, and a method for safely extracting natural methane hydrate in a stable state has been desired. I have.

[0004] In order to solve the above-mentioned problems in transporting and storing the extracted gas hydrate and in extracting the gas hydrate from the sea floor or the ground floor, the following seemingly contradictory performances are required. It is required for the gas hydrate production control agent to be compatible. (1) The generation of gas hydrate is inhibited or the generation rate is reduced. (2) Promote the formation of gas hydrate (equilibrium stabilization) or reduce the decomposition rate of the generated gas hydrate (kinetic stabilization).

[0005] International Patent Publication No. WO 98/53007 discloses various additives having the function of inhibiting the formation and growth of gas hydrate and / or the aggregation of unstable core structures at the initial stage of gas hydrate formation, and the formation of various additives. Gas hydrate stabilizers are described. Specifically, it describes a homopolymer of acryloylpyrrolidine, a homopolymer of acryloylpiperidine, a copolymer of isopropylacrylamide and 2-acrylamido-2-methylpropanesulfonate, and the like. However, the effects of these polymers are not always satisfactory.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to form a gas hydrate having both a function of inhibiting gas hydrate formation and a function of stabilizing the gas hydrate equilibrium and kinetic. It is to provide a control agent and a method for controlling generation of gas hydrate.

[0007]

SUMMARY OF THE INVENTION The present invention is a gas hydrate production control agent comprising a polymer compound obtained by (co) polymerizing a vinyl monomer represented by the formula (1). .

[0008]

Embedded image (Wherein, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms.) In the present invention, the gas hydrate generation controlling agent is This is a method for controlling the generation of gas hydrate, which is added to a system capable of generating a rate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer compound contained in the gas hydrate formation controlling agent of the present invention is obtained by (co) polymerizing the vinyl monomer represented by the above formula (1). . In the formula (1), R ¹ , R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms. Specific examples of the vinyl monomer represented by the formula (1) include glycosyloxyethyl acrylate, glycosyloxyethyl methacrylate, glycosyloxyethyl-α-ethyl acrylate, glycosyloxyethyl-β-methyl acrylate, and glycosyloxyethyl. -Β, β-dimethyl acrylate, glycosyloxyethyl-β-ethyl acrylate, glycosyloxyethyl-β, β-diethyl acrylate, etc., among which glycosyloxyethyl acrylate and glycosyloxyethyl methacrylate are preferred.

The polymer compound obtained by (co) polymerizing the vinyl monomer represented by the formula (1) contained in the gas hydrate production controlling agent of the present invention is obtained by homopolymerizing this monomer. Or a copolymer copolymerized with another monomer. However, it is preferable that the vinyl monomer represented by the formula (1) is copolymerized with another monomer at a ratio of 0.01 to 80 mol%, and particularly, at a ratio of 0.05 to 50 mol%. Polymerized ones are preferred.

The monomer copolymerizable with the vinyl monomer represented by the formula (1) may be any monomer having a reactive group copolymerizable with the formula (1) such as a vinyl group. For example, N-
(Meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N
-Ethyl-N-methyl (meth) acrylamide, N, N
-Diethyl (meth) acrylamide, Nn-propyl- (meth) acrylamide, N-isopropyl- (meth) acrylamide, N, N-di-n-propyl- (meth) acrylamide, N-vinylpyrrolidone, N-vinyl Caprolactam, N-isopropenylpyrrolidone, N
-Isopropenylcaprolactam, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl-N-methylformamide, N-vinyl-N-propionamide, (meth) acryloylpyrrolidine, (meth) ) Acryloylpiperidine, (meth) acryloylhexamethyleneimine, (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate,
Vinyl acetate, vinyl propionate, methyl vinyl ether, ethyl vinyl ether, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2
-Isopropyl-2-oxazoline, (meth) acryloylpiperidine, methyl (meth) acrylate, (meth) acrylic acid, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (Meth) acrylate, tetrahydrofurfuryl (meth) acrylate, hydroxypropyl (meth) acrylate and the like. Among these monomers, water-soluble ones are preferable. Examples of such monomers include N- (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N- Ethyl-N-methyl (meth) acrylamide, N, N-diethyl (meth) acrylamide,
Nn-propyl- (meth) acrylamide, N-isopropyl- (meth) acrylamide, N, N-di-n-
Propyl- (meth) acrylamide, N-vinylpyrrolidone, N-vinylcaprolactam, N-isopropenylpyrrolidone, N-isopropenylcaprolactam, N-
Vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl-N-methylformamide, N-vinyl-N-propionamide,
(Meth) acryloylpyrrolidine, (meth) acryloylpiperidine, (meth) acryloylhexamethyleneimine, (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, and the like.

The method of copolymerization is not particularly limited, and a known method can be used. As such a copolymerization method, for example, a solution obtained by dissolving a monomer represented by the formula (1), a monomer to be copolymerized, and a polymerization initiator in an arbitrary solvent is dissolved in a heated solvent. And the like. As the type of the polymerization initiator, an azo type, a peroxide type, a redox type or the like is used.

The gas hydrate formation controlling agent of the present invention is a polymer compound itself obtained by (co) polymerization in this way, or a composition containing this polymer compound as an active ingredient. The molecular weight of this polymer compound is preferably in the range of 1,000 to 500,000, and more preferably in the range of 3,000 to 100,000. The larger the molecular weight is, the more the gas hydrate stabilizing effect and the generation suppressing effect are improved.

According to the method for controlling the production of gas hydrate of the present invention, the above-mentioned agent for controlling the production of gas hydrate of the present invention is added to a system capable of producing gas hydrate. Here, “a system capable of producing gas hydrate” refers to, for example, J. Long, A. Lederhos, A. Sum, R. Chris
tiansen, ED Sloan; Prep. 73rd Ann. GPA Conv., 1
994, pages 1-9, refers to a system in which a substance that forms gas hydrate is dissolved in an aqueous solvent. In such a system, gas hydrate precipitates as a crystal under specific pressure and temperature conditions.

The substance forming the gas hydrate includes gases such as carbon dioxide, nitrogen, oxygen, hydrogen sulfide, argon, xenon, ethane and propane, and liquids such as tetrahydrofuran.

As a system capable of producing gas hydrate, for example, in a natural gas well or oil well, an aqueous phase in which a gas such as ethane or propane is dissolved in an aqueous solvent such as water or seawater is used as a liquefied gas or a crude oil. And a system in which a gaseous phase such as natural gas exists in the aqueous phase.

The method for adding the gas hydrate production controlling agent of the present invention to a system capable of producing gas hydrate is not particularly limited, but it is preferable to add the gas hydrate production controlling agent after dissolving it in water and / or a water-miscible solvent. . The water-miscible solvent refers to a solvent that is mixed with water at an arbitrary ratio, for example,
Examples include methanol, ethanol, and acetone.

In the present invention, the gas hydrate formation controlling agent to be added includes one type of formation controlling agent other than the polymer compound obtained by (co) polymerizing the vinyl monomer represented by the formula (1). Alternatively, two or more kinds may be included. In that case, the proportion of the polymer compound obtained by (co) polymerizing the vinyl monomer represented by the formula (1) in the entire gas hydrate formation controlling agent is preferably 10% by mass or more, particularly 50% by mass.
The above is preferred.

The amount of the gas hydrate formation controlling agent to be added is preferably 0.01 to 30 parts by mass, more preferably 0.01 to 30 parts by mass, per 100 parts by mass of free water contained in the system capable of producing gas hydrate. 10 parts by mass is more preferred. The larger the amount of the gas hydrate production control agent added, the more the gas hydrate stabilizing effect increases, and the smaller the amount, the lower the viscosity of the system and the higher the flowability. However, if the amount of addition is extremely large, the effect of stabilizing the gas hydrate may be reduced.

When using the gas hydrate generation controlling agent of the present invention, various additives such as a rust inhibitor, a lubricant, a dispersant, a scale adhesion inhibitor, a corrosion inhibitor and the like are used in combination. Is also good.

[0021]

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

<Evaluation Apparatus> The gas hydrate generation controlling agent has the gas hydrate generation inhibiting performance, gas hydrate equilibrium stabilization performance, and gas hydrate kinetic stabilization performance as shown in the apparatus shown in FIG. Was evaluated using

In this apparatus, the reaction high-pressure cell 1 has an internal capacity of 100 ml and has a normal withstand pressure design up to 20 MPa. This cell is provided with a gas introduction line 1, a liquid introduction line 2, a purge line 3, a cell thermometer 5, a cell pressure gauge 6, and a reaction cell stirrer 7. The entire cell is housed in a thermostat 8, and the temperature in the cell can be adjusted by the temperature of the thermostat 8. In the reaction high pressure cell 1,
Three internal observation windows (not shown) having a diameter of 3 cm are provided at three locations so that the inside of the cell can be observed.

<Evaluation Method of Production Inhibition Performance> The gas hydrate production inhibition performance was evaluated as follows. That is,
A 0.5 mass% aqueous solution of a gas hydrate production control agent to be evaluated was introduced from a liquid introduction line 2, and methane gas was introduced from a gas introduction line 1 to reduce the pressure inside the cell to 10%.
The pressure in the cell was set to 20 ° C., which is a temperature clearly higher than the methane hydrate formation equilibrium temperature at that pressure. -4 ° C while stirring the inside of the cell
When the temperature inside the cell is gradually decreased at / hr, a state in which methane hydrate is generated inside the cell at a certain temperature is observed. The generation of methane hydrate lowers the pressure in the cell, and at the same time, the generation of gas hydrate is an exothermic reaction, so that the temperature in the cell slightly increases. It was evaluated that the lower the temperature in the cell at which the pressure starts to drop significantly, that is, the lower the methane hydrate formation temperature, the greater the gas hydrate formation inhibition performance.

<Evaluation Method of Equilibrium Stabilization Performance> Equilibrium stabilization performance was evaluated as follows. That is, after measuring the methane hydrate generation temperature in the above-described performance evaluation, lower the temperature of the constant temperature bath by 2 ° C. from the methane hydrate generation start temperature, and leave until the cell pressure and the cell temperature become constant. I do. Thereafter, the temperature in the cell was set at 4 ° C./hr.
As the pressure rises, the methane hydrate in the cell gradually begins to decompose and eventually completely separates into water and methane gas.
It was evaluated that the higher the temperature in the cell, that is, the temperature at which methane hydrate was decomposed, the higher the equilibrium stabilization performance against gas hydrate.

<Evaluation Method of Kinetic Stabilization Performance> The kinetic stabilization performance of kinetically decreasing the decomposition rate of gas hydrate and delaying the decomposition of gas hydrate was evaluated as follows. That is, after generating methane hydrate in the same procedure as measuring the methane hydrate generation temperature in the evaluation of the generation inhibition performance described above, the temperature in the constant temperature bath was set to 2 ° C., and the pressure in the cell and the temperature in the cell were lowered. Leave until constant. Thereafter, the methane gas in the cell is discharged to set the pressure in the cell to 2 MPa. The cell was sealed under these conditions, and the time until the pressure in the cell became constant was measured. It was evaluated that the longer this time (hereinafter referred to as “kinetic decomposition delay time”), the greater the kinetic stabilization performance in the decomposition of methane hydrate.

Example 1 In a 300 ml separable flask, 74 g of a 50% by mass aqueous solution of glycosyloxyethyl methacrylate monomer (including 37 g of glycosyloxyethyl methacrylate monomer manufactured by Nippon Seika) and 16 g of N-isopropyl methacrylamide And 150 g of methyl ethyl ketone, and then dissolved oxygen was removed by bubbling with nitrogen. Thereafter, the temperature in the flask was raised to 80 ° C., and a solution prepared by dissolving 1.0 g of 2,2′-azobisisobutyronitrile, which is an azo initiator, in 8 g of methyl ethyl ketone was added as a polymerization initiator. The polymerization was started. Polymerization is performed while stirring under nitrogen flow,
The reaction was continued at 80 ° C. for 8 hours. After allowing to cool, this polymerization solution was poured into 2 L of n-hexane while stirring, and the polymer obtained as a precipitate was vacuum-dried at 70 ° C. After dissolving this polymer in 200 g of acetone, it was again added dropwise to 2 L of n-hexane, and the polymer obtained as a precipitate was vacuum-dried at 70 ° C. overnight to obtain 50 g of a white powdery polymer.

The composition of the obtained polymer was measured by ¹ H-NMR. As a result, the composition ratio of glycosyloxyethyl methacrylate was 50 mol%. As a result of molecular weight measurement using GPC using dimethylformamide as a mobile phase, the number average molecular weight was found to be 18.0 or less in terms of standard polystyrene.
00, and the weight average molecular weight was 38,000.

When the thus obtained glycosyloxyethyl methacrylate / N-isopropylmethacrylamide copolymer (gas hydrate formation controlling agent) was evaluated, the gas hydrate formation temperature was 4 ° C., and the gas hydrate decomposition was performed. The termination temperature was 16 ° C. and the kinetic decomposition delay time was 315 minutes.

[0030]

The gas hydrate formation controlling agent of the present invention can be used under the conditions where gas hydrate is formed.
It has an inhibitory effect of suppressing its formation, and conversely has the effect of stabilizing the gas hydrate equilibrium and kinetic under conditions where the gas hydrate is gradually decomposed. By using the gas hydrate generation controlling agent of the present invention having both these effects, the gas hydrate generation can be effectively controlled.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for evaluating the performance of a gas hydrate production control agent.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas introduction line 2 Liquid introduction line 3 Purge line 4 High-pressure cell for reaction 5 Thermometer in reaction cell 6 Pressure gauge in reaction cell 7 Stirrer in reaction cell 8 Constant temperature bath

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4J100 AE03Q AE04Q AG02Q AG04Q AJ02Q AL03Q AL08P AL08Q AL09Q AL16P AM15Q AM17Q AM19Q AN04Q AQ06Q AQ08Q AQ15Q BA02P BA03P BA31Q BC53P BC53Q BC65Q BC79Q CA04 JA24

Claims (5)

[Claims] 1. A gas hydrate generation controlling agent comprising a polymer compound obtained by (co) polymerizing a vinyl monomer represented by the formula (1). Embedded image (Wherein, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms) 2. The gas according to claim 1, wherein the polymer compound is obtained by copolymerizing the vinyl monomer represented by the formula (1) at a ratio of 0.01 to 80 mol%. Hydrate formation control agent. 3. A method for controlling production of gas hydrate, comprising adding the production control agent for gas hydrate according to claim 1 or 2 to a system capable of producing gas hydrate. 4. The gas according to claim 3, wherein the hydrate production controlling agent according to claim 1 or 2 dissolved in water and / or a solvent miscible with water is added to a system capable of producing gas hydrate. Hydrate generation control method. 5. The amount of the gas hydrate formation controlling agent according to claim 1 or 2 is 0.01 to 100 parts by mass of free water contained in a system capable of forming a gas hydrate.
5 to 30 parts by mass.
A method for controlling generation of gas hydrate according to the above.