JP2015193529A - cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement composition exhibiting sufficient cure delay property, even under high temperature.SOLUTION: The cement composition includes a polymer having a carboxylic acid function (basic function) whose thermal decomposition temperature is equal to or more than 250°C, and cement.

Description

The present invention relates to a cement composition containing a polymer having a carboxylic acid (salt) group.

In well drilling such as oil and gas fields, a steel pipe called a casing pipe is inserted into the well immediately after drilling to protect the well. The gap between the outside of the casing pipe and the hole wall is necessary to prevent the collapse of the pit wall, to prevent the formation fluid from moving between multiple formations, or to ensure that the casing pipe is securely fixed. The method of filling cement with is widely adopted.
Here, because wells such as oil and gas fields can reach several thousand meters deep, they are premised on use under high temperature and high pressure, unlike civil engineering and construction. Since the cement slurry needs to maintain sufficient fluidity while being fed into the well by a pump, a curing retarder or the like is blended.

For example, Patent Document 1 discloses an oil well cement composition containing a lignin retarder. Patent Document 2 discloses an additive for soil cement containing a specific phosphate ester polymer. Further, Patent Document 3 discloses an oil well or gas well cement composition containing alumina cement.

JP 2008-214537 A JP 2007-169547 A US Pat. No. 5,488,991

As described above, various oil well cement compositions containing cure retarders have been proposed, but for example, lignin compounds contained in lignin retarders do not have sufficient heat resistance and sufficiently exhibit cure retardance at high temperatures. There was a problem that I could not. Other curing retarders were also not able to sufficiently exhibit curing retardance at high temperatures.
Therefore, an object of this invention is to provide the cement composition which expresses sufficient hardening retardance also under high temperature.

As a result of intensive studies, the present inventors have found that the cement composition contains a predetermined polymer, so that sufficient curing retardation can be obtained even at high temperatures, and the present invention has been completed based on these findings. did.

That is, the present invention is a cement composition comprising a polymer having a carboxylic acid (salt) group having a thermal decomposition temperature of 250 ° C. or more and a cement.
The present invention also provides a polymer comprising a structural unit derived from (meth) acrylic acid (salt), a structural unit derived from a monomer having a sulfonic acid (salt) group, and a cement composition containing cement. It may be a thing.

The cement composition of the present invention has good cure retardance even at high temperatures. Therefore, it can be favorably used for cementing wells such as oil fields and gas fields.

It is a chart of TG-DTA measurement of a polymer (1). It is the chart which evaluated the hardening behavior of the cement composition which added polymer (1), (5), comparative polymer (1), and ligninsulfonic acid with the isothermal calorimeter, respectively.

Hereinafter, the present invention will be described in detail.
A combination of two or more preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

In the following, first, a polymer having a carboxylic acid (salt) group according to the present invention will be described. Next, the curing retarder of the present invention using the polymer having a carboxylic acid (salt) group according to the present invention and the cement composition of the present invention will be described.

(Polymer having carboxylic acid (salt) group)
The cement composition of the present invention includes a polymer having a carboxylic acid (salt) group.
In the present invention, the polymer having a carboxylic acid (salt) group refers to a polymer having one or more carboxylic acid (salt) groups in the molecule, but is derived from a monomer having a carboxylic acid (salt) group. It is preferable to include a structural unit.

The “carboxylic acid (salt) group” represents at least one selected from a carboxylic acid group and a carboxylic acid group, and the carboxylic acid group refers to a metal salt, ammonium salt, organic amine salt, or the like of a carboxylic acid. . Examples of the metal salt include salts of alkali metals such as sodium and potassium; salts of alkaline earth metals such as calcium and magnesium; salts of transition metals such as iron and copper; Examples of the organic amine salt include primary to quaternary amine salts, such as methylamine, trimethylamine and other alkylamine salts; monoethanolamine, diethanolamine, dipropanolamine and other alkanolamine salts; morpholine and piperidine. And the like, and the like.

The above-mentioned “structural unit derived from a monomer containing a carboxylic acid (salt) group” represents a structural unit formed by polymerization of a monomer containing a carboxylic acid (salt) group. (Salt) A structural unit having a structure in which one or two or more carbon-carbon double bonds contained in a monomer containing a group are changed to carbon-carbon single bonds. For example, when the monomer containing a carboxylic acid (salt) group is acrylic acid (CH ₂ ═CHCOOH), the structural unit derived from the monomer containing a carboxylic acid (salt) group is —CH ₂ —CH ( COOH)-.
The “structural unit derived from a monomer containing a carboxylic acid (salt) group” is a carboxylic acid (salt) as long as it has the same structure as the structural unit derived from a monomer containing a carboxylic acid (salt) group. ) A structural unit obtained by a method other than polymerizing a monomer containing a group is also included in the “structural unit derived from a monomer containing a carboxylic acid (salt) group”.

The “monomer containing a carboxylic acid (salt) group” is a compound containing in the molecule at least one carboxylic acid (salt) group and at least one carbon-carbon double bond. Specific examples of the monomer containing a carboxylic acid (salt) group include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, α-hydroxyacrylic acid, α-hydroxymethylacrylic acid and derivatives thereof. Examples thereof include acids and salts thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, itaconic acid, and methylene glutaric acid, and salts thereof (which may be mono- or di-salts); . The monomer containing the carboxylic acid (salt) group may be used alone or in combination of two or more.
Among these, since the retarding property of the cement composition is improved, the monomer containing a carboxylic acid (salt) group contains one or more selected from acrylic acid, methacrylic acid and salts thereof. It is preferable. Specifically, a structural unit derived from acrylic acid, acrylic, with respect to 100 mol% of a structural unit derived from a monomer containing a carboxylic acid (salt) group contained in a polymer having a carboxylic acid (salt) group. The total of structural units derived from acid salts, structural units derived from methacrylic acid, and structural units derived from methacrylic acid salts is preferably 80 to 100 mol%, more preferably 90 to 100 mol%. More preferably, it is 95-100 mol%.

The polymer having a carboxylic acid (salt) group is preferably a copolymer. For example, a polymer having a carboxylic acid (salt) group preferably has a sulfonic acid (salt) group, since the cement composition of the present invention tends to have a good cure retardance at high temperatures. More preferably, it contains a structural unit derived from a monomer having a sulfonic acid (salt) group. Thus, the present invention provides a cement composition comprising a polymer having a structural unit derived from (meth) acrylic acid (salt) and a structural unit derived from a monomer having a sulfonic acid (salt) group. It may be. The sulfonic acid (salt) group represents a sulfonic acid group and / or a sulfonic acid group. The salt in the sulfonate group is the same as the salt in the carboxylic acid group. The reason why the cement composition of the present invention has good cure retardance at high temperatures is attributed to the fact that the sulfonic acid (salt) group inhibits the polymer adsorbed on the cement from being deactivated. It is done.

The above-mentioned “structural unit derived from a monomer containing a sulfonic acid (salt) group” means a structural unit formed by polymerization of a monomer containing a sulfonic acid (salt) group. (Salt) A structural unit having a structure in which one or two or more carbon-carbon double bonds contained in a monomer containing a group are changed to carbon-carbon single bonds. For example, when the monomer containing a sulfonic acid (salt) group is sodium 3-allyloxy-2-hydroxypropanesulfonate (CH ₂ ═CHCH ₂ OCH ₂ CH (OH) CH ₂ SO ₃ Na), sulfonic acid ( structural unit derived from a monomer comprising a salt) _{groups, -CH 2 -CH (CH 2 OCH} 2 CH (OH) CH 2 SO 3 Na) -, it can be represented by.
The “structural unit derived from a monomer containing a sulfonic acid (salt) group” is a sulfonic acid (salt) as long as it has the same structure as the structural unit derived from a monomer containing a sulfonic acid (salt) group. ) A structural unit obtained by a method other than polymerizing a monomer containing a group is also included in the “structural unit derived from a monomer containing a sulfonic acid (salt) group”.

The “monomer containing a sulfonic acid (salt) group” is a compound containing in the molecule at least one sulfonic acid (salt) group and at least one carbon-carbon double bond. Specific examples of the monomer containing a sulfonic acid (salt) group include 2-acrylamido-2-methylpropanesulfonic acid, (meth) allylsulfonic acid, isoprenesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, 2 -Sulfoethyl (meth) acrylic acid and salts thereof, the following formula (1);

(In the formula, ^{R 1,} .R ² represents a hydrogen atom or a methyl group, a direct _bond, .X representing the structure of any of _{CH 2, CH 2 CH 2,} Y is a hydroxyl group or SO ₃ M group In the SO ₃ M group, M represents a hydrogen atom, Li, Na, or K, provided that at least one of X and Y represents a SO ₃ M group. Is exemplified. The monomer containing the sulfonic acid (salt) group may be used alone or in combination of two or more.

Incidentally, ^{R 2} in the formula (1) is preferably a CH _2. Moreover, it is preferable that either X or Y in the formula (1) is a SO ₃ M group, and the other is a hydroxyl group. More preferably, X is a hydroxyl group and Y is a SO ₃ M group. Specific examples of the compound represented by the above formula (1) include 3- (meth) allyloxy-2-hydroxypropanesulfonic acid (salt) and 3- (meth) allyloxy-1-hydroxypropanesulfonic acid (salt). More preferred is 3- (meth) allyloxy-2-hydroxypropanesulfonic acid (salt).

Among these, the monomer containing a sulfonic acid (salt) group preferably has at least one of a hydroxyl group, an ether group, and an amide group because the curing retardation of the cement composition is improved. It is more preferable to contain 1 type, or 2 or more types chosen from 3-allyloxy-2-hydroxy-1-propanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and salts thereof. Specifically, 3-allyloxy-2-hydroxy- with respect to 100 mol% of the structural unit derived from the monomer containing a sulfonic acid (salt) group contained in the polymer having the carboxylic acid (salt) group. Structural unit derived from 1-propanesulfonic acid, structural unit derived from salt of 3-allyloxy-2-hydroxypropanesulfonic acid, structural unit derived from 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamide-2 -The total of the structural units derived from the salt of methylpropanesulfonic acid is preferably 80 to 100 mol%, more preferably 90 to 100 mol%, and further preferably 95 to 100 mol%. .

Since the polymer having a carboxylic acid (salt) group tends to further improve the curing retardation of the cement composition and the thermal decomposition resistance of the polymer, hypophosphorous acid (salt) groups and It preferably contains a phosphorous acid (salt) group. The hypophosphorous acid (salt) group can be represented by, for example, -PH (= O) (ONa) or -P (= O) (ONa)-, for a sodium hypophosphite group. If the phosphoric acid (salt) group is, for example, a sodium phosphite group, it can be represented by -P (= O) (ONa) ₂ . The hypophosphorous acid (salt) group is obtained by using, for example, hypophosphorous acid (salt) as a chain transfer agent at the time of polymerization. Salt) can be introduced into the polymer molecule. Hypophosphorous acid (salt) group and phosphorous acid (salt) group can be quantified by ³¹ P-NMR or the like.

The polymer having a carboxylic acid (salt) group is a monomer other than a monomer having a carboxylic acid (salt) group or a monomer having a sulfonic acid (salt) group (hereinafter referred to as “other monomers”). And a structural unit derived from “)”. The above-mentioned “structural unit derived from other monomer” represents a structural unit formed by polymerization of another monomer, and usually one or more carbons contained in the other monomer. -A structural unit having a structure in which a carbon double bond is changed to a carbon-carbon single bond.

Specific examples of the other monomers include unsaturated alcohols such as 3- (meth) allyloxy-1,2-dihydroxypropane, (meth) allyl alcohol, isoprenol, and 2-hydroxyethyl (meth) acrylate. Monomers; polyalkylene glycol monomers having a structure in which an alkylene oxide is added to the unsaturated alcohol monomers; vinyl pyridine, vinyl imidazole, dimethylaminoethyl (meth) acrylate, diallyldimethylamine, and these Amino group-containing monomers such as quaternized products and salts of N-vinyl monomers such as N-vinylpyrrolidone, N-vinylformamide, N-vinyloxazolidone; methyl (meth) acrylate, (meth) acrylic acid Butyl, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate (Meth) acrylic esters such as; acrylamide monomers such as (meth) acrylamide and N, N-dimethylacrylamide; vinylaryl monomers such as styrene, indene and vinylaniline; alkenes such as isobutylene and octene; And vinyl carboxylates such as vinyl acetate and vinyl propionate. These other monomers may be used alone or in combination of two or more.

The polymer having a carboxylic acid (salt) group includes a structural unit derived from a monomer having a carboxylic acid (salt) group, a structural unit derived from a monomer having a sulfonic acid (salt) group, and other A structure derived from a monomer having a carboxylic acid (salt) group with respect to a total of 100 mol% of structural units derived from monomers (also referred to as “structural units derived from monomers”) The unit is preferably 50 mol% or more, more preferably 55 mol% or more, still more preferably 60 mol% or more, still more preferably 65 mol% or more, and 70 mol% or more. It is particularly preferred that The structural unit derived from the monomer having a carboxylic acid (salt) group is preferably 95 mol% or less, and more preferably 90 mol% or less.
The polymer having a carboxylic acid (salt) group has 5 mol% of structural units derived from a monomer having a sulfonic acid (salt) group with respect to a total of 100 mol% of structural units derived from the monomer. Preferably, it is preferably 10 mol% or more. The structural unit derived from the monomer having a sulfonic acid (salt) group is preferably 50 mol% or less, more preferably 45 mol% or less, and further preferably 40 mol% or less. Preferably, it is still more preferably 35 mol% or less, and particularly preferably 30 mol% or less.
The polymer having a carboxylic acid (salt) group may contain 0 to 20 mol% of structural units derived from other monomers with respect to a total of 100 mol% of structural units derived from monomers. Preferably, it is 0 to 15 mol%, more preferably 0 to 10 mol%.
The polymer having the carboxylic acid (salt) group has 0 to 10% by mass of structural units derived from other monomers with respect to 100% by mass of the total structural units derived from monomers. Is particularly preferred.
When the structural unit derived from the monomer is in the above range, the heat resistance of the copolymer is improved, and the retarding property of the cement composition of the present invention tends to be improved.
The total mass of structural units derived from the monomers contained in 100% by mass of the polymer having a carboxylic acid (salt) group is 90 to 100% by mass (provided that the carboxylate group, the sulfonate group, The other acid group salts are preferably calculated as corresponding carboxylic acid groups, sulfonic acid groups, and other acid groups, respectively.

When the polymer having a carboxylic acid (salt) group is a copolymer, each constituent unit of the copolymer is regularly present, whether in a block form or a random form. It doesn't matter.

The polymer having a carboxylic acid (salt) group preferably has a weight average molecular weight of 500 or more, more preferably 1000 or more, and still more preferably 5000 or more. The weight average molecular weight is preferably 1000000 or less, more preferably 500000 or less, still more preferably 400000 or less, still more preferably 300000 or less, and particularly preferably 200000 or less. preferable. By being in the above range, the retarding property of the cement composition of the present invention tends to be improved. In addition, the said weight average molecular weight can be measured with the measuring method mentioned later.

The polymer having a carboxylic acid (salt) group preferably has a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.5 or more and 30 or less, and preferably 1.6 or more and 20 or less. More preferred. The weight average molecular weight / number average molecular weight (Mw / Mn) is more preferably 9 or less from the viewpoint of further improving the retarding property. In addition, said Mw / Mn can be measured with the measuring method mentioned later.

The polymer having a carboxylic acid (salt) group is one of the preferred forms that have a thermal decomposition temperature (thermal decomposition start temperature) of 250 ° C. or higher. More preferably, it is 250-600 degreeC, More preferably, it is 250-500 degreeC. By being the said range, it can be used conveniently for the cementing of wells, such as a gas field, and the civil engineering of a geothermal ground. In addition, the said thermal decomposition temperature can be measured by the method mentioned later.

The polymer having a carboxylic acid (salt) group includes a monomer having a carboxylic acid (salt) group and, if necessary, a monomer having a sulfonic acid (salt) group and / or other monomers. It is preferable to produce by including a step of polymerizing. In the above step, the total of the monomer having a carboxylic acid (salt) group, the monomer having a sulfonic acid (salt) group, and another monomer (these are also simply referred to as “monomer”) The amount of the monomer having a carboxylic acid (salt) group is preferably 50 mol% or more, more preferably 55 mol% or more, and 60 mol% or more with respect to 100 mol% of More preferably, it is more preferable to set it as 65 mol% or more, and it is especially preferable to set it as 70 mol% or more. The amount of the monomer having a carboxylic acid (salt) group is preferably 95 mol% or less, more preferably 90 mol% or less. Moreover, it is preferable that the total usage amount of acrylic acid, methacrylic acid and these salts is 80 to 100 mol% with respect to the usage amount of 100 mol% of the monomer containing a carboxylic acid (salt) group, More preferably, it is 90-100 mol%, and it is further more preferable that it is 95-100 mol%.

The amount of the monomer having a sulfonic acid (salt) group in the above step is preferably 5 mol% or more, preferably 10 mol% or more, based on 100 mol% of the total amount of monomers used. It is more preferable. The amount of the monomer having a sulfonic acid (salt) group is preferably 50 mol% or less, more preferably 45 mol% or less, and further preferably 40 mol% or less. Is more preferably 35 mol% or less, and particularly preferably 30 mol% or less.
Further, the total amount of 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid and salts thereof with respect to 100 mol% of the monomer containing a sulfonic acid (salt) group Is preferably 80 to 100 mol%, more preferably 90 to 100 mol%, and still more preferably 95 to 100 mol%.

The amount of other monomers used in the above process is preferably 0 to 20 mol%, more preferably 0 to 15 mol%, based on 100 mol% of the total amount of monomers used. 0 to 10 mol% is more preferable.
The amount of other monomers used in the above process is particularly preferably 0 to 10% by mass with respect to 100% by mass of the total amount of monomers used.

The polymerization in the polymerization step is performed by various conventionally known methods such as solution polymerization method, bulk polymerization, suspension polymerization method, reverse phase suspension polymerization method, cast polymerization method, thin film polymerization method, spray polymerization method, etc. Can be adopted. Although not particularly limited, solution polymerization is preferred. The polymerization step can be carried out either batchwise or continuously.

In the polymerization step, a polymerization initiator is preferably used when the polymerization is performed. Examples of the polymerization initiator include hydrogen peroxide; persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; dimethyl 2,2′-azobis (2-methylpropionate), 2,2′- Azobis (isobutyronitrile), 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate , 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, etc. An organic peroxide such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, cumene hydroperoxide and the like is preferable. Of these polymerization initiators, hydrogen peroxide and persulfate are preferable, and persulfate is most preferable. These polymerization initiators may be used alone or in the form of a mixture of two or more.
The amount of the polymerization initiator used is preferably 0.1 g or more and 20 g or less, more preferably 0.2 g or more and 18 g or less with respect to 1 mol of the monomer used.

In the polymerization step, a chain transfer agent may be used as necessary. Specific examples of chain transfer agents include thiol chain transfer agents such as mercaptoethanol, thioglycolic acid, mercaptopropionic acid, and n-dodecyl mercaptan; halogens such as carbon tetrachloride, methylene chloride, bromoform, and bromotrichloroethane. Secondary alcohols such as isopropanol and glycerin; hypophosphorous acid (salts) such as hypophosphorous acid and sodium hypophosphite (including hydrates thereof); phosphorous acid and sodium phosphite Phosphorous acid (salt) such as sodium sulfite (salt) such as potassium sulfite; Sodium bisulfite (sodium bisulfite), bisulfite (salt) such as potassium hydrogen sulfite; Dithionic acid such as sodium dithionite (Salt); pyrosulfurous acid (salt) such as potassium pyrosulfite; The chain transfer agent may be used alone or in the form of a mixture of two or more. As described above, it is preferable to use hypophosphorous acid (salt) (including these hydrates) and / or phosphorous acid (salt).
The amount of the chain transfer agent used is preferably 0 g or more and 20 g or less, and more preferably 0 g or more and 15 g or less, with respect to 1 mol of the monomer used.

In the polymerization step, heavy metal ions may be used for the purpose of promoting the reaction. In the present invention, the heavy metal ion means a metal ion having a specific gravity of 4 g / cm ³ or more. By using heavy metal ions, the amount of polymerization initiator used can be reduced. The heavy metal ions are not particularly limited as long as they are included in the form of ions. However, it is preferable to use a method using a solution in which a heavy metal compound is dissolved because the handleability is excellent. Examples of the heavy metal compound include molle salt (Fe (NH ₄ ) ₂ (SO ₄ ) ₂ · 6H ₂ O), ferrous sulfate / pentahydrate, ferrous chloride, ferric chloride, manganese chloride, and the like. Illustrated.
The amount of the heavy metal ion used is preferably 0 ppm or more and 100 ppm or less, and more preferably 0 ppm or more and 50 ppm or less with respect to the total amount of the polymerization reaction solution.

The polymerization step preferably uses a solvent. The solvent preferably contains water, more preferably contains 50% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, based on the total amount of the solvent. Solvents usable in the polymerization step include water; lower alcohols such as methanol, ethanol and isopropyl alcohol; lower ketones such as acetone, methyl ethyl ketone and diethyl ketone; ethers such as dimethyl ether and dioxane; amides such as dimethylformaldehyde. Kind. These solvents may be used alone or in the form of a mixture of two or more.
As a usage-amount of a solvent, 40-300 mass% is preferable with respect to 100 mass% of monomers. More preferably, it is 45 mass% or more, More preferably, it is 50 mass% or more. Moreover, More preferably, it is 270 mass% or less, More preferably, it is 250 mass% or less. If the amount of the solvent used is less than 40% by mass, the molecular weight of the resulting polymer may increase. If it exceeds 300% by mass, the concentration of the obtained polymer will be low, and the cost for storage and the like will be high. There is a risk.

The polymerization in the polymerization step is usually preferably performed at 0 ° C. or higher, and preferably 150 ° C. or lower. More preferably, it is 40 degreeC or more, More preferably, it is 60 degreeC or more, Most preferably, it is 80 degreeC or more. Moreover, More preferably, it is 120 degrees C or less, More preferably, it is 110 degrees C or less.
The polymerization temperature does not necessarily need to be kept almost constant in the polymerization reaction. For example, the polymerization is started from room temperature, the temperature is raised to a set temperature with an appropriate temperature increase time or rate, and then the set temperature is increased. You may make it hold | maintain and you may carry out temperature fluctuation (temperature rise or temperature fall) with time during a polymerization reaction according to dripping methods, such as a monomer component and an initiator.

The polymerization time in the polymerization step is not particularly limited, but is preferably 30 to 420 minutes, more preferably 45 to 390 minutes, still more preferably 60 to 360 minutes, and most preferably 90 to 300 minutes. . In the present invention, “polymerization time” represents the time during which a monomer is added unless otherwise specified.

When some or all of the acid groups of the polymer having a carboxylic acid (salt) group are neutralized, in the polymerization step, the monomer remains unneutralized or a predetermined neutralization rate Polymerization is performed at a lower neutralization rate, and may be neutralized to a predetermined degree of neutralization after polymerization, or may be performed while neutralizing the monomer. You may do it.

The pressure in the reaction system in the polymerization step may be any of normal pressure (atmospheric pressure), reduced pressure, and increased pressure, but in terms of molecular weight of the resulting polymer, the reaction may be performed under normal pressure or reaction. It is preferable to carry out under pressure while the system is sealed. Moreover, it is preferable to carry out under a normal pressure (atmospheric pressure) at the point of equipment, such as a pressurization apparatus, a pressure reduction apparatus, a pressure-resistant reaction container, and piping. The atmosphere in the reaction system may be an air atmosphere or an inert atmosphere. For example, the inside of the system may be replaced with an inert gas such as nitrogen before the start of polymerization.

The polymer having the carboxylic acid (salt) group is optional, but may be produced by including steps other than the polymerization step. Examples of the process other than the polymerization process include an aging process, a neutralization process, a deactivation process of a polymerization initiator and a chain transfer agent, a dilution process, a drying process, a concentration process, and a purification process.

When the polymer having a carboxylic acid (salt) group is solid, the neutralization step is preferably performed by dissolving in a solvent such as water and adding an alkali compound to the solution. Examples of the alkali compound include hydroxides such as sodium hydroxide, potassium hydroxide, and calcium hydroxide; carbonates such as sodium carbonate, potassium carbonate, and sodium bicarbonate; organic amines such as monoethanolamine and diethanolamine. .

(Curing retarder of the present invention)
The polymer having a carboxylic acid (salt) group can be used as a curing retarder for cement (composition). Since the polymer having a carboxylic acid (salt) group exhibits good thermal decomposition resistance, it can be preferably used as a curing retarder for an oil well or gas well cement composition.
That is, this invention is also a cement hardening retarder containing the polymer which has a carboxylic acid (salt) group whose thermal decomposition temperature is 250 degreeC or more, for example.
The polymer preferably includes a structural unit derived from (meth) acrylic acid (salt) and a structural unit derived from a monomer having a sulfonic acid (salt) group.
The present invention is also a cement curing retarder comprising a polymer comprising a structural unit derived from (meth) acrylic acid (salt) and a structural unit derived from a monomer having a sulfonic acid (salt) group. Also good.

The curing retarder of the present invention essentially contains the polymer having the carboxylic acid (salt) group, and may contain only the polymer having the carboxylic acid (salt) group.
The preferred form of the polymer having a carboxylic acid (salt) group is as described above.
The curing retarder of the present invention preferably contains, for example, 1% by mass to 100% by mass of the polymer having a carboxylic acid (salt) group.
The curing retarder of the present invention may contain a solvent. The content of the solvent is preferably 0% by mass or more and 99% by mass or less.

The curing retarder of the present invention may further contain hypophosphorous acid (salt) and / or phosphorous acid (salt) since the thermal decomposability and curing retardance at high temperatures are further improved. The content of hypophosphorous acid (salt) and / or phosphorous acid (salt) is 0.1% by mass or more and 10% by mass or less based on the polymer having the carboxylic acid (salt) group. preferable.
The curing retarder of the present invention may contain a compound having a known curing retardation other than the polymer having the carboxylic acid (salt) group.

(Cement composition of the present invention)
[cement]
The cement composition of the present invention contains cement together with the polymer having the carboxylic acid (salt) group. The polymer having a carboxylic acid (salt) group exhibits good curing retardancy with respect to various cements, and thus the cement is not limited. For example, Portland cement (ordinary, early strength, very early strength, medium strength) Heat, sulfate resistant and low alkali type of each, various mixed cement (blast furnace cement, silica cement, fly ash cement), white Portland cement, alumina cement, super fast cement (1 clinker fast cement, 2 clinker fast cement) , Magnesium phosphate cement), grout cement, oil well cement (oil well cement), low exothermic cement (low exothermic blast furnace cement, fly ash mixed low exothermic blast furnace cement, high cement containing belite), ultra high strength cement , Cement-based solidification material, eco-cement (city waste burning Ash, cement manufactured using one or more types of sewage sludge incineration ash as raw materials), and fine powders such as blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, silica fume, silica powder, limestone powder, etc. Body and gypsum may be added. In addition to gravel, crushed stone, granulated slag, recycled aggregate, etc., the aggregates are siliceous, clay, zircon, high alumina, silicon carbide, graphite, chrome, chromic, magnesia. Refractory aggregate such as can be used.
When the cement composition of the present invention is used particularly for oil wells or gas wells, it is usually preferable to use oil well cement. As the oil well cement, any of Class A cement to Class H cement of API (American Petroleum Institute) standard “APISPEC 10A Specification for Materials and Wells for Well” can be used. It is more preferable because the component adjustment is easy. Examples of the class G cement include oil well cement OWC-G manufactured by Ube Mitsubishi Cement Co., Ltd.

[Other ingredients]
The cement composition of the present invention may contain an optional component as desired in addition to the polymer having a carboxylic acid (salt) group and cement.
For example, water reducing agent having lignin sulfonic acid, melamine sulfonic acid, naphthalene sulfonic acid, polyalkylene glycol chain and acid group; polymer emulsion such as copolymer of various vinyl monomers such as alkyl (meth) acrylate; Retarding agents other than the above-mentioned polymer having a carboxylic acid (salt) group such as gluconic acid; soluble calcium salts such as calcium chloride, calcium nitrite, calcium nitrate, calcium bromide, calcium iodide, iron chloride, magnesium chloride, etc. Fasteners / accelerators such as chloride, sulfate, potassium hydroxide, sodium hydroxide, carbonate, thiosulfate, formate such as formic acid and calcium formate, alkanolamine, alumina cement, calcium aluminate silicate; Mineral oil-based antifoaming agents such as coconut oil and liquid paraffin; animal and vegetable oils, sesame oil, castor oil, these Fatty antifoaming agents such as alkylene oxide adducts; oleic acid, stearic acid, fatty acid antifoaming agents such as these alkylene oxide adducts; glycerin monoricinolate, alkenyl succinic acid derivatives, sorbitol monolaurate, sorbitol trioleate Fatty acid ester antifoaming agents such as natural wax; oxyethylene oxypropylene copolymers, oxyalkylene antifoaming agents such as compounds obtained by adding 1 mol or 2 mol or more of ethylene oxide and / or propylene oxide to higher alcohols and higher amines ; Alcohol defoamers such as octyl alcohol, hexadecyl alcohol, acetylene alcohol, glycols; Amide defoamers such as acrylate polyamines; Phosphate defoamers such as tributyl phosphate and sodium octyl phosphate ; Metal soap antifoaming agents such as aluminum stearate and calcium oleate; Silicone antifoaming agents such as dimethyl silicone oil, silicone paste, silicone emulsion, organically modified polysiloxane (polyorganosiloxane such as dimethylpolysiloxane) and fluorosilicone oil Foaming agent; resin soap, saturated or unsaturated fatty acid, sodium hydroxystearate, lauryl sulfate, ABS (alkyl benzene sulfonic acid), LAS (linear alkyl benzene sulfonic acid), alkane sulfonate, polyoxyethylene alkyl (phenyl) ether, polyoxy Ethylene alkyl (phenyl) ether sulfate or its salt, polyoxyethylene alkyl (phenyl) ether phosphate or its salt, protein material, alkenyl sulfoco AE agents such as succinic acid and α-olefin sulfonate; other surfactants; waterproofing agents such as fatty acids (salts), fatty acid esters, fats and oils, silicon, paraffin, asphalt, wax; nitrites, phosphates, zinc oxide, etc. Antirust agent for cracking; Crack reducing agent such as polyoxyalkyl ether; Expansion agent such as ettringite and coal; Others, cement wetting agent, thickener, separation reducing agent, flocculant, drying shrinkage reducing agent, strength enhancer Examples thereof include a self-leveling agent, a coloring agent, and an antifungal agent.

As described above, the cement composition of the present invention contains the polymer having the carboxylic acid (salt) group and cement as essential components.
The polymer having a carboxylic acid (salt) group in the cement composition of the present invention is 0.01 to 10% by mass with respect to 100% by mass of cement because it exhibits an excellent curing delay effect. Is preferable, and it is more preferable that it is 0.05-8 mass%.
The cement composition of the present invention preferably contains 90 to 99.99 mass%, more preferably 92 to 99.95 mass% of cement with respect to 100 mass% of the cement composition of the present invention.
The content of the other components in the cement composition of the present invention is preferably 0 to 9.99% by mass with respect to 100% by mass of the cement composition of the present invention.

The cement composition of the present invention expresses good curing delay, but the secondary hydration peak time described below is preferably 15 to 50 hours, more preferably 15 to 40 hours. Preferably, it is 15 to 30 hours. If it is the said range, sufficient retarding property can be expressed even under high temperature and high pressure.

As described above, the cement composition of the present invention can be used for oil well and gas well drilling applications, but can also be used for civil engineering / architecture, dental use, geothermal well drilling, and the like. Is possible.
The cement composition of the present invention may be used in any method when used as a cementing composition for oil wells or gas wells. For example, two-plug cementing, inner string cementing, multistage cementing, liner cementing It is possible to adopt a known method such as the above or a method obtained by modifying them as necessary.
When the cement composition of the present invention is used as a cementing composition for oil wells or gas wells, the cement composition is used to fix the casing pipe by filling the gap with the outer layer of the casing pipe inserted into the well. It can be used for primary cementing and repair cementing for the purpose of subsequent repairs. When the cement composition of the present invention is used for primary cementing, for example, it is possible to prevent the formation fluid from moving between a plurality of formations. Further, the casing pipe can be sufficiently fixed.
When using the cement composition of the present invention, the amount of water used is arbitrary. For example, when used as a cementing composition for oil wells or gas wells, the water cement ratio (W / C ratio) is 30 to 30. About 150% is preferable. A cement slurry containing the cement composition of the present invention and water and having a water-cement ratio of 30 to 150% can be suitably used for cementing for oil wells or gas wells.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

<Measurement of weight average molecular weight and number average molecular weight>
The weight average molecular weight and number average molecular weight of the polymer were measured using GPC (gel permeation chromatography) under the following conditions.
Measuring apparatus: HLC-8320GPC manufactured by Tosoh Corporation
Detector: RI
Column: Shodex Asahipak GF-310-HQ, GF-710-HQ manufactured by Showa Denko KK
Column temperature: 40 ° C
Flow rate: 0.5 mL / min
Calibration curve: POLYACRYLIC ACID STANDARD made by Soka Science Co., Ltd.
Eluent: 0.1N sodium acetate aqueous solution

<Measurement of polymer aqueous solution, monomers in polymer composition>
The monomer was measured using liquid chromatography under the following conditions.
Measuring device: Waters Alliance e2695 system detector: Waters UV detector 2489 UV / Vis detector Column: Showa Denko Co., Ltd. SHODEX RSpak DE-413
Column temperature: 35.0 ° C
Flow rate: 1.0 ml / min
Eluent: 0.1% by mass phosphoric acid aqueous solution

<Measurement of solid content>
In an oven heated to 120 ° C., 1.0 part by mass of the polymer composition and 2.0 parts by mass of water were left to stand for 2 hours for drying treatment. From the weight change before and after drying, the solid content (%) and the volatile component (%) were calculated.

<Measurement of thermal decomposition temperature>
First, the polymer composition was pulverized under the following conditions.
1 part by mass of the polymer aqueous solution was weighed in an aluminum cup and vacuum dried (1.33 hPa (1 mmHg), 50 ° C., 8 hours). Thereafter, the polymer was pulverized in a mortar to obtain a powdered polymer.
The thermal decomposition temperature of the obtained powder polymer was measured using a thermogravimetric analysis-differential thermal analysis (TG-DTA) apparatus under the following conditions. As shown in FIG. 1, the temperature at the point where the tangent line of the TG curve where the initial weight gradually decreases and the tangent point of the inflection point of the TG curve where the weight decreases rapidly on the high temperature side is expressed as the pyrolysis temperature T (° C. ).
Measuring device: TG-DTA2000SR manufactured by Bruker AXS
Temperature range: 30-500 ° C
Temperature increase rate: 10 ° C / min
Circulating gas: Nitrogen 50ml / min
Weighing: 3-15mg

<Measurement of cure retardation>
The cure retardancy of the cement composition was measured using an isothermal calorimeter device under the following conditions, and the time of the secondary hydration peak was calculated. As the secondary hydration peak time increases, the cure delay is higher.
Isothermal calorimeter: TAM AIR manufactured by Thermometric
Cement: Oil well cement OWC-G manufactured by Ube Mitsubishi Cement Co., Ltd.
Water addition amount: 44% by mass / cement polymer addition amount: 0.3% by mass / cement measurement temperature: 20 ° C.

<Production Example 1>
In a 2.5 L capacity SUS316 separable flask equipped with a thermometer, reflux condenser, and stirrer, 140 parts by mass of ion-exchanged water, 40% by mass, sodium allyloxy-2-hydroxy-1-propanesulfonate, aqueous solution 266 parts by mass (hereinafter also referred to as “40% HAPS”) was charged. Thereafter, while stirring the aqueous solution in the polymerization kettle, the temperature of the aqueous solution was raised to reflux with an external jacket.
Next, 250 parts by mass of 80% by mass acrylic acid aqueous solution (hereinafter also referred to as “80% AA”) for 90 minutes, 40% HAPS 266 parts by mass for 60 minutes, 1% by mass sodium hypophosphite aqueous solution (hereinafter, 11 parts by weight (also referred to as “1% SHP”) for 90 minutes, 18 parts by weight of 15% by weight aqueous sodium persulfate (hereinafter also referred to as “15% NaPS”) for 55 minutes, and then 63 parts by weight for 55 minutes The ink was dropped from the tip nozzle through separate supply paths at two supply speeds. The dropping of each component was continuously performed at a constant dropping rate except for 15% NaPS.
After completion of the dropwise addition, the reaction solution was kept at the refluxing temperature for an additional 10 minutes to complete the polymerization. Thus, the copolymer composition (polymer composition (1)) of the present invention was obtained (the copolymer contained is referred to as polymer (1)).
In addition, it was confirmed by ³¹ P-NMR that a hypophosphorous acid (salt) group (sodium hypophosphite group) was introduced into the polymer (1).

<Production Example 2>
A copolymer composition (polymer composition (2)) was obtained in the same manner as in Production Example 1 except that the polymerization conditions were changed to those described in Table 1. (The copolymer contained in the polymer (2 )).
In addition, “2% SHP” in Table 1 represents a 2 mass% sodium hypophosphite aqueous solution. It was confirmed by ³¹ P-NMR that a hypophosphorous acid (salt) group (sodium hypophosphite group) was introduced into the polymer (2).

<Production Example 3>
A copolymer composition (polymer composition (3)) was obtained in the same manner as in Production Example 1 except that the polymerization conditions were changed to those described in Table 1. (The copolymer contained in the polymer (3 )).
In addition, it was confirmed by ³¹ P-NMR that a hypophosphorous acid (salt) group (sodium hypophosphite group) was introduced into the polymer (3).

<Production Example 4>
271 parts by mass of ion-exchanged water was charged into a 2.5 L SUS316 separable flask equipped with a thermometer, a reflux condenser, and a stirrer. Then, it heated up until it refluxed with an external jacket, stirring the aqueous solution in a superposition | polymerization kettle.
Next, a 45% by weight sodium hypophosphite aqueous solution (hereinafter referred to as a 50% by weight sodium hypophosphite aqueous solution at a feed rate of two stages, ie, 80% AA 526 parts by weight, 180% 40% HAPS 175 parts by weight, and then 524 parts by weight 120 minutes. (Also referred to as “45% SHP”) 55 parts by weight for 180 minutes, 15% NaPS by 90 parts by weight and 130 parts by weight, followed by 100 parts by weight for 70 minutes through two separate feed speeds. It dripped from the nozzle. The dropping of each component was continuously performed at a constant dropping rate except for 40% HAPS and 15% NaPS.
After completion of the dropwise addition, the reaction solution was kept at the refluxing temperature for an additional 10 minutes to complete the polymerization. Thus, a copolymer composition (polymer composition (4)) of the present invention was obtained (the copolymer contained is referred to as polymer (4)).
In addition, it was confirmed by ³¹ P-NMR that a hypophosphorous acid (salt) group (sodium hypophosphite group) was introduced into the polymer (4).

<Production Example 5>
215 parts by mass of ion-exchanged water was charged into a 2.5 L SUS316 separable flask equipped with a thermometer, a reflux condenser, and a stirrer. Thereafter, while stirring the aqueous solution in the polymerization kettle, the temperature of the aqueous solution was raised to reflux with an external jacket.
Next, 250 parts by mass of 80% AA for 90 minutes, 506 parts by mass of 40% 2-acrylamido-2-methylpropanesulfonic acid aqueous solution (hereinafter also referred to as “40% AMPS”) for 90 minutes, and 48% by mass hydroxylation 81 parts by mass of an aqueous sodium solution for 90 minutes, 11 parts by mass of a 1% by mass sodium hypophosphite aqueous solution (hereinafter also referred to as “1% SHP”) for 90 minutes, and 43 parts by mass of 15% NaPS for 110 minutes, It dropped from the tip nozzle through a separate supply path. The dropping of each component was continuously performed at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at the refluxing temperature for an additional 10 minutes to complete the polymerization. Thus, a copolymer composition (polymer composition (5)) of the present invention was obtained (the copolymer contained is referred to as polymer (5)).
In addition, it was confirmed by ³¹ P-NMR that a hypophosphorous acid (salt) group (sodium hypophosphite group) was introduced into the polymer (5).

<Production Example 6>
530 parts by mass of ion-exchanged water was charged into a 2.5 L SUS316 separable flask equipped with a thermometer, a reflux condenser, and a stirrer. Thereafter, while stirring the aqueous solution in the polymerization kettle, the temperature of the aqueous solution was raised to reflux with an external jacket.
Next, 80% AA 360 parts by mass was dropped from the tip nozzle for 75 minutes and 15% NaPS 21 parts by mass for 90 minutes through separate supply paths. The dropping of each component was continuously performed at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at the refluxing temperature for 30 minutes to complete the polymerization, thereby completing the polymerization. In this way, a comparative polymer composition (comparative polymer composition (1)) was obtained (the contained polymer is referred to as comparative polymer (1)).
The measurement results of the polymers (1) to (5) and the comparative polymer (1) of the present invention are summarized in Tables 2 to 4.

<Examples 1-5, Comparative Examples 1-3>
The obtained polymers (1) to (5), comparative polymer (1), and lignin sulfonic acid were measured for the thermal decomposition temperature by the method described above. Furthermore, the curing retardancy of the cement compositions to which the polymers (1) to (5), the comparative polymer (1), and lignin sulfonic acid were added was evaluated by the method described above. In the evaluation of the retarding property, the cement composition not added with the polymer was also evaluated. These results are shown in Table 5 and FIGS.

From the results shown in Table 5, FIG. 1 and FIG. 2, it has been clarified that the polymer according to the present invention has both a high thermal decomposition temperature and a curing retardancy. Such a polymer according to the present invention can exhibit sufficient curing retardation even at high temperatures.

Claims (7)

A cement composition comprising a polymer having a carboxylic acid (salt) group having a thermal decomposition temperature of 250 ° C. or higher, and cement. The said polymer contains the structural unit derived from the (meth) acrylic acid (salt), and the structural unit derived from the monomer which has a sulfonic acid (salt) group, The Claim 1 characterized by the above-mentioned. Cement composition. The polymer contains 5 to 50 mol% of structural units derived from a monomer having a sulfonic acid (salt) group with respect to a total of 100 mol% of structural units derived from the monomer. The cement composition according to claim 2. The cement composition according to claim 1, wherein the cement is an oil well cement. The cement composition according to any one of claims 1 to 4, wherein the cement composition is used for cementing oil wells or gas wells. A cement curing retarder comprising a polymer having a carboxylic acid (salt) group having a thermal decomposition temperature of 250 ° C. or higher. The said polymer contains the structural unit derived from the (meth) acrylic acid (salt), and the structural unit derived from the monomer which has a sulfonic acid (salt) group, The Claim 6 characterized by the above-mentioned. Cement hardening retarder.

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