JPS6223993B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to cementing methods for wells, such as casing cementing, squeeze cementing, liner cementing, and reclamation cementing in drilling methods. In order to obtain sufficiently satisfactory results in these cementing methods in excavation methods, various additives have been conventionally used in cement slurry compositions for cementing.
These additives include cement fast hardening agents, cement slow hardening agents, low specific gravity additives, high specific gravity additives, cement dispersants, dispersing and slow hardening agents, and water retention agents (dehydration reducing agents).
There are different ways to use them depending on the purpose. Then, depending on the wellbore conditions, these additives are appropriately combined to form a cement slurry composition that is most suitable for the wellbore conditions and used for cementing. The present invention provides a cementing method for wells using a cement slurry composition containing polyethyleneimine, a neutralized aqueous salt thereof, or a water retention agent consisting of polyethyleneimine and a sequestering agent. The recent cementing method for wells involves lowering a casing pipe to a predetermined depth within the well, passing it from the ground into the casing pipe, and applying cement slurry (with various additives to cement and water) into the annular gap between the casing pipe and the stratum. The annular cavity is filled with cement slurry starting from the bottom of the wellbore, and the hardened cement slurry fixes the casing pipe in the wellbore to form the inner wall of the wellbore. It protects the Known water retention agents conventionally used in the formulation of cement slurry include bentonite,
Hydroxyethyl cellulose (HEC), etc. Such water retention agents generally have poor heat resistance, and when used in wells with high temperatures, the water retention effect decreases, the amount of water removed during construction increases, and it deteriorates over time. In this case, the quality of the cement slurry changes, that is, its fluidity is impaired, so that satisfactory and complete cementing cannot be achieved. Furthermore, when making cement slurry by dissolving cement in water, the viscosity of the cement slurry increases more than necessary due to the addition of these water retention agents, making it difficult to obtain slurry properties with desired flow characteristics. There is. Therefore, these conventional water retention agents cannot achieve the desired performance in terms of cement slurry properties, and cementing, especially when used in wells with high temperatures, ends in failure, making subsequent boring impossible. In other words, the quality of the water retention agent used during cementing has a significant influence on the success or failure of the well, so water retention is necessary to obtain stable slurry properties that do not change significantly depending on the conditions in the well. There is a strong need to improve the quality of these agents. The present inventors conducted research to improve the water retention agent that has a particularly important influence on the cement slurry composition used in the cementing method as described above, and as a result, discovered a new water retention agent, and developed an in-well cementing method using the same. This led to the invention of That is, the water retention agent used in the present invention is composed of polyethyleneimine or a neutralized aqueous salt thereof, or this and a sequestering agent. This water retention agent is also compatible with polyamines.
A mixture of polyamide, tertiary amine salt polymer, quaternary ammonium salt polymer, etc. can also be used. Polyethyleneimine is obtained by polymerizing ethyleneimine with an acid catalyst such as carbon dioxide, hydrochloric acid, hydrobromic acid, p-toluenesulfonic acid, aluminum chloride, or boron tetrafluoride. In the present invention, those produced industrially by such a method can also be used without any particular problem. Characteristics of the polyethyleneimine used: solid content 30
% aqueous solution viscosity (Brutskfield viscometer 25
℃, 60 rpm), the viscosity range suitable for the water retention agent used in the method of the present invention is 400 to 60 rpm.
It is about 3000 cps, and the more preferable range is about 800 to 2000 cps. When the viscosity of polyethyleneimine is less than 400 cps, the fluidity of the cement mixture is good, but the water retention property tends to be poor, and when it exceeds 3000 cps, good water retention property is obtained, but on the other hand, cement slurry composition The fluidity of the cement is impaired and handling becomes complicated as a cementing method. The neutralized aqueous salt of polyethyleneimine is one that has been neutralized with a neutralizing agent that is compatible with polyethyleneimine. The pH of an aqueous solution of polyethyleneimine itself is usually 10 to 11, and common examples of neutralizing agents used in this case include known inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, as well as acetic acid, oxalic acid,
It is an aqueous salt obtained by neutralizing polyethyleneimine with an appropriate amount of one or more acids selected from commonly known organic acids such as tartaric acid and benzoic acid. Other neutralizing agents are not limited to the above-mentioned inorganic acids and organic acids, but any water-soluble neutralizing agent that is compatible with polyethyleneimine can be used. The pH of the neutralized aqueous salt of polyethyleneimine is preferably 4 or higher, preferably 5 or higher. As mentioned above, the water retention agent used in the in-well cementing method of the present invention is composed of polyethyleneimine or its neutralized aqueous salt, or this and a metal ion sequestering agent. As agents, there are generally known agents that have the ability to bind to metal ions and are effective in inactivating the ions, and agents that have the ability to form water-soluble metal complex salts. Representative examples include ethylenediaminetetraacetic acid (EDTA), N-hydroxyethylethylenediamine N・N′・N″-triacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TIHA), and and other similar compounds thereof.Also, nitrilotriacetic acid, citric acid, gluconic acid, succinic acid,
tartaric acid, malic acid, dipicolinic acid, iminodiic acid,
and other commonly known sequestering agents such as glutamic acid and their salts. Among the various metal ion sequestering agents mentioned above, oxycarboxylic acids such as citric acid and tartaric acid are already known as additives for the purpose of water retention in cement slurry compositions. When these metal ion sequestering agents are used alone, they have various disadvantages and cannot achieve sufficient effects for the purpose of the present invention, but when used in combination with polyethyleneimine etc., they are extremely effective. The water retention effect is significantly improved. The usage ratio of these metal ion sequestering agents, that is, the ratio of polyethyleneimine to metal ion sequestering agent, is preferably in the range of 100:0.5 to 20 parts by weight (solid content weight ratio), and more preferably in the range of 100:2 to 15 parts by weight. . If the compounding ratio of the sequestering agent is less than 0.5, it is difficult to see an improvement in the water retention effect when used in combination.
If it exceeds 20, it will have a negative effect on the strength of the cement mixture after hardening. When these metal ion sequestering agents are used in combination with polyethyleneimine, they can be added to cement slurry in the form of a pre-mixed mixture of polyethyleneimine (aqueous solution) and solid metal ion sequestering agents or those dissolved in water. Alternatively, the polyethyleneimine and the sequestering agent can be added and blended separately, and the effects of the present invention can be obtained by either method. As mentioned above, the water retention agent of the present invention is composed of polyethyleneimine or a neutralized aqueous salt thereof, or a sequestering agent in combination with polyethyleneimine, but a water-soluble polymer compatible with these can also be used in combination. Examples of compatible water-soluble polymers include polyacrylamide homopolymers, acrylonitrile, vinyl acetate, acrylic acid alkyl esters, methacrylic acid alkyl esters, etc. that can be copolymerized with acrylamide and do not impair water solubility. A water-soluble acrylamide copolymer obtained by copolymerizing one or more selected from the following, or acrylic acid or methacrylic acid ester of dimethylaminoethyl, diethylaminoethyl, diethylaminopropyl alone or one of the above monomers, or There are neutralized aqueous salts obtained by copolymerizing two or more types, and cationic water-soluble polymers obtained by converting the above-mentioned tertiary amino esters into quaternized ammonium salts using methyl chloride or benzyl chloride. The polyamines and polyamides used here are all water-soluble derivatives, and water-soluble polyamines are obtained by the condensation reaction of amines and chlorides, such as ethylene diamine or polyalkylene polyamines and ethylene chloride,
It is a reaction product with propylene chloride or epichlorohydrin, and is a polyamine derivative containing a hydroxyl group or an amide group in the amino group. Water-soluble polyamide is a water-soluble polyamide obtained by reacting epichlorohydrin with the product obtained by condensation of adipic acid and diethylenetriamine to introduce a hydroxyl group into the molecule, or by adding dimethylamine or neutralizing amine groups to form a quaternary ammonium salt. polyamide is used. These water-soluble polymers are not expected to be particularly effective as water-retaining agents, but they are added to improve the viscosity and other handling characteristics of the water-retaining agent, and they are added to an extent that does not reduce the effectiveness of the water-retaining agent. Use in combination with the amount of In the present invention, the water retention agent used in the above-mentioned well cementing method is preferably used in an amount of 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, in terms of solid content, based on the cement. If the amount added is less than 0.01% by weight, the effect as a water retention agent cannot be fully demonstrated, and 10% by weight
If it exceeds the amount, it will not be effective depending on the amount and there will be no economic merit.If the amount added is too large, the compressive strength and other properties of the cement will deteriorate, resulting in a brittle solidified cement product. I won't be able to do it. The water retention agent used in the present invention can be used in combination with fast hardening agents, slow hardening agents, low specific gravity additives, high specific gravity additives, dispersants, etc. conventionally used in cement slurry compositions, and can be used in combination with conventional cement slurry compositions. By changing only the water retention agent in the slurry composition, the excellent effects described below can be imparted to the cement slurry composition, resulting in a marked improvement in the well cementing method. The cement used in the present invention includes Portland cement, blast furnace cement, silica cement, alumina cement, iron Portland cement, solid, calcium silicate, and all other cements used in wells. The water retention agent used in the present invention has the following advantages over conventional water retention agents. (1) Good solubility in fresh water and seawater. (2) Excellent dehydration reduction effect even when added in small amounts. (3) It has excellent heat resistance and can be used in a wide temperature range from low to high temperatures. (4) By using it in combination with a dispersant, the consistency (viscosity) of the cement slurry is reduced, and the fluid can be easily adjusted to form a turbulent cement slurry. (5) Adjustment of slurry specific gravity is easy. (6) Easy to handle. Next, the present invention will be explained in detail in Examples. Example 1 100 parts by weight (hereinafter "parts") of class G cement for Portland oil wells, 42 parts of fresh water, and 0.5 part of a naphthalene sulfonic acid dispersant (Nippon Nyukazai Co., Ltd.; trade name: Escor) were mixed in a mixer. Polyethyleneimine (PEI) is used as the water retention agent A of the present invention.
(Solid content 30%, 25℃ viscosity 1480cps) 92% by weight, ethylenediaminetetratetratetraacetic acid soda (EDTA-4Na) 8% by weight (solids content 30%, PH11.3 25℃ viscosity 1400cps) in person
When 1.0, 2.0, 3.0, 4.0 parts were added, and when no water retention agent was added (Comparative Example 1), 40°C, 70
The amount of dehydration was measured at temperatures of 101°C, 133°C. The results are shown in Table-1. In this test, 0.5 parts of a lignin sulfonic acid retardant (trade name, HR-12, manufactured by Halliburton, Inc., USA) was added to each test slurry in order to prevent the slurry from curing.

【table】

[Table] As shown in Table 1, this water retention agent A was found to have a sufficient dehydration reducing effect in the temperature range of 40°C to 133°C. Example 2 100 parts of class G cement for Portland oil wells was mixed with 42 parts of water and 0.5 parts of dispersant Escor in a mixer, and water retention agents A and B of the present invention having different water retention agent components were added to this as a water retention agent. , C, D or conventional product E (hydroxyethyl cellulose; 2% aqueous solution PH7.1, 25°C viscosity 17 cps) was added in the form of 2.0 parts, and the amount of dehydration at 60°C and 86°C was measured.
The results are shown in Table-2.

[Table] Example 3 The compressive strength of cement slurry solidified by the addition of a water retention agent was tested. Mix 100 parts of Portland cement with 42 parts of fresh water and 0.5 parts of dispersant Escor in a mixer, and add water retention agent A in the form of 1.0, 2.0, 3.0, 4.0.
After curing and solidifying, the compressive strength of the solid unit was measured. In addition, measurements were made in the same manner without water retention agent added (Comparative Example 3), and the results are shown in Table 3.
Shown below.

[Table] This compressive strength has a significant effect on fixing the casing pipe and protecting the wellbore, so a moderate strength is required, and the method of the present invention has no adverse effect on this compressive strength. Example 4 100 parts of Portland well class G cement, 44 parts of fresh water and 0.5 parts of dispersant Escor were mixed in a mixer, and this was mixed with water retention agent F (water retention agent component PEI).
Single, 30% solids aqueous solution, PH=10.8, viscosity at 25℃
1080cps) was added in the form of 1.0, 2.0, 3.0, 4.0 parts,
The apparent viscosity of the slurry was measured in each case. In addition, measurements were made in the same manner with no water retention agent added (Comparative Example 4), and the results are shown in Table 4.

[Table] As shown in Table 4, the addition of the water retention agent had no adverse effect on the fluidity of the cement slurry and good results were obtained.

Claims (1)

[Claims] 1 polyethyleneimine or its neutralized aqueous salt,
Alternatively, a cementing method for wells is characterized by using a cement slurry composition containing this and a metal ion sequestering agent as a water retention agent.