JPH064845B2 - Dispersant for stable liquid drilling method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a stable liquid excavation method volume dispersant used when excavating a formation.

Carboxymethylcellulose sodium (hereinafter CMC
, Etc.) a bentonite suspension containing a water-soluble polymer compound, a so-called bentonite stabilizing solution, is filled in the excavated part to prevent the wall from collapsing, and then concrete is placed to form a continuous continuous wall or The stable liquid excavation method for constructing foundation mines is currently used on the other side.

Since bentonite is sensitive to inorganic electrolytes, bentonite stabilizer tends to agglomerate or gel due to the inclusion of sodium chloride accompanying the excavation of ground containing seawater or the inclusion of cement during concrete placement. .

The bentonite stabilizer that has deteriorated in this way is the stable liquid on the borehole wall that is the stable film (mud cake) on the borehole wall.
Since it is inferior in formability and the ability to prevent wall collapse is reduced and it becomes unusable as it is, it is necessary to discard or recycle it.

There are methods such as natural sedimentation, water dilution, addition of a dispersant, etc. for regenerating the soil-sand stabilized liquid.

The CMC added to the stabilizing solution has a protective colloid ability and has an effect of inhibiting sedimentation of sediment, and since the viscosity becomes high due to the inclusion of sediment, the sedimentation efficiency is extremely low and stable by the natural sedimentation method. Difficult to regenerate the liquid.

It is easy to reduce the specific gravity and viscosity of the stabilizing solution by diluting with water, but bentonite and CMC can be diluted with water.
It is not preferable because it also lowers the concentration, and the ability to prevent wall collapse, which is a stable liquid function, also decreases.

A method of adding a dispersant to the regeneration of a stable liquid whose specific gravity and viscosity have increased due to the mixed soil and reducing its viscosity by the peptizing action of the dispersant and accelerating the separation of the mixed soil and sand is considered.

Inorganic polyphosphates and sodium carbonates are known as dispersants for stabilizing liquids, and nitrohumates, lignin sulfonates, low-polymerization polyacrylates, etc. are known as organic-based dispersants. Acrylate has a high effect as a dispersant and is usually used in a liquid form containing 20 to 40% by weight of the active ingredient.

In recent years, large-scale civil works such as nuclear power plants, LNG underground tanks, and Kaifu crossing bridges have increased, and the number of works that require a large amount of stabilizing liquid has increased. For this reason, a stable liquid automatic manufacturing machine having an automatic material supply function and having a capacity of 10 to 100 m ^{3 /} hour is being widely used.

Bentonite, CMC, and a dispersant are mainly used as materials for the stabilizing solution. Of these, bentonite CMC is in powder form, and the dispersant is also preferably in powder form in consideration of the necessity of automatic supply, storage and handling.

The low-polymerization degree polyacrylic acid salt can be produced by a method in which it is dried by heating, reduced pressure, etc., and then crushed or spray-dried. It is difficult to use in an automatic stabilizer manufacturing machine because it easily absorbs moisture, becomes sticky, and easily causes caking during storage, which makes storage management difficult.

As a countermeasure against this, a copolymer [salt type] of methacrylic acid, acrylamide, acrylic ester, etc. can be considered.
The hygroscopicity cannot be greatly improved, but on the contrary, it has drawbacks such as dispersion and deterioration of peptizing property.

The present inventors have arrived at the present invention as a result of earnest research to solve these problems. That is, the present invention relates to a powdery (meth) acrylic acid polymer having a degree of polymerization of 20 to 500 or a copolymer of (meth) acrylic acid and another acrylic monomer [content of (meth) acrylic acid 50 Disclosed is a dispersant for a stable liquid excavation method, which comprises an acid type powder product in an amount of at least 1 mol% as an essential component.

Other acrylic monomers include water-soluble monomers,
And water-insoluble monomers, but they can be used if the copolymer is water-soluble. Examples of typical monomers include esters such as acrylamide, methacrylamide, acrylamidomethylpropanesulfonic acid, methyl (meth) acrylate, ethyl (meth) acrylate, and hydroxyethyl (meth) acrylate.

In the case of copolymers with acrylic monomers, (meth)
The content of acrylic acid is more preferably 50 mol% or more. When the content of (meth) acrylic acid is less than 50 mol%, the peptizability for dispersion is lowered.

Further, the degree of polymerization is preferably in the range of 20 to 500, and outside this range, the sufficiently satisfactory dispersion peptizing property of the present invention cannot be achieved.

Although a part of the polymer in the present invention can be used in the form of sodium, potassium, ammonium or amine salt, the hygroscopicity becomes higher as the content of the salt type increases, so the content of the salt type is 50% by weight or less. Is preferred.

The method for producing the polymer in the present invention is produced by polymerizing using a generally-used method for polymerizing an acrylic monomer, followed by dehydration by heating drying, vacuum drying, etc., followed by pulverization or spray drying. be able to.

In the method of using the dispersant for the stabilizing solution drilling method of the present invention, 0.01 to 1.0% by weight is added as a usage amount when the stabilizing solution is produced. In addition, even if the excavated soil is mixed to increase the viscosity, or the stabilizing solution is gelled by cement, 0.01-
It can also be used by adding 1.0% by weight.

Further, it can be mixed with CMC to improve CMC having high salt resistance and high cement resistance, and mixed with bentonite to be applied to production of bentonite having high salt resistance and high cement resistance. Further, it is also effective when used as a dispersant for muddy water in the muddy water shield propulsion method.

The dispersant for the stable liquid drilling method of the present invention may be used in combination with another dispersant, a tripolyphosphate, a hexametaphosphate, a ligulinsulfonate, or a nitrohumate.

INDUSTRIAL APPLICABILITY The dispersant for the stable liquid excavation method of the present invention is a powdered dispersant having a low hygroscopic property and easy to handle, and is a dispersant having good storage stability and excellent dispersion peptizing property.

Next, the present invention will be specifically described with reference to examples.

[%, Parts indicate weight basis] Example 1 (Production of dispersant) 2,2-azobis (2-amidinopropane) dihydrochloride 0 as a polymerization catalyst in a mixed solution of 360 g of acrylic acid and 360 g of ion-exchanged water 0.2 g was added to carry out aqueous solution polymerization to obtain a 50% aqueous solution.

The aqueous solution was vacuum dried and then pulverized to obtain a polyacrylic acid polymer powder product. The average degree of polymerization of this product was 125.

According to the above, a polymer having the composition shown in Table 1 was produced,
The following examples were tested.

Example 2 5 g of the dispersant powder was placed in a glass petri dish having a diameter of 10 cm and allowed to stand in an atmosphere having a temperature of 20 ° C. and a relative humidity of 65%, and the moisture absorption rate was measured. The results are shown in Table 1.

As is clear from Table 1, the product of the present invention has low hygroscopicity,
No change in state was observed even after standing for 24 hours.

The comparative product absorbed moisture remarkably and caking after 24 hours lost the powder fluidity.

The dispersants were all 100 mesh sieves that were passed through and tested.

Example 3 6 parts of Kunigel V ₁ [bentonite: manufactured by Kunimine Industry Co., Ltd.] in 100 parts of water, CMC [viscosity of 1% aqueous solution 1000 cp,
A degree of etherification of 0.65] and a predetermined amount of a dispersant were added, and the mixture was stirred and mixed with a propeller-type stirrer for 20 minutes to prepare a stable solution. This stabilizing liquid contains cohesive soil (water content 56
%) 20 parts and 20 minutes of stirring and mixing to disperse
Further, 0.5 parts of ordinary Portland cement was dispersed in 1 part of water to form a slurry, which was added and stirred for 3 minutes to measure the properties of the stabilizing solution. The results are shown in Table 2.

As is clear from the results shown in Table 2, all the products of the present invention were excellent in the disaggregation and peptization properties, and the amount of water was small and the effects were excellent.

It is considered that this is because the amount of pure dispersant is large because the solid content does not contain Na.

Claims (1)

[Claims] 1. A powdery (meth) acrylic acid polymer having a degree of polymerization of 20 to 500 or a copolymer of (meth) acrylic acid and another acrylic monomer [content of (meth) acrylic acid is 50 mol. % Or more] of the acid type powder product as an essential component.