JP2018123279A - Deterioration inhibitor and deterioration inhibition method of drilled mud - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a drilling fluid deterioration inhibitor capable of suppressing hydration and swelling of mixed clay by addition to drilling fluid, suppressing an increase in viscosity of the drilling fluid and reducing specific gravity, and using the same. Provided is a method for suppressing deterioration of the existing drilling fluid. A copolymer containing a compound (A) which is (meth) acrylamide and at least one compound (B) selected from (meth) acrylic acid and a salt thereof as a constituent monomer is contained. The ratio of the compound (B) to the total of the compound (A) and the compound (B) is 10 to 90 mol%, and the intrinsic viscosity of the copolymer in an aqueous solution at 30 ° C. is 0.5 to 10.0 dL /. An agent for suppressing deterioration of excavated muddy water, which is g, and a method for suppressing deterioration of excavated muddy water using the same. [Selection diagram] None

Description

  The present invention relates to a technology for suppressing deterioration during use of drilling mud in civil engineering excavation work, and more particularly to a deterioration inhibitor for drilling mud and a method for suppressing deterioration of drilling mud using the same.

  In underground excavation work such as underground underground wall construction, pile construction, boring construction, shield construction, etc., there is a construction method using excavated mud water to stabilize the excavation groove wall and promote the discharge of excavated sediment. The drilling mud is required to have functions such as stabilization of the drilling groove wall, good replacement with concrete, and good transportability of drilling sediment particles.

  A stabilization liquid, which is a kind of drilling mud, is generally prepared by mixing bentonite, carboxymethylcellulose (hereinafter abbreviated as CMC), a dispersant, and the like with bentonite as a main component. . As the excavation work proceeds, the stabilizing liquid is supplied to the excavation groove, and is discharged from the excavation groove by a pump together with the excavation soil. And it transfers to a collection tank through the processing process with a sediment separator, a circulation tank, a decanter, etc. If the drilling mud recovered in the recovery tank is determined to be reusable as a result of the quality test, it is supplied again to the drilling groove and used.

  However, when the excavated soil contains a large amount of fine particles such as clay and silt, the clay is not sufficiently removed even by a decanter, and hydrates and swells in the excavated mud and changes in specific gravity and viscosity. Along with this, the drilling mud may deteriorate to such an extent that the above function cannot be performed. Such a drilling mud is also adjusted while checking the quality because it affects the safety of drilling work and delays in the construction period. If it is determined that it cannot be reused, it is treated as a waste liquid. An increase in drilling mud that has deteriorated due to hydration and swelling causes an increase in work and cost for the waste liquid treatment, and an increase in time and cost for producing a new stable liquid.

On the other hand, quality control of a stable liquid on site is mainly performed by measurement tests such as specific gravity and viscosity (funnel viscosity). Conventionally, CMC, a dispersant, sodium carbonate, water, and the like, which are constituents of a stabilizing liquid, have been appropriately added and adjusted as necessary so as to satisfy these control standard values. Alternatively, an attempt has been made to remove the mixed clay, which is a cause of deterioration of the drilling mud, by adding a chemical separately.
However, in order to make adjustments for each quality control item of the stabilizing solution, it is complicated to add the specified component after specifying the addition amount of the predetermined component.

  In response to this, for example, Patent Document 1 discloses a polymer containing acrylamide and acrylic acid as a constituent monomer in a predetermined ratio as a stabilizing liquid that easily maintains specific gravity, viscosity, yield value, gel strings, and the like suitable for excavation. A stabilizing solution containing is disclosed. Specifically, a polymer having acrylamide, sodium acrylate, and sodium acrylamide propanesulfonate as constituent monomers and having a weight average molecular weight of 2 million in terms of polyethylene oxide is adjusted so that the concentration in an aqueous solution is 0.5%. Examples added to undisturbed clay are described.

JP 10-158636 A

  In the said patent document 1, when the said polymer is added to undisturbed clay, the dispersion | distribution inhibitory effect of clay is large and B-type viscosity falls. However, although the undisturbed clay particles have a particle size of less than 20 μm, the particles having a particle size of 2 μm or more are 94% by mass, and the particles having a particle size of less than 2 μm are 6% by mass. In actual excavation work, excavated earth and sand often contain finer and more highly swellable clay such that particles having a particle size of less than 2 μm exceed 20% by mass.

  In such a case, the stability liquid with a high molecular weight polymer as described in Patent Document 1 has a tendency to rapidly increase in viscosity, and it cannot always be said that deterioration of drilling mud can be sufficiently suppressed. It was. In particular, when the funnel viscosity increases, the sedimentation property of the clay particles in the drilling mud decreases, so that other quality control items do not satisfy the management standard value, and the drilling mud deteriorates significantly. In addition, the polymer described in Patent Document 1 has a weight average molecular weight exceeding 3.5 million determined from the intrinsic viscosity in an aqueous solution at 30 ° C.

  The present invention has been made to solve such a technical problem. By adding to the drilling mud, the hydration swelling of the mixed clay is suppressed, and the viscosity increase of the drilling mud is suppressed and the specific gravity is reduced. An object of the present invention is to provide a drilling mud deterioration inhibitor that can be reduced, and a drilling mud deterioration suppressing method using the same.

  The present invention has found that the properties of drilling mud can be maintained well by adding a polymer agent made of a copolymer having a predetermined constituent monomer and having a predetermined intrinsic viscosity to the drilling mud. It was made based on.

That is, the present invention provides the following [1] to [3].
[1] A copolymer containing a compound (A) that is (meth) acrylamide and at least any one compound (B) selected from (meth) acrylic acid and a salt thereof as a constituent monomer. The ratio of the compound (B) to the total of the compound (A) and the compound (B) is 10 to 90 mol%, and the intrinsic viscosity of the copolymer in an aqueous solution at 30 ° C. is 0.5 to 10. Degradation inhibitor of drilling mud that is 0 dL / g.
[2] A method for suppressing deterioration of drilling mud during excavation work, wherein the deterioration inhibitor described in [1] is added to at least one of the stable liquid plant and the stable liquid circulation facility. Muddy water deterioration control method.
[3] The above-described deterioration inhibitor is added to the drilling mud so that the amount of the copolymer added to the clay mixed in the drilling mud is 0.1 to 1.0% by mass. [2] The method for suppressing deterioration of excavated mud according to [2].

By adding the drilling mud deterioration inhibitor of the present invention to the drilling mud, the hydrated swelling of the mixed clay is suppressed, and the viscosity increase of the drilling mud can be suppressed and the specific gravity can be reduced.
According to the drilling mud deterioration prevention method of the present invention using the deterioration inhibitor, the drilling mud reuse frequency can be increased, and accordingly, the amount of waste liquid is reduced and a newly prepared stable liquid The amount of use can be reduced. Furthermore, since the deterioration of the quality of the drilling mud is suppressed, it can contribute to the improvement of the safety of the drilling work.

  The drilling mud deterioration inhibitor and the drilling mud deterioration suppressing method using the same will be described in detail below.

[Degradation inhibitor of drilling mud]
The degradation inhibitor for drilling mud according to the present invention comprises a compound (A) that is (meth) acrylamide and at least one compound (B) selected from (meth) acrylic acid and salts thereof. It contains a copolymer to be included as a monomer. And the ratio of the compound (B) with respect to the sum total of the compound (A) and the compound (B) in the said copolymer is 10-90 mol%. The copolymer is characterized by having an intrinsic viscosity in an aqueous solution at 30 ° C. of 0.5 to 10.0 dL / g.
The polymer agent by such a copolymer exhibits an excellent deterioration suppressing effect against drilling mud.

The compound (A) which is a constituent monomer of the copolymer is (meth) acrylamide.
In addition, "(meth) acryl" said by this invention means that acryl or methacryl (it is also mentioned methacryl) may be sufficient. These may be either one or both. That is, the compound (A) is at least one selected from acrylamide and methacrylamide.

  On the other hand, the compound (B) which is a constituent monomer of the copolymer is at least one selected from (meth) acrylic acid and salts thereof. These compounds may be used alone or in combination of two or more. More preferably, at least one selected from sodium acrylate and potassium acrylate is preferable from the viewpoint of dispersibility of the polymer agent by the copolymer.

The content of the compound (B) in the copolymer is based on the total of the compound (A) and the compound (B) from the viewpoint of the balance between the aggregation performance of the compound (A) and the dispersion performance of the compound (B). , 10 to 90 mol%, preferably 11 to 80 mol%, more preferably 50 to 80 mol%.
When the content of the compound (B) is less than 10 mol%, clay particles are aggregated, and the drilling mud may be gelled to cause an increase in viscosity. On the other hand, when it exceeds 90 mol%, sufficient cohesiveness with respect to the mixed clay in the drilling mud cannot be obtained, and the specific gravity of the drilling mud increases.

The constituent monomers in the copolymer are preferably only the compounds (A) and (B), but in a range that does not hinder the function of the deterioration inhibitor that adjusts the specific gravity and viscosity of the drilling mud, the compound (A) and Constituent monomers other than (B) may be included. Examples of such a constituent monomer include sulfonic acid group-containing compounds such as 2- (meth) acrylamide-2-methylpropanesulfonic acid and salts thereof.
The content of constituent monomers other than the compounds (A) and (B) in the copolymer is preferably 10 mol% or less, more preferably based on the total of all constituent monomers of the copolymer. 5 mol% or less.

The copolymer has an intrinsic viscosity in an aqueous solution at 30 ° C. of 0.5 to 10.0 dL / g, preferably 0.7 to 8.0 dL / g, more preferably 1.0 to 4.0 dL / g. It is.
If it is a polymer agent with a copolymer having such an intrinsic viscosity, it is possible to suppress the increase in the viscosity of the drilling mud, and at the same time, the decrease in the specific gravity is also suppressed, effectively preventing the deterioration of the drilling mud. Can do.
When the intrinsic viscosity is less than 0.5 dL / g, sufficient cohesiveness with respect to the mixed clay in the drilling mud cannot be obtained. On the other hand, if it exceeds 10.0 dL / g, the drilling mud may be gelated even if a small amount of the deterioration inhibitor is added.
In addition, intrinsic viscosity shall be calculated | required by the method as described in the Example mentioned later.

The method for producing the copolymer is not particularly limited, and can be performed by a known method. For example, the constituent monomer of the copolymer is added to an aqueous solvent such as water or alcohol, a polymerization initiator or the like is added, and the temperature is 20 to 150 ° C. under normal pressure or pressure for 2 to 5 hours. It can be produced by a solution polymerization method in which copolymerization is performed.
Moreover, as said copolymer, you may use a commercial item, for example, it is a commercially available (meth) acrylamide * sodium (meth) acrylate copolymer, Comprising: The intrinsic viscosity in 30 degreeC aqueous solution is 0.00. What is 5-10.0 dL / g is used suitably.

  The deterioration inhibitor is preferably a liquid agent, more preferably in the form of an aqueous solution or a water-based emulsion, from the viewpoint of uniformly mixing in the drilling mud. The copolymer emulsion after aqueous solution polymerization can be used as it is as a deterioration inhibitor. The concentration of the copolymer in water or in the water system is preferably from 2 to 35% by mass, more preferably from 2 to 25% by mass from the viewpoint of uniform mixing in drilling mud, ease of work of addition, and the like. %, More preferably 15 to 25% by mass. If the concentration of the copolymer is 2% by mass or more, the addition amount of the deterioration inhibitor can be suppressed, and equipment such as a chemical tank can be made compact. Moreover, if it is 35 mass% or less, it is easy to handle without causing gelation.

  The deterioration inhibitor may contain an additive component other than the copolymer as necessary, as long as the effects of the present invention are not impaired.

[Drilling mud water degradation control method]
The method for suppressing deterioration of drilling mud according to the present invention is a method for suppressing deterioration of drilling mud during excavation work. And the said deterioration inhibitor is added to at least 1 place of a stable liquid plant and a stable liquid circulation installation. When added to any of these locations, the drilling mud deterioration suppression effect by the addition of the deterioration inhibitor of the present invention is exhibited.
In the excavation work, the work can be advanced without requiring any change in the operation from the normal process, except that the deterioration inhibitor is added to the excavation mud at the predetermined location.

The degradation inhibitor may be added before or after the production of a stabilizing liquid, which is a new liquid of drilling mud, before the stabilizer is used for excavation work, or in addition, excavation in which clay is mixed during excavation work. It may be added to the muddy water. The addition location is preferably one of a stable liquid preparation mixer, a good liquid tank, a recovery tank, a decanter inlet, between the decanter outlet and the recovery tank, and between the recovery tank and the good liquid tank. . Among these, it may be one place or two places or more. Among these, from the viewpoint of easy calculation of the required addition amount of the deterioration inhibitor, it is preferably any one of a stabilizer preparation mixer, a good solution tank, a recovery tank, and a decanter inlet. In particular, it is preferably a decanter inlet, and is gently stirred for about 1 to 90 minutes, more preferably about 1 to 30 minutes.
In addition, the composition of the stabilizing liquid that is a new liquid of drilling mud is not particularly limited, and may be that of a composition generally used for excavation work. For example, a mixed liquid of 100 parts by weight of water, 1 to 10 parts by weight of bentonite, and 0 to 1 part by weight of CMC is included. In addition, 0 to 1 part by weight of a dispersant and 0 to 1 of sodium carbonate as an ion sequestering agent are included. What added the mass part is also used widely.

The addition amount of the deterioration inhibitor is appropriately set according to the amount of clay mixed in the drilling mud and changes in properties, but the amount of the copolymer is 0.1% with respect to the clay mixed in the drilling mud. It is preferable to be set to ˜1.0% by mass. More preferably, it is 0.2-1.0 mass%, More preferably, it is 0.3-1.0 mass%.
When the amount of the copolymer is less than 0.1% by mass, the specific gravity reduction effect cannot be obtained sufficiently. On the other hand, when it exceeds 1.0 mass%, the inhibitory effect of the viscosity increase of drilling mud is not fully acquired, the sedimentation of clay particles is prevented, and the sufficient reduction effect of specific gravity is no longer acquired.
The amount of clay contained in the drilling mud is obtained by estimating from the specific gravity of the drilling mud to which the deterioration inhibitor is to be added. At the site of excavation work, in the drilling mud evaluation test, the amount of mixed clay is usually determined simply from the measured value of specific gravity, which is a management item.

  When the deterioration inhibitor is added to a stable liquid that is a new liquid for drilling mud, it should be added so that the amount of the copolymer is 0.005 to 0.2% by mass with respect to the stable liquid. Is more preferable, 0.01 to 0.15% by mass, still more preferably 0.05 to 0.1% by mass. When the amount of the copolymer is 0.005% by mass or more, the deterioration of the stabilizing liquid can be sufficiently suppressed. Moreover, if it is 0.2 mass% or less, it can be set as the stable liquid of suitable viscosity on handling.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by the following Example.
The various polymer agents shown in the following examples and comparative examples were subjected to an evaluation test for suppressing deterioration of drilling mud using simulated drilling mud.

[Drilling mud sample liquid]
The additives used in the drilling mud sample solution are as follows.
・ Bentonite ("Kunigel V2", manufactured by Kunimine Industry Co., Ltd.)
・ CMC ("DK High Polymer 200", manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
・ Clay A (particle size of less than 2 μm: 41% by mass, particle size of 2 μm or more and less than 5 μm: 9% by mass, particle size of 5 μm or more: 50%)
・ Clay B (particle size of less than 2 μm: 20% by mass, particle size of 2 μm or more and less than 5 μm: 10% by mass, particle size of 5 μm or more: 70%)
The particle sizes of clays A and B are values measured by a laser diffraction particle size distribution measuring device.

[Evaluation test]
(1) After adding 20 g of bentonite to a poly beaker containing 1 L of pure water and stirring for 10 minutes, 2 g of CMC was added and stirred for 10 minutes.
(2) A predetermined amount (0.1 to 2.0 g) of various polymer agents shown in the following Examples and Comparative Examples was added to another poly beaker containing 1 L of pure water, and stirred for 30 minutes.
(3) Each liquid prepared in (1) and (2) was transferred to a 2 L poly beaker, mixed, stirred for 5 minutes, and then allowed to stand for 24 hours to completely dissolve CMC.
(4) 200 g of clay A and B were added thereto, and the mixture was stirred at 300 rpm for 90 minutes, then passed through a sieve having an opening of 150 μm, and the passed liquid was evaluated and measured for specific gravity and viscosity by the method described below. went. In addition, even when the polymer agent was not added, the specific gravity was evaluated and measured for comparison.
(5) The solution after the measurement was returned to the 2 L polybeaker, and the above operation (4) was repeated twice.
The addition amount of the polymer agent with respect to the clay content (clays A and B) was changed in the range of 0.02 to 1.0% by mass, and the specific gravity and viscosity were evaluated and measured for each addition amount.

(Evaluation item)
<Specific gravity>
A funnel viscometer container (capacity 500 mL) was filled with pure water, and the weight of pure water was weighed. Similarly, the container was filled with the measurement sample solution, and the weight of the measurement sample solution was weighed. The specific gravity was calculated by dividing this weight by the weight of the pure water.
When the specific gravity was lower than that of the comparative control (no polymer agent added), it was determined that the specific gravity reduction effect was obtained.
<Viscosity (Funnel viscosity)>
The bottom hole of the funnel viscometer was closed with a finger, and 500 mL of the measurement sample solution was poured. The container was set under the funnel viscometer, and the time from when the finger was removed from the bottom hole until the measurement sample solution in the funnel viscometer container finished flowing was measured. This time was defined as the funnel viscosity.
In view of the management standards at the excavation site, when the funnel viscosity was 35 seconds or less, it was determined that the effect of suppressing the viscosity increase was obtained.

[Polymer agent]
As a polymer agent, an acrylamide / sodium acrylate copolymer having an intrinsic viscosity and a weight average molecular weight as shown in Table 1 below was prepared. The intrinsic viscosity and weight average molecular weight of each of these polymer agents were determined as follows.

(Intrinsic viscosity)
A sample solution having a polymer concentration in five stages of 0.02 to 0.08% (mass / volume) of each polymer agent was prepared.
10 ml of the sample solution was injected into the Ubbelohde viscometer set in a thermostat at 30 ° C. with a whole pipette. The time required for the liquid level of the sample liquid to rise 5 to 10 mm above the upper reference line of the measurement sphere and then let it flow naturally, and the liquid level passes between the upper and lower reference lines of the measurement sphere. Was measured. This operation was repeated three times for each polymer concentration, and the average value t of each measured value was determined. The same measurement was performed on the 1N sodium chloride aqueous solution, and the blank value t ₀ was set.

The following relational expressions hold for the relative viscosity η _rel , the specific viscosity η _sp, and the reduced viscosity η _red .
Relative viscosity η _rel = t / t ₀
Specific viscosity η _sp = (t−t ₀ ) / t ₀ = η _rel −1
Reduced viscosity η _red = η _sp / c = (t−t ₀ ) / (t _{0 ·} c)
(Where c is the polymer concentration)

Therefore, the relationship between η _sp / c and ln η _rel / c is plotted, an intercept of a regression line (approximate line) is obtained based on the following relational expression, and this value is defined as intrinsic viscosity [η].

(Weight average molecular weight)
The weight average molecular weight Mw was calculated from the viscosity formula of polyacrylamide polymer: [η] = 3.73 × 10 ⁻⁴ Mw ^0.66 using the value of the intrinsic viscosity [η] determined above (“radical polymerization”). Handbook ", NTS Corporation, p.558 (1999)).

  Table 1 below collectively shows the intrinsic viscosity, the weight average molecular weight, and the content of sodium acrylate in all the constituent monomers of the copolymer of the polymer agent of each of the above Examples and Comparative Examples.

In Examples 1-6, when the addition amount of the polymer agent with respect to a clay content was 0.1-1.0 mass%, it was recognized that a viscosity increase was suppressed and specific gravity reduced.
About the comparative example 1, even if the addition amount was less than 0.1 mass%, the measurement sample liquid gelatinized. As for Comparative Example 2, when the addition amount was 0.2% by mass, the viscosity of the measurement sample solution was high, and when the addition amount was 0.4% by mass, the measurement sample solution was gelled. In Comparative Example 3, as in Comparative Examples 1 and 2, the intrinsic viscosity was high, and when the addition amount was 0.2% by mass or more, the viscosity tended to increase rapidly. For this reason, it is difficult for Comparative Examples 1 to 3 to set an appropriate range of the addition amount, and lacks practicality.
The polymer agent of Comparative Example 4 functions as a dispersant, and no increase in viscosity was observed. However, as the addition amount increased, the dispersibility of the clay content increased and the specific gravity tended to increase. .

Claims (3)

  Containing a copolymer comprising, as a constituent monomer, compound (A) which is (meth) acrylamide and at least any one compound (B) selected from (meth) acrylic acid and salts thereof, The ratio of the said compound (B) with respect to the sum total of (A) and the said compound (B) is 10-90 mol%, and the intrinsic viscosity in 30 degreeC aqueous solution of the said copolymer is 0.5-10.0 dL / g. Deterioration inhibitor for drilling mud.   A method for suppressing deterioration of drilling mud during excavation work, wherein the deterioration inhibitor according to claim 1 is added to at least one of a stable liquid plant and a stable liquid circulation facility. Method.   The said deterioration inhibitor is added to the said drilling mud so that the addition amount of the said copolymer with respect to the clay mixed in the drilling mud may be 0.1-1.0 mass%. To suppress the deterioration of drilling mud.