JPH111363A - Manufacturing method of cement for geothermal wells - Google Patents

Abstract

(57) [Problem] To be able to maintain excellent desired strength without deterioration even in a long-term high-temperature and high-pressure environment.
A cement clinker carried out from a rotary kiln and having a chemical composition with a CaO / SiO ₂ molar ratio of 0.6 to 2.0 is pulverized while spraying a large amount of water, and the obtained pulverized material is powdered with an Al ₂ O ₃ source. The raw material is Al ₂ O ₃ 5% by weight to 40
% By weight, and watering is
CaO / SiO ₂ molar ratio can also be ground with a large amount of water spray to cement clinker and Al ₂ O ₃ source material having a chemical composition of 0.6 to 2.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a cement for geothermal wells, and more particularly, to a geothermal well having moderate slow-hardening properties and maintaining strength for a long period of time under high temperature and high pressure. The present invention relates to a method for producing a cement for use.

[0002]

2. Description of the Related Art In geothermal resource surveys and geothermal power generation, a well is excavated deep underground. Groundwater or gas inflow into this well or outflow of ejected fluid is shielded to prevent collapse of the well after excavation. In order to prevent this, a steel pipe (casing pipe) having a diameter suitable for the well diameter at that point is usually inserted to a predetermined depth. At that time, in order to fix and protect the casing pipe, an annular portion between the casing pipe and the pit wall is filled with cement slurry and solidified.

[0003] Since such cement is exposed to high temperature and high pressure for a long period of time, it is necessary to maintain its strength even under such conditions. Conventionally, such cement is class G cement or cement. Class J cement (oil well cement specified by the American Petroleum Institute standards) is used, and the former class G cement is mainly 3CaO.
A cement mainly composed of SiO ₂ is used. In the latter class J cement, β-2CaO.Si is mainly used.
A cement comprising a clinker rich in O ₂ and a siliceous substance is used.

Japanese Patent Application Laid-Open No. 58-15049 discloses that
Re burned material of retort residue by-produced during the magnesium metal production 50-90%, wellbore cement composition containing 10 to 45% by weight of siliceous material is described, as an example, SiO ₂ ( 31% by weight), Al ₂ O ₃ (1
_{Wt%), Fe 2 O 3 (} 6 wt%), CaO (57 wt%), MgO (4 wt%), SO ₃ (0.2 wt%),
Others (2.4% by weight) are shown.
Has excellent strength under high pressure.

[0005]

However, class G cement and class J cement as described above contain a siliceous substance for the purpose of high temperature resistance, deterioration resistance and the like. The setting time is short, so that it is necessary to use a large amount of setting retarder in order to extend the setting time,
There was a problem that it was difficult to obtain stable quality.

Further, in a class G cement or a class J cement, in a long-term high-temperature and high-pressure environment, zonotolite is generated in a hardened cement body, and as a result, the strength of the hardened body is reduced and cracks are formed. Is deformed or damaged, which causes the escape of geothermal steam and a decrease in the flow rate of the produced steam, and there is a problem that the casing pipe cannot be protected for a long period of time. In the described cement, the main compound contained in the refired product of the retort residue produced as a by-product during the production of magnesium metal is α'-2CaO.SiO ₂ , and a small amount of β-2CaO.SiO ₂ and CaO.F
are those like e ₂ O ₃ is contained, whether but has excellent strength under high temperature and high pressure, the and strength over a long period of time under high temperature and high pressure environment for the same reason can be maintained Is considered to be another problem.

Therefore, the present inventors have studied various problems with respect to the above-mentioned problems, and aimed at maintaining the strength without deterioration even under a high-temperature and high-pressure environment for a long period of time. While continuing research, Al ₂
The O ₃ was increased, as cement clinker with the inclusion of a large amount of Al ₂ O _3, by a clinker having a slow-curing by grinding from over water to clinker, long-term high temperature and high pressure environment However, they have found that a cement for geothermal wells capable of maintaining a desired strength without deterioration can be produced, and the present invention has been made based on this finding. Accordingly, an object of the present invention is to provide a method for producing a geothermal well cement that can maintain excellent desired strength without deterioration even under a high-temperature and high-pressure environment for a long period of time.

[0008]

SUMMARY OF THE INVENTION The above-mentioned object of the present invention is as follows.
A cement clinker carried out from a rotary kiln and having a chemical composition with a CaO / SiO ₂ molar ratio of 0.6 to 2.0 is pulverized while spraying a large amount of water, and the obtained pulverized material is powdered with an Al ₂ O ₃ source. The raw material is Al ₂ O ₃ 5% by weight to 40
It is achieved by a method for producing a cement for geothermal wells, characterized in that the mixing is carried out in an amount of 1% by weight. As described above, in the method for producing a cement for geothermal wells of the present invention, a cement clinker is pulverized by a finish mill while sprinkling a large amount of water, and the obtained pulverized material is mixed with an Al ₂ O ₃ source material of 5 wt% of Al ₂ O _3. ~ 4
By mixing in an amount of 0% by weight, an excellent effect of obtaining a cement for geothermal wells capable of maintaining a desired strength of a cured product under a high-temperature and high-pressure environment for a long period of time is obtained.

In the present invention, the amount of watering is preferably between 0.8 and 2.0% by weight of the clinker. In addition,
Gypsum or a grinding aid may be appropriately added during grinding in the finishing mill. In another embodiment, in the method for producing a geothermal well cement according to item 1 of the present invention, the CaO / Si
A method characterized by pulverizing a cement clinker having a chemical composition with an O ₂ molar ratio of 0.6 to 2.0 and an Al ₂ O ₃ source material while spraying a large amount of water may be used. Further, in the method for producing a cement for geothermal wells according to the present invention, the relationship between watering and crushing is, when crushing the cement clinker, a method in which a large amount of water is sprinkled on the cement clinker and a sufficient amount of water is applied to the cement clinker in advance. And pulverization method, and any of these can be preferably used, and the former is particularly preferable. In the latter case, the amount of watering and the time from watering to grinding can be appropriately changed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. The method for producing a cement for geothermal wells according to the present invention is carried out from a rotary kiln and has a CaO / SiO ₂ molar ratio of 0.6-2. may be water on cement clinker having the chemical composition of 2.0 was ground while sprinkling water well over by grinding or from the cement clinker, Al ₂ O ₃ source material to the resulting ground product of Al ₂ O ₃ 5% by weight to 4
It is characterized in that it is mixed in an amount of 0% by weight, and there are various kinds of Al ₂ O ₃ source materials. Examples of clinker minerals rich in alumina include calcium aluminate and ayne. Examples of slag include blast furnace slag, high alumina slag, fly ash, and further clays such as bentonite, carion,
Examples thereof include refractory clay, band shale, and the like, and other examples include alunite, feldspar, pottery stone, aluminum dross, and alumina cement. One or more of these can be used as a mixture.

In the method for producing a geothermal well cement of the present invention, the pulverized clinker produced as described above is added to Al ₂ O
_{When the three} source materials are mixed, the mixing amount is such that Al ₂ O ₃ is 5% by weight to 40% by weight based on the clinker pulverized product.
Is intended to apply an amount containing, therefore, the amount of Al ₂ O ₃ source material to be mixed with the clinker grinding material is different depending on the content of Al ₂ O ₃ which is contained in the Al ₂ O ₃ source in the raw materials, using Al _{It is} determined in each case by the source material of ₂ O ₃ . For example, in the case of blast furnace slag, it is sufficient that the content is 16% by weight or more, and in the case of alumina cement, it is preferably 4% by weight to 65% by weight.

In the present invention, CaO / SiO_TwoSource
In this case, cement-based clinker is preferably used.
Among them, CaO / SiO_Two(Molar ratio) 0.6 to 2.0
In the present invention, a cement-based clinker having a chemical composition
preferable. In the present invention, CaO / SiO_Two(Mol
Ratio) 0.6 to 2.0 cement to Al_TwoO_ThreePercent of
If the cement-based clinker 100% by weight, Al
_TwoO_ThreeIf it is less than 5% by weight, strength in short-term aging cannot be obtained.
Strength under high temperature and high pressure environment
Cannot be maintained. 100% by weight of cement
For Al_TwoO _ThreeIf over 40% by weight
However, the strength development is poor over a long term.

Further, CaO / SiO_Two(Molar ratio) 0.6-
In a cement clinker having a chemical composition of 2.0
For the first time, the initial purpose can be achieved, and CaO / S
iO _TwoIs less than 0.6, and CaO / SiO_TwoIs 2.0
If it exceeds, the strength development is poor, making it difficult to use in practice.
is there. The cement clinker used in the present invention is low
It is discharged from the tally kiln and cooled, but the finishing mill
Thoroughly pour water before milling and / or milling
To produce cement. Sema obtained in this way
Is slower than cement obtained by normal manufacturing methods.
Because of its hardness, it takes time to fill the geothermal well when constructing it.
Suitable for use in such geothermal well cement
You.

[0014] In the method for producing a cement for geothermal wells of the present invention, additives used for ordinary cement can be added. As these additives, a dispersing agent, a setting retarder such as lignin sulfonate, a specific gravity adjusting material such as perlite, and other additives can be added as required. The method for producing the cement for geothermal wells of the present invention is the production method as described above. At this time, the source material of the Al ₂ O ₃ is preferably in the form of powder, and the particle size is usually 200 μm or less. Also, in terms of the Blaine value, it is usually 1500 to 4000 cm ² /
g, preferably 2000 to 3500 cm ² / g.

[0015]

According to the present invention, cementitious clinker is carried out from the rotary kiln, the molar ratio of CaO / SiO ₂ is triturated from well over water to cementitious clinker having the chemical composition of 0.6 to 2.0 As a result, the resulting pulverized product can be obtained as a cement having a delayed effect. Further, a large amount of Al ₂ O ₃ , that is, 5% by weight of Al ₂ O ₃
By containing ４０40% by weight, zonotrite is hardly generated in the hardened cement even under a high temperature and high pressure environment. As a result, it is considered that the decrease in strength due to generation of zonotolite is suppressed.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited to these examples.

[Example] Clinker mineral composition is C ₂ S8
A high belite clinker of 4%, C _{3 A} 2% and C ₄ AF 14% is mixed with silica to form an alumina source.
Add calcium aluminate and blast furnace slag, and change the amount of water sprayed in the mill.
It was pulverized to m ² / g to produce a geothermal well cement. Watering amount in mill, CaO / SiO ₂ molar ratio of test cement,
Table 1 shows the types and amounts of the alumina sources.

In order to evaluate the physical properties after the hydrothermal treatment, first, water was added to the cement, and the specific gravity of the cement slurry was 1.80.
Was adjusted. The cement slurry was poured into a 2-inch cubic brass mold based on the strength test standard of the American Petroleum Institute (API), and subjected to hydrothermal treatment under a saturated vapor pressure of 350 ° C. for a maximum period of 3 months. Table 1 shows the results of the strength test at a prescribed age.

[0019]

[Table 1]

As shown in Table 1, in the comparative example, the setting time is extremely short because of the amount of water sprayed in the mill during normal operation.
The setting time is prolonged, which is convenient for securing workability. On the other hand, the cement of Comparative Example 8 having a small alumina content decreases in strength with age, but by adding an alumina source as in the present invention 4, there is no such decrease in strength and excellent in long-term durability. Is determined to be a cured product.

[0021]

The method for producing the cement for geothermal wells of the present invention.
Is transported out of the rotary kiln and CaO / SiO_Two
Having a chemical composition having a molar ratio of 0.6 to 2.0
Pulverize the system clinker with water and pulverize it.
Al in crushed material_TwoO _ThreeSource material is Al_TwoO_Three5% by weight to 40 weights
By mixing the amount to be%, the conventional geothermal well
The cement production method for geothermal wells is different from the production method for cement.
Excellent long-lasting properties and cures under long-term high-temperature and high-pressure environments
Maintain desired strength without reducing body strength
It has an excellent effect that it can be performed.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 18:14)

Claims (2)

[Claims] 1. The method according to claim 1, wherein the CaO /
A cement clinker having a chemical composition of SiO _{2 having} a molar ratio of 0.6 to 2.0 is pulverized while spraying a large amount of water, and the obtained pulverized material is powdered with an Al ₂ O ₃ source of Al ₂ O ₃ 5
A method for producing a cement for geothermal wells, wherein the cement is mixed in an amount of from 40% by weight to 40% by weight. 2. The CaO / SiO ₂ molar ratio is from 0.6 to ₂ .
Clinker having a chemical composition of 0 and Al ₂ O
_The method for producing a geothermal well cement according to claim 1, wherein pulverization is performed while spraying a large amount of water on the _three source materials.