JPS59128249A - Super low gravity cement and cement slurry for high temperature - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultra-low specific gravity cementing material that has excellent workability and strength development under construction conditions of high temperature and high pressure. More specifically, the present invention relates to ultra-low specific gravity cement and cement slurry for high temperatures that exhibit excellent workability and strength development under high temperature and high pressure construction conditions such as in geothermal wells.

In recent years, in connection with the diversification of energy, new geothermal power generation technology has been developed. Attempts are being made to do so. In this case, in order to prevent the wall of the geothermal well from collapsing, cement is filled between the long steel pipe (casing pipe) and the well wall. The main purpose is to prevent the inflow of cold underground water.

The inside of a geothermal well is under conditions of extremely high temperature and pressure, and this type of cement requires particularly high quality.

That is, in order to evenly fill the construction site with cement slurry, it is required to exhibit excellent fluidity for a predetermined period of time under high temperature and high pressure. On the other hand, geological formations in which high-temperature steam is stored are generally fragile and are prone to collapse of pit walls or leakage of cement slurry into the formation, and in order to prevent this, cement with a low slurry specific gravity is required. Furthermore, after construction, the cement needs to quickly develop sufficient strength to fix the steel pipe (for example, the compressive strength after 24 hours after construction is 35 kgf/
crn' or higher).

Conventionally, this type of cementing material has been made of slurry with a specific gravity of 1.7 to 1, which is based on various types of cement specified by the American Petroleum Institute, with the addition of specific gravity adjusting agents, etc.
3 has been used. However, even with this level of low specific gravity, it is insufficient to prevent collapse of pit walls or leakage of cement slurry, and therefore it is desired to develop ultra-low specific gravity cement with even lower slurry specific gravity. .

If you just want to lower the specific gravity of cement slurry,
It can be easily inferred that this is possible by increasing the ratio of addition of specific gravity adjusting agent to cement. However, simply increasing the addition ratio of the specific gravity adjusting agent causes various problems in terms of physical properties, such as a relatively small proportion of the main components effective for coagulation and hardening of the obtained Shichimen I slurry. Because of this, a practically excellent ultra-low specific gravity cement for high temperatures has not yet been obtained.

That is, the method of adding a large amount of specific gravity adjusting material alone has the problem that the viscosity of the cement slurry increases abnormally, making it difficult to fill the slurry into the place where it is to be applied. Furthermore, after construction, sufficient strength for fixing the steel pipe cannot be quickly developed. Furthermore, when the wellbore temperature is high, it is necessary to increase the amount of setting retarder added, which makes it easier for the specific gravity adjustment material in the slurry to float and separate, resulting in a significant drop in fluidity and uneven hardening. Problems such as becoming

Therefore, the present inventor conducted various studies to solve the above problems, and as a result, the following 7-mention composition was found to be a cementing material used in construction conditions under high temperature and high pressure such as geothermal wells. This was found to be very desirable and led to the present invention.

That is, the present invention provides pace cement, siliceous material,
It consists of a composition containing a bentonite specific gravity adjusting agent, slaked lime, and a blast furnace slab, the pace cement is mainly composed of 2CaO・Si02, and the siliceous material is the total Ca of the composition.
O/SiO2 ratio is 0.5 to 1 on a molar ratio basis,
Bentonite: 2 to 8% based on the internal weight of the composition, and the apparent specific gravity is 0.0.
Specific gravity adjusting material of 7 or less: 10-45%, slaked lime: 1-6%
, and blast furnace slag: Provides an ultra-low specific gravity cement for high temperatures, which is characterized by a content in the range of 5 to 20%.

The cement of the present invention has the following differences in constituent components compared to cements conventionally used for similar purposes (compositions including pace cement, silicic acid material, specific gravity adjusting agent, and bentonite). It also exhibits excellent quality characteristics even under high temperature conditions of about 350°C or more.

(1) The main difference in the components is that of conventional cement (2
The method is to add required amounts of slaked lime and blast furnace slag to a seven-mention composition containing a pace cement whose main component is Cao.Si02.

(2) There is no abnormal increase in the viscosity of cement I slurry generated on-site using conventional cement, and the viscosity changes well over time.

(3) Develop sufficient strength to fix the steel pipe within 24 hours after the start of construction.

(4) Since the specific gravity adjusting material in the cement slurry does not float or move, the setting and hardening are uniform.

The cement of the present invention can not only be used in a high temperature range of about 350°C or more, but also in a high temperature range of about 150°C to 350°C by appropriately selecting the type and amount of setting retarder.
It can be used over a wide temperature range of 50'O. In addition, due to its excellent high-temperature properties, it is used not only for cementing geothermal wells and oil wells, but also for hot spring-related work that requires heat resistance and general civil engineering and construction-related work. I can do something.

The base cement used in the present invention is 2CaO-8i
It contains 80% or more of O2.

Note that the gypsum content in the base cement is preferably about 5% by weight or less (based on SO3), and if it exceeds this, the strength development property will decrease, so it is not preferable.

The above-mentioned base cement is manufactured by adding Talinker alone or with Talinker and the required amount of gypsum, and then crushing the cement so that the Blaine surface area is in the range of about 1800 to 400.0 cm'/g. is preferred.

As a silicic acid substance, for example, the content of 5i02 is 80
% or more of crushed silica stone, silica sand, etc. is preferable. The silicate additive is blended so that the molar ratio of CaO/5i02 in the ultra-low specific gravity cement of the present invention is about 0.5 to 1.0. Outside this range, it is not preferable mainly because the strength development property decreases. Siliceous substances are about 200
It is preferable to use it by pulverizing it to 0 to 5000 cm'/g (Brain surface area).

The specific gravity adjusting material used in the present invention has an apparent specific gravity of approximately 0.7.
(under atmospheric pressure), and those with an apparent specific gravity of less than about 0.0 liters are commonly used. Examples of specific gravity adjusting materials used in the present invention include aluminosilicate I.
Hollow particles made of , porcelain sorter, alumina, carphone, etc. can be mentioned. Specific examples of these include aluminosilicate glass balloons (lightweight fly ash, shirasu balloons, etc.), borosilicate glass balloons, alumina bubbles, and carbon spheres.The main components of these specific gravity adjusting materials are crystals. Either quality or non-crystalline purchases are acceptable.

Further, the specific gravity adjusting material used in the present invention is difficult to break or absorb water under high water pressure, and preferably has a diameter of about 2.5 mm or less. The blending ratio of the specific gravity adjusting agent varies depending on the apparent specific gravity of the specific gravity adjusting agent used and the specific gravity of the intended cement slurry, but it is added in a range of about 10 to 45% based on the internal weight of the cement composition. Note that when the apparent specific gravity of the specific gravity adjusting material exceeds approximately 0.7, the amount required to adjust the specified slurry specific gravity becomes extremely large, leading to flotation separation in the slurry and a decrease in fluidity. Problems such as uneven running force occur.

Bentonite prevents the specific gravity adjusting material from becoming uneven in the slurry. The amount of bentonite to be added is preferably about 2 to 8% (based on the internal weight of the cement composition); if it exceeds this, no improvement in the anti-separation effect is expected, and the strength development property decreases, so it is not preferable. .

Addition of slaked lime can moderate the initial water use reaction of the base cement 71 through interaction with blast furnace slag and improve the flow of cement slurry when the cement is based on 2Ca'O・SiO□. It has the effect of improving sex. The amount of slaked lime is preferably about 1 to 6% by weight,
If more than this amount is added, the setting time (in this field, the
Since the setting time (referred to as the setting time) becomes extremely short, a large amount of setting retarder is required to obtain the specified setting time, which may result in a decrease in strength development or separation of the specific gravity adjusting material from floatation. This is not desirable because it is more likely to occur.

The blast furnace slag used is of the quality normally used for the production of blast furnace cement.
It is ground to ~4500 cm'/g' (Brain surface area) and added at about 5-20% based on the inside weight of the ultra-low specific gravity cement (composition) of the present invention.

Outside this range, problems such as a decrease in the fluidity of the resulting cement slurry, a decrease in strength development, and flotation separation of the specific gravity adjusting material are undesirable.

The ultra-low specific gravity cement of the present invention includes the above-mentioned base cement,
It is obtained by mixing a silicic acid substance, a specific gravity adjusting material, bentonite, slaked lime, and blast furnace slag, but for the combination of other materials other than the specific gravity adjusting material, it is mixed and pulverized and then combined with the specific gravity adjusting material. You may use it.

In addition, when using the cement of the present invention, an appropriate amount of setting retarder is added to the construction conditions, but if these retarders are in powder form, they may be mixed in advance during the production of the ultra-low specific gravity cement of the present invention. You can also.

Examples of the setting agent include lignin sulfonate, cellulose, oxycarboxylate, β-
Those selected from naphthalene sulfone butybase condensate boron compounds and those containing aluminum hydroxide as a main component can be used.

Examples and comparative examples of the present invention are shown below.

[Examples 1 to 2], [Comparative Examples 1 to 6] The amount of siliceous material blended with respect to the base cement was 0.8 based on the CaO/SiO2 molar ratio in the cement I composition.
, specific gravity adjusting material whose main component is aluminosilicate glass balloon (apparent specific gravity = 0°63.5iO256%, A
Ultra-low specific gravity cement compositions were prepared by keeping the blending amounts of 0333%) and bentonite constant at 35% by weight and 4% by weight, respectively, and varying the blending amounts of slaked lime and blast furnace slag. Set retarders (compositions of calcium lignin sulfonate and potassium borate,
weight ratio 2:1), and water (cement mix 10
(52 parts by weight to 0 parts by weight) to prepare a slurry with a specific gravity of 1.2, and a setting test (fluidity and setting time) assuming cementing at a well temperature of 350 ° C.
and compressive strength tests were conducted. Table 1 shows the composition of the ultra-low specific gravity cement mixture used in the test, and Table 2 shows the test results.

The base cement and test method used are as follows.

(1) Composition of base cement (to) φ) 3CaO*S
iO23 2CaO@ 5i02 923
Cao ・Al'z 030 4CaO*AJ1203*Fe2O34So3
0. '1 (2) Weight% of CaO and 5i02 in the blended componentsCaO5i02 Base cement 64.0 32.8 Silicic acid material 0.0 95.4 Aluminosilicate glass balloon 0.5 58.0 Bentonite l--2, 562.7 Blast furnace slag 41.4 33.1 Slaked lime
74.2 0.0(3) Setting test for ultra-low specific gravity cement composition slurry, wellbore temperature 3
The temperature and pressure were raised under conditions simulating cementing at 50'C, and the setting time and fluidity were tested.

The setting test was performed using a thickening time tester specified by the American Petroleum Institute (API), and the time required from the start of increasing the temperature and pressure of the cement composition slurry until the viscosity of the slurry reached 100 poise (hereinafter referred to as setting time) ).

In addition, fluidity was determined from the shape of the change in slurry viscosity over time during this period. A typical pattern of the change in viscosity of a cement composition slurry over time is approximately as shown in FIG. Among these, as shown in (a), the viscosity remains low at the beginning, and after about 3 to 5 hours, the viscosity rises rapidly.
00 poise is preferable, and in the following, those exhibiting a viscosity change similar to this were judged to have "good" fluidity. On the other hand, as shown in (b) and (/\), the slurry viscosity becomes 30 poise or more within 3 hours,
This is undesirable because it becomes difficult to feed the cement slurry into the well during actual construction, and below, those exhibiting viscosity changes similar to these were determined to have "poor" fluidity.

(4) Compressive strength test The cement composition slurry was cured at high temperature and pressure for 24 hours in a curing chamber specified by the American Petroleum Institute, and the compressive strength of the hardened product was tested.

Table 1 Composition of cement composition (wt%) basis Silicic acid Slaked lime Blast furnace Set cementitious substance Slag Retarder Example 1 41 4 1 15 22 4
4 7 5 5 2 Comparative example 1'547 0 05 2 53 6 0 2 23 4
6 5 0 10 24 49 8
4 0 35 449 8 0
2 6 26 0 0 35 2 Note) The blending amounts of aluminosilicate balloon and Ben I/Nite were constant at 35% by weight and 4% by weight, respectively.

These weight percentages and the weight percentages of each component (excluding the setting retarder) in Table 1 refer to the amounts blended in the cement composition (prior to the addition of the setting retarder) (the same applies hereinafter). In addition, the weight percent of the setting retarder is 10% by weight of the cement I composition.
The blending amount is shown when it is 0% by weight.

Table 2 Test results Fluidity Setting time Compressive strength (kgf/am') Example I Good 221
662 good 192
59 Comparative Example 1 Defective 265 512 Defective 259 523 Defective
272 544 Defective 243
425 Good 101
286 good 2
32 25F Examples 3 to 5, [Comparative Examples 7 to 8] Based on the base cement (same composition as that used in Example 1), 0 to 24% by weight of siliceous material, 4 to 4% of slaked lime 6% by weight, and a specific gravity adjusting material whose main components are aluminosilicate I and glass balloons (apparent specific gravity: 0.63)
), the blending amounts of bentonite and blast furnace slag are fixed at 35% by weight, 4% by weight, and 15% by weight, respectively, and the CaO/SiO□ molar ratio in the cement composition is 0.4~
An ultra-low specific gravity cement I composition of 1.1 was prepared. However, the specific gravity adjusting material mainly composed of aluminosilicate glass balloons used in Comparative Example 8 contained 0.4% by weight of CaO.
, 5in252.8% by weight and the remainder is mainly A n 2
03, and the specific gravity adjusting material mainly composed of aluminosilicate glass balloons used in other examples was Ca
O0.5% by weight, 5iO2 58.0% by weight, the remainder being mainly AsL203.

A setting retarder (composition of calcium lignia sulfonate and potassium borate, weight ratio 2) is added to these seven-mention compositions.
:1) 2% by weight (proportion to cement composition) and water (52 parts by weight relative to 100 parts by weight of cement mixture)
was added to prepare a slurry with a specific gravity of 1°2, and heated at 350°C.
A compressive strength test after curing for 124 hours was conducted by the method described in Example 1. Table 3 shows the compositions and test results of the ultra-low specific gravity cement formulations used in the tests.

Table 3 Composition of cement composition (wt%) and compression test (24 hours) results basis Silicic acid Slaked stone CaO/5i02 Compressive strength Cementitious material Ash Molar ratio (kgf/cm') Example 3 24 18 4 0 .5 48437
5 4 0.8 62540 0 6
1.0 42 Comparative Example 7 18 24 4 0.4 29842
0 4 1.1 26th edition) Aluminosilicate/Helune: 35% by weight Bentonite = 4% by weight Blast furnace slag: 15% by weight [Examples 6-7, [Comparative Example 9] Base cement (used in Example 1) (with the same composition as), 0 to 18% by weight of a silicic acid substance, slaked lime, and a specific gravity adjusting material whose main components are aluminosilicate glass balloons (apparent specific gravity: 0.63, in Example 3). (with the same composition as that used), the blended amounts of bentonite and blast furnace slag were 4% by weight, 42% by weight, and 4% by weight, respectively.
The wt% and 15wt% are constant, and the CaO/SiO2 molar ratio in the cement composition is 0, 4~0, 8 (7
) An ultra-low specific gravity cement composition was prepared.

A set retarder (composition of calcium lignin sulfonate and potassium borate, weight ratio 2) is added to these cement compositions.
:1) 2% by weight (proportion to cement composition) and water (52 parts by weight relative to 100 parts by weight of cement mixture)
was added to prepare a slurry with a specific gravity of 1°1, and heated at 350°C.
A compressive strength test after curing for 124 hours was carried out according to Method No. 5 described in Example II. Table 4 shows the composition and test results of the ultra-low specific gravity cement mixture used in the test.

Table 4 Composition of cement composition (wt%) and compression test (24 hours) results basis Keiship CaO/5iC1z JIf
71-Molar substance molar ratio (k
gf/cml') Example 6 23 12 0.5 467 35
0 0.8 52 Comparative Example 9 17 18 0,. 4 25 Note) Aluminosilicate/Helune = 42% by weight bentonite:
4% by weight Blast furnace slag; 15% by weight [Examples 8 to 10], [Comparative Example 10] In the above-mentioned Example 4, alumina 7 hepul, carbon spheres or borosilicate was used instead of aluminosilicate glass as the specific gravity adjusting material. using glass balloons,
The same procedure as in Example 4 was carried out except that the blending amounts of the base cement and siliceous material were changed to the proportions shown in Table 5 in order to make the molar ratio of CaO/S 'r 02 in the cement composition 0.8. A cement composition slurry was prepared.

Next, this cement composition slurry was subjected to a setting test (fluidity and setting time) and a compressive strength test assuming cementing at a well temperature of 350° C. in the same manner as in Example 1. Table 5 shows the composition of the ultra-low specific gravity cement formulations tested, and Table 6 shows the test results.

Table 5 Composition (% by weight) of the 7-mention composition Base Silicic acid Specific gravity adjusting material Material (apparent specific gravity) Example 8 25 19 Alumina bubble (0,60)
33 9 38 27 Carphone Sphere (0, 15
) 12 10 48 11 Borosilicate crow balloon (
0,32) is Comparative Example 10 16 13 Alumina bubble (0,84
) 48th edition) Slaked lime 24% by weight Bentonite blast furnace slag: 15% by weight Table 6 Test results Fluidity Setting time Compressive strength (kgf/cm') Example 8 Good 205
689 good 223
721 0 good
2 18 63 Comparative Example 10 Defective 188 5 [Examples 11 to 12] In Example 1 described above, the amount of setting retarder added to the ultra-low specific gravity composition prepared was 0.

A similar cement composition slurry was obtained except that the content was changed to 3% by weight, and a setting test (fluidity and setting time) and a compressive strength test were performed on this slurry assuming cementing under well-like conditions at 250'c. I did the same thing---[
Example 11].

A similar cement composition slurry was obtained in Example 1, except that the amount of the setting retarder added to the prepared ultra-low specific gravity cement composition was changed to 3.5% by weight. A setting test (fluidity and setting time) and a compressive strength test assuming cementing at 400°C under well-like conditions were conducted in the same manner for [Example 12]
].

The test results are shown in Table 7.

Table 7 Test results JAt dynamics Set time Compressive strength
(kgf/cm') Example 1 1 Good 2 2 1
5 31 2 Good 2
01 68

[Brief explanation of drawings]

FIG. 1 shows an example of a pattern of change in cement composition slurry viscosity over time. (A): Example of a preferred pattern for a cement composition for wells. (g), (c): Examples of unfavorable patterns of well overment compositions. Patent applicant Yasuo Yanagawa, agent for Ube Industries, Ltd., patent attorney

Claims (1)

[Claims] ■. It consists of a base cement, a siliceous material, bentonite, a specific gravity adjusting material with an apparent specific gravity of 0.7 or less, slaked lime, and blast furnace slag, and the pace cement is 2C
ao.5i02 as a main component, the siliceous material is blended so that the total CaO/5i02 ratio of the composition is 0.5 to 1.0 on a molar ratio basis, and , the amount of other main constituents is based on the internal weight of the composition, bentonite: 2 to 8%, and the apparent specific gravity is 0.
Specific gravity adjusting material of 7 or less: 10-45%, slaked lime: 1-6%
, and blast furnace slag: an ultra-low specific gravity cement for high temperatures, characterized in that it is in the range of 5 to 20%. It consists of a composition containing 2° base cement, silicic acid material, bentonite, a specific gravity adjusting material with an apparent specific gravity of 0.7 or less, slaked lime, and blast furnace slag.
The siliceous material is mainly composed of aO.SiO3, and the siliceous material is blended so that the total CaO/5i02 ratio of the composition is 0.5 to 1.0 on a molar ratio basis, and , the amount of other main components is based on the internal weight of the composition, benite = 2 to 8%, and the apparent specific gravity is 0.
．． Specific gravity adjusting material below 7: 10-45%, slaked lime: 1-6
%, and blast furnace slag: an ultra-low specific gravity cement slurry for high temperatures with a specific gravity of 1.3 or less, which is obtained by dispersing a cement composition in the range of 5 to 20% in water.