JPS6050740B2 - Cement composition and its construction method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a cement composition and a method for applying the same.

Bortland cement is conventionally manufactured by grinding limestone, clay and/or other materials into a fine powder, thoroughly mixing them, and then firing the mixture in a long rotating kiln. . In the heating zone of the kiln, at a temperature close to 1671° C., the mixture is sintered and melted into a mass called clinker, which is ground into a fine powder.

However, to make low-cost, high-capacity Boltland cement, a large amount of fuel is required, and as with all energy-consuming industries, the fuel itself is starting to become scarce, so the methods described above are used to make Boltland cement. It is becoming difficult to create. Therefore, there is a need for the emergence of cements with low energy consumption. As fuels such as coal are becoming scarce, high-energy fuels are needed.
Attempts are being made to recover and liberate geothermal energy and oil and gas from very deep rifts.

Furthermore, devices using nuclear fission have been proposed as a method of obtaining energy in high yield. However, the inherent high temperatures underground and the heat added by the core can be combined to strengthen the walls and pipes of the well, or to connect the above-ground pipes and valve assemblies by attaching the pipes to the walls in the desired arrangement. Then,
A serious defect arises in that the stability of the cement deteriorates. The high temperature gradients that define the thermal profile of these wells create various sources of stress between the cement and the steel pipes.
The coefficient of thermal expansion of metal is 5 to 50 to 1, which is higher than that of cement, so if the bonding strength of cement is insufficient,
Adhesion deteriorates. Ordinary Boltland cement is 1
It does not rapidly lose its adhesive strength at temperatures of 49° C. and above, and only has a marginal strength at optimal temperature conditions. For example, the shear force between boltland cement and a rod of conventional steel reinforcement averages 500 psi, while the shear force between boltland cement and conventional fabricated steel is only 50 pSi. When stressed due to thermal degradation, Boltland cement becomes useless for securing vibrators in wells such as those described above. There is therefore a need for a high strength cement that has the requisite degree of adhesion and high shear for use in the above applications. When drilling conventional oil and gas wells, the vibrator is cemented to secure the vibrator within the well and to prevent water from coming into contact with the oil and gas generating zone within the well.

A typical method of cementing a well as described above is to mix the Boltland cement composition in place in the well, pump the cement downward through a vibrator, and then pump the cement between the well and the vibrator. It consists of pumping outward and upward. Typically, multiple high-pressure pumps and vibrator systems are required to avoid destroying the pumps. When a pump fails, the cement solidifies and hardens virtually immediately, rendering the well unusable and requiring expensive drilling operations. As described above, there is a cement construction method that allows the vibrator to be fixed in a well while maintaining the cement so that it does not harden except by the passage of time, by subjecting the cement to a predetermined temperature condition in the well, or both. Appearance is requested. Improved cement compositions and methods of application are disclosed in U.S. Pat.
、． 011,2,238,930,2,279,262
,2,302,913,2,502,418,2,58
6,814,2,665,996,2,682,092
,2,701,209,2,805,719,2,88
3,723,2,895,838,3,146,828
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JetPerf0ratjng0nB0ndStren
gth0fCement. J, and particularly detailed descriptions are given in U.S. Pat.
996,3,146,828, 3,326,269 and 3,736,163.

US Pat. No. 1,852,672 describes a silica cement consisting of an activated clay material and an alkaline earth oxide such as calcium oxyfluoride or magnesium oxide. Also,
US Pat. No. 3,326,269 describes a method of fixing free silica by calcining mixtures of colloidal silica and various colloidal polyvalent metal hydroxides at high temperatures.
Further, U.S. Pat. No. 3,146,828 describes a method for producing a tough mineral material consisting of ordinary low strength silica and highly porous silicate, of at most 1546 pSi, using heat. has been done.

This patent teaches the use of a material that forms a rigid boundary of permeable structures within a well construction, the purpose of which is to aid in the disruption of the construction and to continuously recover fluids. It is to be. The binding or cementing material is sodium silicate, with the addition of 0.5 to 2.0 parts by weight of zinc oxide as a stabilizer to reduce sensitivity to water. This patent states that the use of large amounts of zinc oxide is undesirable, and the sodium silicate solution is thermally dehydrated at such a rate that a porous film is formed which acts as a binder. The reaction rate is shown at a minimum temperature of 80°C. U.S. Patent 3,146,
828 cement is a water vapor sensitive product that is stable under low humidity conditions, but has been found to soften and degrade within 2 hours at 80°C at 100% relative humidity. A formulation as described in column 5, digits 1-6 of this patent was prepared and was heated at 100% relative humidity at 79.4°C.
Curing in a closed autoclave for 5 days results in a product that is not plastic and tough unless the sample is dehydrated.
Once evaporated, the cement hardens. When such a formulation is placed in a well, water vapor migrates from the cement and
Hardening occurs. If the formulation is hard or the cement is placed in a non-perforated steel tube, the cement will not harden;
The requisite porosity of the invention of US Pat. No. 3,146,828 is not achieved. Thus, U.S. Patent 3,146,828
The formulations described in , however, have drawbacks. US patent 2
, 665,996 describes a hydrated calcium silicate crystalline product that is unstable at temperatures above 232.0° C. and reactive at both room and elevated temperatures.

Furthermore, the cement described in this patent does not have adhesive properties to steel. U.S. Patent 3,736,163 states:
A lightweight, heat-resistant product is described that combines calcium silicate and mineral wool-type fibers, which partially mineralizes during use.

Curing the product described in this patent in an autoclave at 204°C and 200 pSj steam for 3 hours, followed by drying, results in a product that has negligible adhesion to metal, and the main components of the product is a crystalline hydrate of dicalcium silicate that is only partially dehydrated at the beginning of use. The product described in U.S. Pat. No. 3,736,163 withstands temperatures below 6490C because small fractures and distortions are eliminated by the fibrous filler, making it unstressed. 720 gallons of water, 8 gallons of lime
75 bond, uncalcined diatomaceous earth 750 bond, anhydrous sodium silicate 150 bond, sand 7 bond, nodular mineral wool 60 bond, sulfite bulb fiber 60 bond, clay 50 bond in an autoclave. It was then determined by X-ray analysis that a product consisting of a mixture of crystalline calcium silicate was obtained.
The composition of this patent contains a large amount of water. As mentioned above, the conventional technology has advantages and disadvantages, but it can maintain mobility or pumpability for a long period of time at temperatures below the activation temperature, and it hardens under predetermined conditions to fix the vibrator in the well. Cement compositions with good physical, mechanical, and chemical properties can be obtained without the need for redundant pumping or circulation equipment, and with the use of minimal amounts of water. Therefore, it has been desired to develop a cement composition that satisfies all of the above requirements. The present invention has been made in view of the above circumstances, and its object is to provide a hydrothermal solution consisting of a mixture that remains movable or pumpable for a long period of time at temperatures below the activation temperature at which curing begins. (HydrOthe
To provide a cement composition having a characteristic of setting that starts (rmally).

Another object of the present invention is to provide a cement composition comprising a high molecular weight inorganic polymer obtained by reacting a polyvalent metal and silica under conditions of predetermined moisture and high temperature.

Another object of the present invention is to provide a hydrothermal cement composition comprising a mixture of a polyvalent metal salt, water and a source of silica which can combine with the polyvalent metal salt upon application of heat and hydrate under predetermined conditions of temperature and time. It's about providing things.

Another object of the invention is to supply said cement composition into a well into which a series of vibrators are inserted, and then to cure said cement composition by the heat of the well, thereby fixing said vibrators within the well. The purpose of this project is to provide a cement construction method.

Another object of the invention is to provide a method that does not require redundant pumping or circulation equipment, since the destruction of the equipment does not result in hardening of the cement in the well.

Still another object of the present invention is to provide a method that allows cement to be mixed off-site and transported to the site, while allowing it to be kept hardened and hardened before use for a longer period of time than Boltland cement. There is a particular thing.

Another object of the invention is a cement composition containing reagents that minimize the amount of water required to obtain the workability of a slurry containing cement-forming reactants, the composition comprising: The object of the present invention is to provide a cement composition with optimal chemical properties.

Still other objects of the invention include high mechanical strength, chemical resistance,
The object is to provide coatings, binders or construction products that are abrasion resistant, resistant to long-term ignition, and resistant to thermal cycling.

Still another object of the present invention is to provide a vibrator to a well well without the need for cementing equipment fitted with a pair of pumps and associated equipment, and without creating a risk of hardening of the cement before the desired time. An object of the present invention is to provide a cement composition that can be fixed and fixed in the interior of the interior of the earth, and a method for applying the same.

The present invention provides a cement composition that hardens by a hydrothermally initiated reaction, that is, that hardens hydrothermally, comprising a cement mixture that maintains mobility and pumpability at temperatures below the activation temperature at which hardening begins. Regarding.

Additionally, the present invention provides high strength cement compositions that can be cured over normal time or by exposure to high temperatures, or both, and are particularly suitable for creating underground wells that are stable and hot when cured, and that require less energy. The present invention relates to a cement composition that can minimize the amount of water and fuel used, as well as a cement construction method for fixing a vibrator in a well using the above-mentioned hydrothermal cement composition. The present invention will be explained in more detail below.

The cement composition of the present invention includes (a) about 5 to 15 parts by weight of at least one low-solubility compound selected from the group consisting of zinc oxide, aluminum oxide, and aluminum hydroxide, and (b) the above ( a
(c) about 60 to 10 parts of at least one silica source from the group consisting of silica fine powder, silica sand, which is chemically bonded to the component and hydrated under specified conditions;
about 5 to 15 parts by weight of spray-dried sodium silicate hydrate or sodium hydroxide as a water reducing agent and (d
) A cement composition comprising about 15 to 10 parts by weight of water per 100 parts by weight of the above components (a), (b), and (c).

The reactants of the polyvalent metal ion source, which is component (a) of the cement composition of the present invention, are polyvalent metal oxides, their hydroxides, salts with low solubility, and mixtures thereof.

Usable polyvalent metal oxides, hydroxides, and salts thereof include, for example, zinc oxide, magnesium oxide, iron oxide, aluminum oxide, manganese oxide, titanium oxide, zirconium oxide,
Vanadium oxide, hafnium oxide, aluminum hydroxide, zinc carbonate, magnesium carbonate, calcium phosphate, magnesium phosphate, aluminum phosphate or mixtures thereof. In addition, the silica source of component (b) used in the present invention is clay, fine silica powder, silica sand, or a mixture thereof.

Furthermore, the water amount reducing agent (C) component used in the present invention is
For example, spray dried sodium silicate hydrate powder. It is also possible to use sodium hydroxide as a precursor of sodium silicate. Water is added to harden the cement. Next, the blending amounts of various components used in the composition of the present invention will be explained.

The amount of polyvalent metal ion source is about 50-15 parts by weight, preferably 7 parts by weight.

Further, the amount of the silica source that can chemically bond with component (a) of the polyvalent metal ion source when heat is applied and be hydrated under predetermined temperature and time conditions is about 60 to 10 parts by volume, preferably The silica source consisted of about 5 parts by weight of sand, about 25 parts by weight of fine silica powder, and about 1 part by weight of anhydrous sodium silicate powder. The silica source may also consist of about 40 to 6 parts sand and about 20 to 4 parts fine silica powder. Furthermore, fly ash approx.
It can also contain 5 parts by weight or less. Also, the amount of water reducing agent, such as spray-dried hydrated sodium silicate powder, is about 5 to 15 parts by weight, preferably about 1 part by weight. In addition, sodium hydroxide as a sodium silicate precursor/body is about 1
~1 part by weight, preferably about 5 parts by weight, may also be used. Further, the amount of water is about 15 to 2 parts by weight, preferably about 1 part by weight, per 1 (4) parts by weight of components (a), (b), and (c). Next, a method for preparing the cement composition of the present invention will be explained.

The cement composition of the present invention comprises a polyvalent metal ion source of low solubility polyvalent metal salts, their oxides, hydroxides or mixtures thereof, a silica source of clay, silica fine powder, silica sand, sodium silicate or It is prepared by dry compounding their equivalents.

A water reducing agent consisting of spray dried hydrated sodium silicate powder is used to reduce the amount of water required to fluidize the system. Preferably, the compounding or mixing step is carried out in a closed container free of air and water to prevent caking due to moisture and to prevent carbonation of the silicate by carbon dioxide in the air. The dry material formulation is then slurried with the minimum amount of water necessary. If the water is added too late, the powdered mixture will cake, especially under wet conditions, and will be difficult to disperse and hydrate. The consistency of the water and solids mixture changes significantly within one drop after the addition of water, and the clay is rapidly reduced, turning the wet cake into a thin pumpable slurry. This occurs due to the dissolution of hydrated sodium silicate. The viscosity of the slurry changes rapidly when relatively small amounts of water, on the order of 1-2% by weight, are added. To form polyvalent silicates by reaction of silica with metal oxides, their hydroxides or their salts,
Heat and moisture are required to promote chemical bonding with acidic components.

When heat is applied to polyvalent metal oxides, their hydroxides, their salts, silica fine powder, and alkali metal silicate in an aqueous slurry, polyvalent metal oxidation occurs. compounds, hydroxides or salts are combined with silica gel to form the respective silicates. The silica powder or alkali metal silicate acts as a reagent that reacts with metal oxides to form silicates and alkali metal oxides or hydroxides. The alkaline product reacts with the silica of the sand, silica fine powder, and the product generates reactive sodium silicate. The above cycle is continued until the polyvalent metal is exhausted, the water is evaporated, or all the silica is exhausted or no longer available.
Note that the hydrothermal cement (HydrO
Municipal Ermalcement) refers to the formation of polyvalent silicates by the reaction of low-solubility metal oxides, their hydroxides, and their salts with silica. A cement that has a high degree of mechanical strength under the following conditions.

In addition, the terms "initiation temperature" and "activation temperature" as used herein refer to the lowest temperature at which the above-mentioned reaction begins, and mean a temperature below the temperature at which the above-mentioned substances are a physical mixture. The starting temperature of the hydrothermal cement of the present invention is determined by the type of polyvalent metal ions and the SlO in the sodium silicate used.
It is advantageous to vary according to the ratio 2/Na2O.
Therefore, the cement of the present invention will not harden over a normal period of time unless it is exposed to a sufficiently high temperature for an activation reaction to occur. Since the cement composition of the present invention has the above-mentioned characteristics, it is suitable for being cast into a well.

The cement compositions of the present invention have high strength and are well suited for many other uses. As described above,
Although the cement composition of the present invention can be used in many applications, the case where the cement is used to fix a vibrator in a well will be described below.

A cement composition having the composition as described above is supplied into a well into which a series of vibrators are inserted, and then the cement composition is hardened by the heat of the well, and the vibrators are fixed in the well. construction. The compositions of the invention are hydrothermally reacted products that are inert and unreactive at room temperature, reactive at elevated temperatures, and long-term mobile and pumpable at temperatures below the activation temperature. be.

Furthermore, the product of the present invention cures into a heat-resistant solid;
Adhesive strength to steel is high, acid resistant, amorphous,
It is a polymeric, non-crystalline and anhydrous solid. The compositions of the present invention have minimal amounts of water and are quite different from, for example, the compositions of US Pat. No. 3,736,16. When only a minimal amount of water is present, as in the product of the present invention, a reaction occurs to form a non-crystalline, anhydrous solid polymer, resulting in a product that is resistant to high temperatures and therefore stress free. Fibers, etc., which were necessary to eliminate the problem, are no longer needed. Examples of formulations using various sources of polyvalent metal ions are as follows. Except where otherwise indicated herein, the particle size is smaller than the mesh determined by standard ASTM EH analysis. Example 1 Part by weight Optimal amount
Usable range sand (20~6
0 mesh) 40-6050 silica powder (
325 mesh) 20~4025S102/N
Spray-dried hydrated sodium silicate powder with a2O of 2.4/1 (325 mesh) 5-15
10 parts by weight Optimal amount Usable range Sodium silicate anhydride powder (325 mesh) with SlO2/Na2O ratio of 3.22/1
5~1510 fly ash O~2
50 Zinc oxide (1 micron or less) 5-157 Water
15-20)l(17)l(*
The amount of water is the amount per 100 parts by weight of solids.

The same applies to the following examples. Using the preferred formulation, the cement begins to activate at an activation temperature of 66° C. and hardens at this temperature in 24 hours.

At 93°F, significant hardening is achieved in less than 24 hours.

In about one week, the cement has a compressive strength of 400 pS1 and a shear strength of 1300 pS1 at 93°C. Hardened cement can withstand temperatures up to 1093°C without adversely affecting its physical strength. Similar to the examples described later, in this example as well, the compressive strength was measured using ASTMC.
The pre-shear force or adhesive strength is determined by the measuring methods customary in the petroleum industry. It consists of measuring the force per unit area required to displace or break up the bond between a metal column and a concrete column. Example 2 Part by weight Optimal amount
Usable range sand
40-6050 silica powder
20~4025S102/Na2O is 2
．． 4/1 spray dried hydrated sodium silicate powder
5-1510 Sodium silicate powder SjO
Anhydrous sodium silicate powder with 2/Na2O of 3.22/1 5-1510 Aluminum hydroxide (NaAl2
+Reagent grade produced from NFI4OH) 5
~207 Wed 15-20
1 (17 Water) This formulation is stable at any temperature below 63°C, but begins to thicken rapidly at 93°C.

Although actual curing is not observed below 74°C, the preferred activation temperature at which the curing properties change at an observable rate is 93°C. After curing for 2 weeks at 93°C,
It has a compressive strength of 2000PS1 or more.

Compressive strengths of greater than 3000 pSi are obtained after 4 weeks at 93°C.

A compressive strength of 4000PS1 can be obtained in 5 to 6 weeks at the same temperature. At 149°C, a strength of about 470 pSj can be obtained in two weeks.

This cement has a shear strength of 1300 pSi and withstands temperatures up to 538° C. without adversely affecting its physical strength. Example 3 Part by weight Optimal amount
Usable range sand
40-6050 silica powder
20-40255 Anhydrous sodium silicate powder with S102/Na2O of 3.22/1
2-1510S102/Na2O is 2.4
/1 spray-dried hydrated sodium silicate powder
5-1510 Sodium silicate powder aluminum hydroxide 4 (commercial grade from NaAl2O3 + water vapor)
5-157 Wed
At an activation temperature of the order of 15-20) l (17*107°C, a cement with a strength of 3700 pSi is obtained in about n hours.

Example 4 Part by weight Optimal amount
Usable range sand
40-6050 silica powder
20-4025S102/Na2O is 3.2
2/1 anhydrous sodium silicate powder
5-1510 Spray-dried hydrated sodium silicate powder with S102/Na2O of 2.4/1
5-1510 Sodium Silicate Powder Uncalcined or Rehydrated AI2O35-157 Water
15-20*17* 107°C was the lowest observable actual activation temperature for this formulation.

14 because curing is substantially completed in less than two weeks.
A temperature of 9°C is preferred.

The intensity of 3700 pS1 is approximately 7 at an activation temperature of 149°C.
You can get it in full time.

Example 5 Parts by weight Optimal amount
Usable range sand
40-6050 silica powder
20-4025S102/Na2O is 7.5
/1 anhydrous sodium silicate powder
5-1510 Spray-dried hydrated sodium silicate powder with S102/Na2O of 2.4/1
5-1510 Zinc oxide 5-15
7 Water 15~20* 7*SlO
2/Na2O ratio of 7 instead of 3.22/1.
．． When using 5/1 sodium silicate, the activation temperature is 66
The temperature drops from °C to 38 °C.

The compressive strength of the composition is 3600 pS after 7 days at 38°C.
It becomes 1. When more alkaline sodium silicates are used (ratios of 3/1 and below, ie only 2/1 or 2.4/1), they do not cure even after 5 days at 66°C. The SlO2/Na2O2.4/1 silicate acts as a fluidizing agent or viscosity-enhancing additive during the cement mixing operation. More alkaline silicates require higher temperatures and/or longer times to react and cure. Example 6 The formulations of Examples 1-5 are used.

1 to 1 part by weight of sodium hydroxide is used in place of the anhydrous or hydrated sodium silicate. Preferably, 5 parts by weight of sodium hydroxide are used.

Although such substitutions do not significantly change the chemical and physical properties shown in each example, the reactivity of each formulation changes to some extent. As previously mentioned, other polyvalent metal oxides, hydroxides or salts may also be used in the cement compositions of the present invention.

For example, magnesium oxide, iron oxide, aluminum oxide,
Manganese oxide, titanium oxide, zirconium oxide, vanadium oxide, hafnium oxide, zinc or magnesium carbonate, magnesium phosphate or aluminum phosphate can be used. When the polyvalent metal compounds shown in Examples 1 to 6 are replaced by these, the concentrations are proportional to the relative equivalents (weight) comparable to the equivalents (weight) of the polyvalent metal compounds described in the examples. Although it is not essential to include sodium silicate in these formulations, it is preferred.

Sodium silicate is produced by a highly energy-intensive process. In order to minimize the content of raw materials of this nature, silicates can then be produced in this cement system by reaction of sodium hydroxide with available silica. Various clays, sands and ground sands are suitable sources of silica for this purpose. Washing sands conventionally used in Bortland cement, concrete and mortar can also be used in the cement formulations of the present invention.

This sand has little effect on the strength of the cement, but it does affect the price, flowability and bulking coefficient of the cement mixture. The silica powder should have a low clay content, and the proportion used will determine the flowability and strength of the cured material over time. That is, the use of more silica fines results in a cement mixture that is less fluid before hardening, but produces greater strength after hardening over a given period of time. Regarding the care salts used, it is convenient to use some anhydrous silicates so that no free water is formed after all reactions have finished.

The use of more silicates of this nature results in faster curing. The SiO2/Na2O ratio of sodium silicate is a factor that controls the reaction rate. When the silica grade is high (high SiO2 ratio), it reacts more quickly and at a lower temperature than when the alkali grade is high. Hydrated alkali metal silicate powders, preferably produced by conventional spray drying of alkali metal silicate solutions with SiO2/Na2O ratios in a narrow range, surprisingly exhibit high fluidity with only a small amount of water. It has been found that a slurry of This feature provides unique physical, chemical and mechanical properties. The amount of water required for chemical curing of most inorganic cement systems determines the properties of the final product. Excess or residual water in the cured product may evaporate and escape from weak spots or pores, causing damage, contamination, and reduced strength. All hydraulic cements, such as Boltland cement, contain hydration water or trapped water, but these waters impair the heat resistance of the product. Since only 15-20% water is used in the new cement of the present invention, a cement is obtained which has a higher degree of permeability and a higher degree of mechanical strength than would otherwise be the case.
Addition of water creates a partial solution of hydrated alkali metal silicate powder, which as it dissolves creates a partial charge in the slurry, releasing colloidal electrolyte;
The system fluidizes, providing a high degree of lubricity, and the electrolyte-free slurry becomes a slightly wet powder. Liquefaction does not occur immediately after adding water and blending with the dry powder. After about two minutes with little or no agitation, the wet mass suddenly becomes liquid and highly fluid, allowing it to be easily poured, pumped, and extruded. Then, by adding a suitable bentonite product to this slurry,
This slurry can be made thixotropic. As the water used in the cement composition of the present invention, clear water commonly used in concrete and mortar can be used.

The amount of water affects the flowability and strength of the final product; the more water you use, the more fluid the curing agent mixture will be;
The strength after curing decreases. Water is an essential component that promotes the reaction between silicates and polyvalent metal salts. The concentration of polyvalent metal compounds used in the present invention should be proportional to the equivalent weights of all other ingredients.

If sufficient polyvalent metal compounds are not present, all other components become relatively inactive. Fly ash or other volcanic ash materials can be used as fillers to act similar to sand.

Concrete is produced by adding gravel or rock to the mortar formulation of the invention. Concrete produced in this way exhibits extremely low water absorption even after exposure to temperatures of several hundred degrees during curing. The cement compositions of the invention are therefore particularly suitable for use in the production of buildings; they are produced with low energy and do not require sintering or kilning to produce the raw material for concrete. be able to. Particularly good cement compositions are obtained when sodium silicate is generated by reaction of sodium hydroxide with silica.

As is evident from the above examples, using different polyvalent metal compounds to formulate the cement compositions of the present invention
Different formulations with different activation temperatures result.

For example, the formulation of Example 1 has an activation temperature of 66°C, while the formulation of Example 3 has an activation temperature of 52'C. A formulation with a particular activation temperature is used under a temperature environment specifically suited to that activation temperature to keep the cement mobile until it is subjected to a temperature sufficient to activate the setting reaction. The various cement formulations of the present invention can be used to cement a vibrator or iron pipe in a well dug into the ground. Because the temperature at a given point within a well varies with the depth of the well, the cement composition used to construct the vibe measures the temperature of the well and determines the activity of the various formulations of the present invention. temperature is selected by comparing the temperature of the well with the temperature of the well. For example, if the underground hole temperature is approximately 66°C, the formulation of Example 1 with an activation temperature of 66°C may be used to cure the cement when it is finally placed in the well. be able to. but,
Below these temperatures, unlike conventional Boltland cement, the cement of the present invention remains mobile or pumpable for long periods of time. For use in wells with a variety of different temperatures, a cement formulation should be used that has an activation temperature that corresponds to the temperature of the well. When using the cement formulation of the present invention to install a vibe in a well, the cement is prepared in the manner described above.

Although the cement can be prepared at the well site, it is convenient to prepare it away from the well site and transport it to the site without curing. When holding the cement before use, some agitation is necessary to prevent layering of the material. Considering the transport and mixing problems that occur with conventional Boltland cement, the above-mentioned characteristics of the formulations of the present invention are of great importance. After the cement composition of the present invention has been prepared, it is pumped in a conventional manner into the space between the well wall and the series of vibrators. However, a retaining device for the pump is not absolutely necessary. This is because the cement of the present invention does not harden for several hours when subjected to activation temperatures, allowing sufficient time to repair or replace the pumping equipment. Once in the well, the pump is stopped and the cement is allowed to harden by passing through the well temperature period or both. Using a cement composition having an activation temperature substantially lower than the temperature of the well, hardening will occur in less time than described in the examples. The final strength obtained with the cement of the invention is at least as high as that obtained with conventional Boltland cement, and the shear strength is higher than that of Boltland cement as shown in the Examples. Therefore, the bond strength of the cement formulations of the present invention is much higher than that of conventional Boltland cement, making the formulations of the present invention particularly suitable for use in high temperature wells, such as geothermal wells. The formulations of this invention can be used in a variety of applications depending on the time and temperature required to cure. Although the invention has been described by way of specific examples, it will be obvious that various changes and modifications may be made thereto without departing from the spirit and scope of the invention.

Claims (1)

[Claims] 1 (a) about 5 to 15 parts by weight of at least one low-solubility compound selected from the group consisting of zinc oxide, aluminum oxide, and aluminum hydroxide; (b) the above (
a) about 60 to 100 parts by weight of at least one silica source selected from the group consisting of silica fine powder and silica sand that is chemically bonded to the component and hydrated in water under predetermined conditions;
(c) about 5 to 15 parts by weight of spray-dried sodium silicate hydrate or sodium hydroxide as a water reducing agent; and (d) per 100 parts by weight of components (a), (b), and (c). A cement composition comprising about 15 to 20 parts by weight of water.