RU2306327C1 - Grouting mortar for cementing gas-oil wells - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention, in particular, relates to gas-oil wells with horizontal boreholes and provides grouting mortar comprising, wt %: grouting Portland cement 43.1-43.8, gypsum "G16" 2-2.3, alumina cement "GTs-40" 4.2-4.5, potash 0.4-0.5, microsilica 2-2.3, sand 43.1-43.8 and, additionally, "Sulfacell 25" 0.2-0.3, super-plasticizer "S-3" 0.2-0.3, plasticizer Walocel MKX 40000 PF01 0.2-0.3, and water-based organosilicon compound "GIFOB" 3.2-3.4, wherein water/solids ratio is maintained equal to 0.35-0.4.

EFFECT: increased waterproofness of grouting stone and enhanced efficiency of gas-oil well casing.

3 tbl, 5 ex

Description

The invention relates to the oil and gas industry and can be used for fastening gas and oil wells mainly with horizontal shafts.

A well-known grouting composition for fastening flat and horizontal wells (RF patent No. 2256775, IPC EV 33/138). The grouting composition contains grouting cement, a stabilizing reagent, a mineral additive and water. As a mineral additive, the composition contains sodium chloride or potassium chloride, with the following content of components, parts by weight: cement slurry 100, stabilizing reagent 0.2-1.2, mineral additive 2.0-3.0, water 40- fifty. As a stabilizing reagent, resistant to polymineral aggression, the grouting composition may contain Sulfacell C or a complex reagent-reducing agent for water loss of the KRC. The grouting composition with sulfacell C additionally contains an antifoam. The disadvantage of this composition is the lack of water resistance and low strength properties of the resulting cement stone.

A well-known cement slurry for cementing gas and oil wells and the method of its preparation, adopted as a prototype (RF patent No. 2057250, IPC EV 33/138). The solution contains grouting cement, silica fume - a waste from the production of silica fume and water. If necessary, gypsum, a weighting agent, a dispersant and a setting time regulator can be introduced into the solution. The disadvantage of this solution is the lack of water resistance of the resulting cement stone.

The technical result of the invention is to increase the waterproof properties of cement stone obtained from the proposed solution.

The technical result is achieved in that in a cement slurry for cementing oil and gas wells containing cement Portland cement as a binder, gypsum as an accelerator for building strength, silica fume as a strengthening additive, setting time regulators, sand as a filler, water as a mixing fluid, according to According to the invention, it contains sulfacell 25 as a water-holding additive, as an adjuster of setting time, it contains alumina cement and potash, as a pla it contains C-3 superplasticizer and Walocel MKX 40000 PF01 plasticizer, as a water-repellent agent, water-based organosilicon HIFOB in the following ratio of ingredients, wt.%:

Grouting Portland cement 43.1-43.8 Gypsum G16 2-2.3 Alumina cement HZ-40 4.2-4.5 Potash 0.4-0.5 Silica fume 2-2.3 Sand 43.1-43.8 Walocel MKX 40,000 PF01 0.2-0.3 Sulfacell 25 0.2-0.3 Superplasticizer S-3 0.2-0.3 GIFOF 3.2-3.4

while the water-solid ratio is maintained equal to 0.35-0.4.

The application of the proposed method in comparison with the prototype will improve the waterproof properties of the cement stone obtained from the proposed cement slurry.

A cement slurry for cementing gas and oil wells is prepared as follows: the following components are mixed in dry form in the required proportions.

The ratio of the components is set in the range, wt.%:

Grouting Portland cement 43.1-43.8 Gypsum G16 2-2.3 Alumina cement HZ-40 4.2-4.5 Potash 0.4-0.5 Silica fume 2-2.3 Sand 43.1-43.8 Walocel MKX 40,000 PF01 0.2-0.3 Superplasticizer S-3 0.2-0.3 GIFOF 3.2-3.4

Separately, Sulfacell 25 is added to the mixing liquid (water) in an amount of 0.2-0.3 wt.% For its structuring. Then, with constant stirring, all remaining dry-mixed ingredients are added to water with sulfacell 25. In this case, the water-solid ratio is maintained equal to 0.35-0.4.

The boundaries of adding to the composition of various ingredients are selected based on the necessary strength and waterproofness of the cement stone to create and maintain the necessary water-holding properties.

Portland cement grade M-400 was used as a binder. Portland cement is the hydraulic binder most commonly used in modern construction. Get together by fine grinding clinker and gypsum (sometimes some additives). In addition to conventional Portland cement, hydrophobic, plasticized, sulfate-resistant, white and colored Portland cement, etc. are produced.

In the experiment, high-strength gypsum G-16 for special purposes was used in the experiment. G-16 gypsum is also an additive, self-expanding upon hardening of the solution, which helps to increase the strength properties of the resulting cement stone. The volume of packaging is 38 kg. GVVS-16 high-strength special-purpose gypsum is used in the porcelain-faience and ceramic industries for the manufacture of molds and models, in the oil industry for plugging wells, as well as in the manufacture of molded products, decorative plates, parts for them, cornices, ventilation grills and other building products. It differs from other binders in its increased strength (130-160 kgf / cm ² ) with two-hour exposure, the best degree of grinding, and the absence of extraneous impurities, including metal impurities (they contain up to 0.001%).

HZ-40 alumina cement was used as a setting time regulator. In addition, it helps to reduce the shrinkage of cement stone during hardening and helps to increase water resistance. Alumina cement is a quick-setting hydraulic binder obtained by firing a raw mix of bauxite and limestone or lime, followed by fine grinding of the product. It is characterized by high corrosion resistance, water tightness and fire resistance; it is applied at urgent restoration, repair and other special works, and also for receiving heat-resistant concrete. Alumina cement was accepted and tested with properties according to GOST 969-91 (ST SEV 6826-89) Alumina and high alumina cement. Technical conditions

Potash according to GOST 10690-73 was also used as regulators of the setting time for the experiment. Potassium carbonate technical (potash). Technical conditions Potassium carbonate (potash) has the chemical formula K ₂ CO ₃ . These are colorless crystals. Very hygroscopic. It is soluble in water. Used in the manufacture of liquid soap, refractory and crystal glass. One of the reasons preventing the widespread use of potash as an accelerator of setting and hardening is the very fast setting of cement caused by it. For most Portland cement, its addition causes the setting to begin in 10-15 minutes, which virtually eliminates the centralized preparation of concrete and mortar with the addition of potash.

Silica fume was used as a hardening additive. Silica dust (KP), also called silica fume or microfiller, is a by-product of metallurgical production in the smelting of ferrosilicon and its alloys, resulting from the recovery of high-purity quartz by carbon in electric furnaces. In the process of smelting silicon alloys, some of the silicon monoxide SiO goes into a gaseous state and, subject to oxidation and condensation, forms an extremely small product in the form of spherical particles with a high content of amorphous silica. New opportunities for using KP are closely related to progress in the field of creating effective superplasticizers - their combination gave impetus to the creation of new generation concrete with high strength (from 60 to 150 MPa), increased workability and durability. Silica dust, as stated above, is very small, spherical particles of amorphous silica having an average surface area of about 20 m ² / g. Silica dust can be obtained in three states - natural and compacted, as well as in the form of an aqueous suspension (about 50%). The density of the KP in its natural state is approximately 2.2 g / cm ³ (Portland cement - 3.1 g / cm ³ ), and the bulk density in the loose state is 130-430 kg / m ³ (cement - 1500 kg / m ³ ). Due to compaction, it is possible to increase the density to 480-720 kg / m ³ . A very small particle size distribution and a significant specific surface area of amorphous silica grains determine the high pozzolanic properties and the positive effect of KP on the properties of concrete.

Sand was used as a filler. Sand - small-detrital loose sedimentary rock, consisting of not less than 50% of quartz grains, feldspars and other minerals and rock fragments of 0.05-2 mm in size; contains an admixture of silt and clay particles. It is used in construction and glass industry. For the experiment, it was taken according to GOST 6139-91 (ST SEV 6951-89) Standard sand for cement testing. Technical conditions

As a plasticizer, C-3 superplasticizer was used. It is an organic synthetic substance based on the condensation product of naphthalenesulfonic acid and formaldehyde with a specific ratio of fractions with different number average molecular weights. Sodium polynaphthalenemethylene sulfonate or sodium methylenebis (naphthalenesulfonate). Contains impurities of sodium sulfate and tarry substances. According to the classification GOST 24211 S-3 refers to the plasticizing-water-reducing form - superplasticizers (TU 5870-002-58042865-03 with amendment No. 1). Superplasticizer S-3 is intended: for a sharp increase in workability and formability of concrete mixtures without reducing the strength and durability of concrete (with a constant water-cement ratio); for a significant increase in physico-mechanical properties and construction and technical properties of concrete (while reducing water consumption and constant workability); to increase the workability of concrete mixtures and to increase the physical and mechanical properties and construction and technical properties of concrete (while reducing the water-cement ratio and increasing workability); to reduce cement consumption without reducing the workability of the concrete mixture, physical and mechanical properties and construction and technical properties of concrete (while reducing the water content of the concrete mixture). Superplasticizer C-3 is also the basis for the manufacture of complex additives of various kinds. Superplasticizer S-3 is recommended for use: in the construction of all types of structures from monolithic heavy concrete of classes of compressive strength B15 (M200) and higher; in the manufacture of all types of prefabricated reinforced concrete structures and concrete products from heavy concrete, classes of compressive strength B15 (M200) and higher; during the construction of all types of structures from monolithic fine-grained concrete of classes of strength B10 (M150) and higher; in the manufacture of all types of prefabricated reinforced concrete structures and concrete products on porous aggregates of classes of compressive strength B7.5 (M100) and higher; if necessary, the production of concrete mixtures using non-standard aggregates, including fine sands; when erecting monolithic structures using tensile cement or using mineral expanding additives; in the construction of monolithic structures, the manufacture of precast concrete products from heat-resistant concrete on Portland cement, slag Portland cement and alumina cement. Superplasticizer C-3 is made in the form of a powder (microgranules) and in the form of an aqueous solution.

As a plasticizer, Walocel MKX 40000 PF01 was used. Walocel - methyl cellulose of the German concern Bayer. The German company Wolf Cellulosexics, which is part of the Bayer Group, is one of the world's leading manufacturers of two types of methyl cellulose (MC): methyl hydroxyethyl cellulose (MCEC); methylhydroxypropyl cellulose (MGPTs) under the brand name Walocel (Valotsel® M). Depending on the purpose, a number of modifications of the MC with various properties are produced. There are five product lines for the brand, but using the MHEC Walocel MKX 40,000 PF01 has yielded the best results. Walocel MKX 40000 PF01 - High-esterification MPEG with a wide range of applications, especially recommended for systems with mineral binders, such as tile adhesives, masonry mortars, putties and plasters.

Properties Walocel (Valocel® M) ionogenicity Nonionic surface activity High solubility soluble in cold water; in some cases, soluble in organic solvents water retention varies widely depending on the individual product the effect of temperature increase on the solution the viscosity first drops, then increases until the gel forms; the process is reversible pH effect high solubility over a wide pH range the effect of polyvalent metal ions no complexation and flocculation occurs film formation good film-forming properties

In dry construction mixtures, MC is used in very low concentrations (0.02-0.7%), but precisely because of MC, it is possible to control such quality parameters as elasticity, shape stability, water retention and adhesion to various surfaces. Valocel M brand products are ideally suited for regulating the rheological properties and consistency of building materials. Valotsel M provides high and stable with respect to temperature effects water retention. When Valocel M is added, construction materials become easy to work, do not stick to the tool, and remain suitable for a long time. The correct selection of the brand of ether Valotsel M is crucial to achieve the optimal result when using MC in one form or another of dry construction mixtures. The main characteristics of Valocell M are viscosity, particle size, and displacement. The viscosity of Valocel M can vary from 400 mPa · s to 70,000 mPa · s. Viscosity measurements are usually performed on a Haake RV 100 viscometer at a strain rate of 2.55 1 / s at 20 ° C in a 2% aqueous solution. For products with a viscosity below 1000 mPa · s, viscosity is measured with a Heppler viscometer (2% solution). The properties of Valocel M are largely based on its specific behavior in aqueous solution. Valocel M solutions are pseudoplastic, and at high concentrations thixotropic. The degree of substitution (degree of esterification) is the number of esterified hydroxyl groups per one (glucose) unit of the polymer cellulose molecule. The maximum possible degree of substitution is 3. For the manufacture of dry mixtures using MC with a degree of substitution of 1.7-2.4. According to the size of particles (dispersion) Valoceli M is divided into: granules (index G); powders (index P); fine powders (PF index); ultrafine powders (PP index). Depending on the application, it is necessary to use Valotseli M with different particle sizes. Granules are used in cases where MC is directly dissolved in water. Powders are better suited to be added to dry mixes. The higher the dispersion of Valocel’s powder M, the higher its water retention capacity in building materials. The main properties of Valocel M are indicated in the title.

Properties Walocel MKX 40000 PF01 Chemical name MHEC The form fine powder Viscosity, MPa · s 42000-47000 Active substance min 94% Degree of substitution 1.75-2.00

Sulfacell grade 25 was used as a water-retaining additive, as well as a structure-forming agent. It is a cellulose ether obtained by reacting activated cellulose with ethylene oxide. Sulfacell 25 is highly soluble in water with the formation of pseudoplastic solutions. Due to its non-ionic nature, the product has a wide range of compatibility with other water-soluble substances. Depending on the content of the basic substance, two product modifications are available (Sulfacell 1 and Sulfacell 2), each of which includes eight grades with different viscosity characteristics. Areas of use for Sulfacella - oil and gas, chemical, paint and varnish, textile, printing, construction, engineering industries, as well as the production of household chemicals. In the oil and gas production industries, Sulfacell is used as a reagent - a stabilizer of clay drilling fluids, a reagent to reduce filtration and regulate the rheological properties of clayless drilling fluids, flushing fluids and grouting cements, as well as a reagent to limit water inflows and increase oil recovery. In the chemical industry, Sulfacell is used as an emulsifier and protective colloid in the polymerization of vinyl monomers; in the textile, printing and varnish and paint industries, Sulfacell is used as a thickener for printing inks and water-based pigments; in the construction industry - in the production of dry mortar and putty. Sulfacell benefits: resistance to polymineral aggression; stability at temperatures up to 120 ° C; low filtration values and optimal rheological properties; a wide range of compatibility with other water-soluble polymers; high water retention capacity.

Physico-chemical characteristics of the product Sulfacell-2 grade 25 Appearance Fibrous mass, powder or granules of white, slightly yellow or grayish color Mass fraction of the main substance in the technical product,%, not less than 65 Dynamic viscosity of an aqueous solution of Sulfacell with a mass fraction of a technical product of 2%, MPa.s no more than 50 Solubility in water,%, not less than 98

Packing: Polypropylene bags with polyethylene liner, 25 kg net.

GIFOF was used as a water repellent. GIFOB silicone-based water-based protective agent - designed to protect building materials, structures, buildings and architectural objects from water saturation. Appearance - colorless or slightly colored liquid without visible inclusions and odor. The reaction of the medium (pH of the aqueous extract): 12-13. Water absorption by weight of not more than 2.5%. Density of at least 1.02 g / cm ^3. The dry residue is not more than 2.5%. GIFOF does not contain organic solvents and does not emit harmful fumes. Non toxic Fireproof. The consumption of a protective agent for other types of material is determined empirically until the liquid is not absorbed. Advantages of the protective agent GIFOF: gives the treated surface of the building material water-repellent properties. Does not change the vapor and air permeability of the material. The protective coating prevents the carbonization of concrete, which occurs as a result of exposure to carbon dioxide and water vapor in structures, which weakens the protective properties of concrete in relation to reinforcement (prevents reinforced concrete structures from penetrating aggressive condensate through the protective layers of concrete to the reinforcement). Allows you to save the original thermophysical properties of building materials in the wet season. Due to the absence of organic solvents in HYFOB, it can be used when working indoors, prevents efflorescence and leaks. The protective agent GIFOF and its treatment are cheaper than other and foreign compounds and methods of protecting building materials from water. It does not require complicated application and kneading technology. Made from domestic raw materials.

In laboratory conditions, grouting mortar was prepared on a laboratory mixer according to GOST 26798.0-2001. The main parameters of the cement slurry (density, spreadability, strength) were determined in accordance with GOST 26798.1-2001. The setting time was determined using a Vic needle.

For laboratory studies, cement slurries were prepared with the component compositions shown in the examples below.

Example 1. Prepared composition with a ratio of components:

Component Mass g Mac.% Grouting Portland cement 980.00 44.1 Gypsum G16 43.00 1.9 Alumina cement HZ-40 92.00 4.1 Potash 7.00 0.3 Silica fume 42.00 1.9 Sand 980.00 44.1 Walocel MKX 40000 PF01 3.00 0.1 Sulfacell 25 3.00 0.1 Superplasticizer S-3 3.00 0.1 GIFOF 71.00 3.2 2224.00 100.0

The remaining dry ingredients premixed with each other were added to the water with added sulfacell 25 with constant stirring. The water-solid ratio was maintained equal to 0.42 (weight of added water 934 g). Setting start time 7 h 20 min. Setting time 13 hours 30 minutes This setting time is insufficient for well plugging, as the strength of the cement stone will be reduced due to interaction with the wellbore fluid. Strength indicators were tested on samples with dimensions of 40 × 40 × 150 mm. The uniaxial compression strength of the sample is 11.6 MPa, the bending strength is 1.1 MPa. Strength is not high enough. The speed of curing is low. Significant shrinkage is visible on the sample after holding for 2 days, which is unacceptable. More additives are needed to prevent shrinkage of the cement. To accelerate the curing, more hardening accelerators are needed. Water retention 90%, water permeability 1 · 10 ^-5 microns ² . These indicators are insufficient, therefore, the addition of water repellents is necessary. The resulting solution has a high spreadability (23 divisions), which will lead to a decrease in the quality of plugging, therefore, a greater number of plasticizers must be introduced into the solution.

Example 2. Prepared composition with a ratio of components:

Component Mass g Mac.% Grouting Portland cement 1000,00 43,4 Gypsum G16 50.00 2.2 Alumina cement HZ-40 100.00 4.3 Silica fume 50.00 2.2 Sand 1000,00 43,4 Potash 10.00 0.4 Walocel MKX 40000 PF01 5.00 0.2 Sulfacell 25 5.00 0.2 Superplasticizer S-3 5.00 0.2 GIFOF 77.00 3.3 2302.00 100.0

The remaining dry ingredients premixed with each other were added to the water with added sulfacell 25 with constant stirring. The water-solid ratio was maintained equal to 0.4 (weight of added water 903.2 g). Setting start time 5 h 20 min. Setting time is 12 hours 30 minutes. This setting time is sufficient for well plugging. Strength indicators were tested on samples with dimensions of 40 × 40 × 150 mm. The uniaxial compression strength of the sample is 13.6 MPa, the bending strength is 1.73 MPa. Strength is quite high. The speed of curing is acceptable. On the sample after exposure for 2 days, slight shrinkage is visible, which is acceptable. To accelerate the set of strength, it is possible to add more hardening accelerators. Water retention 92%, water permeability 2 · 10 ^-5 μm ² . These indicators are sufficient, but the addition of water repellents is necessary. The resulting solution has a normal flowability (21 divisions), which may lead to a decrease in the quality of plugging, so a larger number of plasticizers can be introduced into the solution.

Example 3. Prepared composition with a ratio of components:

Component Mass g Mac.% Grouting Portland cement 1010.00 43.1 Gypsum G16 55.00 2,3 Alumina cement HZ-40 105.00 4,5 Silica fume 55.00 2,3 Sand 1010.00 43.1 Potash 12.00 0.5 Walocel MKX 40000 PF01 6.00 0.3 Sulfacell 25 6.00 0.3 Superplasticizer S-3 6.00 0.3 GIFOF 80.00 3.4 2345.00 100.0

The remaining dry ingredients premixed with each other were added to the water with added sulfacell 25 with constant stirring. In this case, the water-solid ratio was maintained equal to 0.375, that is, water was added to 863.25 g. The setting onset time was 4 hours 30 minutes. Setting time is 6 hours 30 minutes. This setting time is the most rational for high-quality plugging of the well, since due to the interaction with the well fluid, the strength of the obtained cement stone will practically not be reduced. Strength indicators were tested on samples with dimensions of 40 × 40 × 150 mm. The uniaxial compression strength of the sample is 20.74 MPa, the bending strength is 2 MPa. Strength is quite high. The speed of curing is the most rational. After exposure to 28 days, there is practically no shrinkage in the sample, which is acceptable. The amount of additives to prevent shrinkage of cement stone is normal. To accelerate the curing, there is no need to add more hardening accelerators. Water retention (on the ring) 97.5%, water permeability 3 · 10 ^-5 μm ² . These indicators are sufficient, therefore, the addition of water repellents is not needed. The resulting solution has an acceptable flowability (17 divisions), so there is no need to introduce more plasticizers. A high level of water retention indicates a lack of hydration, which will positively affect the quality of the cement stone obtained.

Example 4. Prepared composition with a ratio of components:

Component Mass g Mac.% Grouting Portland cement 1010.00 43.1 Gypsum G16 55.00 2,3 Alumina cement HZ-40 105.00 4,5 Silica fume 55.00 2,3 Sand 1010.00 43.1 Potash 12.00 0.5 Walocel MKX 40000 PF01 6.00 0.3 Sulfacell 25 6.00 0.3 Superplasticizer S-3 6.00 0.3 GIFOF 80.00 3.4 2345.00 100.0

The remaining dry ingredients premixed with each other were added to the water with added sulfacell 25 with constant stirring. In this case, the water-solid ratio was maintained equal to 0.35, that is, water was added 820.75 g. The setting onset time was 3 hours 30 minutes. Setting time 5 h 30 min. This setting time is not the most rational for high-quality plugging of the well, since there is the possibility of solidification of the solution when supplied through the well, but it is possible with a good organization of work. Strength indicators were tested on samples with dimensions of 40 × 40 × 150 mm. The uniaxial compression strength of the sample is 21 MPa, the bending strength is 2.05 MPa. Strength is quite high. After exposure to 28 days, there is practically no shrinkage in the sample, which is acceptable. The amount of additives to prevent shrinkage of cement stone is normal, as in the previous example, so adding them more does not make sense. To accelerate the curing, there is no need to add more hardening accelerators, since the curing speed is high. Water retention (on the ring) 97.5%, water permeability 4 · 10 ^-5 μm ² . These indicators are sufficient, therefore, the addition of water repellents is not needed. The resulting solution has an acceptable flowability (17 divisions), so there is no need to introduce more plasticizers.

Example 5. Prepared composition with a ratio of components:

Component Mass g Mac.% Grouting Portland cement 1020.00 42.8 Gypsum G16 58.00 2,4 Alumina cement HZ-40 108.00 4,5 Potash 14.00 0.6 Silica fume 58.00 2,4 Sand 1020.00 42.8 Walocel MKX 40000 PF01 7.00 0.3 Sulfacell 25 7.00 0.3 Superplasticizer S-3 7.00 0.3 GIFOF 82.00 3.4 2381.00 100.0

The remaining dry ingredients premixed with each other were added to the water with added sulfacell 25 with constant stirring. At the same time, the water-solid ratio was maintained equal to 0.34, that is, water was added 809.54 g. The setting onset time was 2 hours 30 minutes. Setting time 4 hours 30 minutes This setting time is not the most rational for high-quality plugging of the well, since there is the possibility of solidification of the solution when supplied through the well. Strength indicators were tested on samples with dimensions of 40 × 40 × 150 mm. The uniaxial compression strength of the sample is 21 MPa, the bending strength is 2.05 MPa. Strength is quite high. After exposure to 28 days, there is practically no shrinkage in the sample, which is acceptable. The amount of additives to prevent shrinkage of cement stone is normal, as in the previous example, so adding them more does not make sense. To accelerate the curing, there is no need to add more hardening accelerators, since the curing speed is high. Water retention (on the ring) 97.5%, water permeability 4 · 10 ^-5 μm ² . These indicators have not changed compared to the previous example, so a large addition of water repellents is not needed. The resulting solution has poor flowability (15 divisions).

Cement slurry for cementing oil and gas wells is used as follows (when fixing a certain interval of the well). Drill a well in the oil and gas reservoir to the required level. A tubing is lowered into a drilled well. To the lower part of the tubing is connected a pipe of a given diameter, which is necessary for the formation of a cement stone of a certain thickness with a given strength and the necessary water resistance properties. Then spend the plugging of the well. The required volume of the finished solution (usually determined by the volume of annular space) is pumped along the inside of the tubing. Then, a plug is installed to separate the mortar and the squeezing liquid. Squeezing fluid moves the grout and cement plug to the end of the casing. The achievement of the plug to the end of the casing is determined by the increase in pressure at the head of the well. After supplying the required amount of solution to the well, plugging is stopped. The time for applying the composition to the required tamponing interval is taken based on the start time of setting of the solution, taking into account the time of its forcing. After the shutter speed required for curing by the cement stone for the required time, depending on the temperature of the well, on the amount of cement and on the number of setting accelerators, the tubing with a fixed pipe of a given diameter at the end is removed. After that, the well is mastered by known methods and put into operation.

The use of this cement slurry for cementing gas and oil wells provides the following advantages:

- increase the water resistance of cement stone;

- increase in the efficiency of fastening gas and oil wells.

Claims (1)

Cement grouting for oil and gas wells containing binder - cement Portland cement, accelerator for gaining strength - gypsum, hardening additive - microsilica, setting time regulators, filler - sand, mixing fluid - water, characterized in that it contains gypsum G16, as timing regulators setting - alumina cement HZ-40 and potash, and additionally water-retaining additive - sulfacell 25, plasticizer superplasticizer S-3 and plasticizer Walocel MKX 40000 PF01, water repellent - organosilicon th substance water-based GIFOF in the following ratio of ingredients, wt.%: Grouting Portland cement 43.1-43.8 Gypsum G16 2-2.3 Alumina cement HZ-40 4.2-4.5 Potash 0.4-0.5 Silica fume 2-2.3 Sand 43.1-43.8 Walocel MKX 40000 PF01 0.2-0.3 Sulfacell 25 0.2-0.3 Superplasticizer S-3 0.2-0.3 GIFOF 3.2-3.4 while the water-solid ratio is maintained equal to 0.35-0.4.