RU2026960C1 - Method for production of grouting mixture - Google Patents

Abstract

FIELD: gas and oil producing industry. SUBSTANCE: method for production of grouting mixture includes mixing of fly ash with quicklime and letting it stand. Moisture content of fly ash is decreased down to 2-3%. Added to mixture is portland cement. Mixture is subjected to mechanical action at impact frequency of 2-5 per 10^-3s. Components are taken in the following amounts, mas. % : portland cement 34-35; fly ash 38-50 and quicklime 5-27. EFFECT: higher efficiency. 1 tbl

Description

 The invention relates to the oil and gas industry, in particular to building materials, and can be used to obtain grouting mixtures for cementing wells, the products of which contain aggressive acidic components.

 A known method of producing a cement-ash mixture, which consists in mixing a pulverized mixture with Portland cement in various ratios [1].

 Closest to the claimed combination of features is a method of producing an expanding grouting mixture, including mixing fly ash, quicklime, Portland cement and subsequent mechanical impact - fine grinding of the components, increasing their activity [2].

 The disadvantages of this method (prototype) is the need for drying wet fly ash and insufficient activation of the components of the mixture in the process of fine grinding. The drying process of the ash causes environmental pollution, and the lack of activity of the components does not provide a cement slurry and cement stone with high physical and mechanical properties.

 The purpose of the invention is to improve the quality of the fastening of wells by improving the physico-mechanical properties of the cement slurry and the formed stone by preserving the expanding properties of the stone and increasing its corrosion resistance, and implementing an environmentally friendly technology for producing the grouting mixture.

To achieve this goal in the claimed method of producing a cement mixture, including mixing fly ash, quicklime and Portland cement, followed by mechanical action, fly ash is pre-mixed with quicklime, withstand, and the mechanical effect is carried out at a shock frequency of 2 - 5 for 10 ^{- 3} sec The components are used in the following ratio, wt. %: Portland cement 35 - 45 Fly ash 38 - 50 Quicklime 5 - 27 which distinguishes the claimed technical solution from the prototype.

 PRI me R. A method of obtaining a cement mixture is as follows. Fly ash is pre-mixed with quicklime and incubated for 3 to 4 hours. Due to the exothermic reaction, fly ash is dried. During the indicated time, the humidity of fly ash decreases to 2–3%, which is sufficient to prepare the mixture and a further decrease in humidity is not economically profitable. Drying fly ash is carried out directly in the process of preparing a dry cement mixture and does not require additional costs. Portland cement is added to the prepared mixture. Moreover, the content of the components is maintained in the stated proportions.

The grouting mixture is subjected to mechanical action by powerful pulses at a shock frequency of 2 - 5 for 10 ^-3 s in the disintegrator. Due to the repeated collision of particles, the mechanochemical activation of the mixture subjected to mechanical processing occurs, which increases the reactivity of the cement slurry.

As components of the cement mixture were used:
- Portland cement PCT D20-100 Novotroitsky cement plant;
- fly ash, for example, Aktobe CHP, having the following physical and mechanical properties:
chemical composition,%: SiO ₂ 56.0; Al ₂ O ₃ 26.7; Fe ₂ O ₃ 4.58; CaO 3.64; MgO 1.44; SO ₃ 2,52 and others 5.12.

density 2.06 g / cm ³ ;
specific surface area 4310 cm ² / g;
the residue on a sieve N 008 - 15%. According to GOST 25818-83, fly ash corresponds to type II (Technology for the preparation of grouting mixtures by the disintegrator method with various physical and mechanical properties. Overview information. Engineering and technology for exploration. Organization of production. M .: VIEMS, 1979, p. 2);
quicklime according to GOST 9179-77 refers to the calcium type of the 2nd and 3rd grades.

 It is possible to use fly ash of other CHP plants having similar physicochemical properties.

To conduct the study were taken plugging mixtures with different contents of components received in different modes mechano-chemical action, and shut tap water, specified physical and mechanical properties of cement slurry and stone in hardening conditions at 22, 60 and 75 ^{° C} and determined boundary values component contents are shown in the table.

PRI me R. To prepare the cement slurry were taken 500 g of tap water and 1000 g of dry cement mixture containing the components, wt. % / g /: Portland cement 42/420 / Fly ash 38/380 / Quicklime 20/200 /
The dry cement mixture was prepared by the claimed method and closed on tap water (see experiment 4 tables).

 The sequence of preparation of the remaining proposed mixtures and cement slurries indicated in the table is similar to the above and differs only in the content of the components.

 The preparation of cement slurry was carried out according to GOST 26798.0-85. The main technological parameters of the solution: (density, spreadability and setting time) were determined according to GOST 26798.1-85.

 The sedimentation stability of the cement slurry was determined using the device according to the amount of water discharge for the period from the moment of preparation to the formation of a crystallization structure, which allows taking into account the influence of changes in the threshold pressure in it during hardening.

 Strength limits of cement stone were determined according to GOST 26798.2-85.

Corrosion resistance to _a cement paste was determined as the ratio of compressive strength balochek twin stored for 2 and 180 days under normal conditions in a humid environment at a temperature of 22 ± 3 ° ^C and a pressure of 0.1 MPa, and in aggressive environments (in gas) containing 4.5% in the total volume of hydrogen sulfide and 1% carbon dioxide at a temperature of 22 ± 3 ^о С and a pressure of 3.5 MPa.

 The expansion of cement stone was determined as the ratio of the volume of the hardened mass to the volume of grouting mortar after its preparation with the help of a device that allows you to monitor the change in the volume of grouting mortar during hardening (Bulatov A.I. and Daniushevsky V.S. Grouting materials. M .: Nedra, 1987, p. 138 - 139).

 The results of laboratory tests are presented in the table.

 The analysis of which shows that the grouting mixture prepared by the known method in known ratios of components when mixed with water (experiments 15-17) forms a grouting mortar with satisfactory technological parameters, but low sedimentation stability (sludge 2%), low strength of the formed stone (1 , 6 - 3.6 MPa), low corrosion resistance of the latter, reaching 0.33 - 0.37. The expansion of the stone is 2.0 - 6.0%.

 The grouting mixture prepared by the present method, within the claimed limits of the content of the components (experiments 1-6) forms a sedimentation-stable grouting mortar with similar water-mixture ratios with satisfactory technological parameters.

 The stone has increased strength values (2.2 - 4.6 MPa), corrosion resistance (0.47 - 0.51). The expansion of the stone is 1.5 - 2%.

 The table shows that the content of fly ash is optimal in the range of 38 - 50 wt. % When the content of fly ash more than 50 wt. % worsens the strength of the cement stone, and cement stone sedimentation unstable (experiment 14). When the content of fly ash less than 30 wt. % (experiment 13) the corrosion resistance of the stone at the level of the prototype.

 The content of Portland cement is less than 35 wt. % does not provide cement stone strength greater than that of the prototype (experiment 11), with a Portland cement content of more than 45 wt. % (experiment 12), the mobility of the solution worsens (the spreadability along the cone of the AzNII is 16 cm).

 With the above optimal contents of fly ash and Portland cement, the lime content is optimal in the range of 5 - 27 wt. %

The table shows the effect of the mechanical action on the mixture; the impact frequency should be considered optimal in the range of 2–5 for 10 ^–3 s.

When the impact frequency is less than 2 for 10 ⁻³ s, the physicomechanical properties of the cement slurry and mixture are at the prototype level (experiments 7 and 8), more than 5 (experiment 9 and 10), no improvement in physicomechanical properties is observed.

 Grouting mortar based on dry lightweight cement slurry prepared by the claimed method has a relatively low water demand (in the range of 0.49 - 0.52) with satisfactory technological parameters.

 In the claimed method, thermal drying of the components is excluded, which ensures the preservation of the environmental situation in the area of preparation of dry cement mixtures. The use of cement slurry prepared in this way ensures the creation of high-strength corrosion-resistant expanding cement stone in the annular space, which increases the durability of the well support and increases their production capabilities.

Claims (1)

METHOD FOR PRODUCING A TUGGLING MIXTURE, including mixing fly ash, quicklime and Portland cement followed by mechanical action, characterized in that the fly ash is pre-mixed with quicklime and incubated, and mechanical action is carried out at a particle impact frequency of 2 - 5 in 10 ^{- 3} s, while the components of the mixture are used in the following ratio, wt.%:
Portland cement - 35 - 45
Fly ash - 38 - 50
Quicklime - 5 - 27

Images