RU2136845C1 - Grouting mortar - Google Patents

Abstract

FIELD: oil and gas production. SUBSTANCE: grouting mortar contains preliminarily calcined in spray drier at 550-650 C distiller liquid obtained as waste in distillation stage of sodium hydroxide production. This mortar constituent is composed of, wt %: CaCl₂ 69.40-65.80, CaSO₄ 0.05-0.10, Ca(OH)₂ 0.05-0.10, NaCl 32.15-38.50. Mortar is composed of, wt %: cement 43.5-62/5, distiller liquid 0.7-6.2, nonsorted microspheres 6.5-19.9, and water - the balance, cement-to-microspheres ratio ranging from 75:25 to 90:10. Microspheres are composed of, wt %: SiO₂ 50-60, Al₂O₃ 25-35, Fe₂O₃ 1.8-2.0, CaO 1.0-1.5, MgO 0.5-1.5, Na₂O 0.3- 1.5, K₂O 0.2-2.9, and minor components 0.3-1.4. EFFECT: reduced density of mortar, increased strength of cement stone, and reduced water loss. 2 tbl

Description

 The invention relates to the oil and gas industry, in particular, the production of cement-based cement slurry, including calcium, sodium, and water salts, and can be used in well cementing.

 Known grouting solution for killing and cementing wells, containing cement, condensed sulphite-alcohol stillage, calcium chloride and water [1].

The disadvantage of this solution is its high density (1850-1950 kg / m ³ ) and the insufficient strength of the stone.

 Also known is cement slurry, including, wt.%: Cement 1.0; calcium chloride 0.05-0.10; water 0.50-0.70 [2]. The well-known cement slurry, although it has sufficient strength, however, the high content of calcium chloride contributes to the intensive crack formation of cement stone in the hardening process. In addition, the cost of the solution as a whole increases due to the high price of calcium chloride.

 The closest technical solution to the claimed - the prototype - is cement slurry, including Portland cement, water, waste production of soda ash [3]. The main disadvantage of the known mortar is the low strength characteristics of the stone, difficulties with the delivery of the salt component - distillation fluid, the large water separation of the grout, due to which a large amount of cement mortar penetrates into the formation, which negatively affects the flow inflow from the formation.

 The aim of the invention is to increase the strength of cement stone, reducing water separation.

The goal is achieved in that the plugging solution as salt components are used precalcined in a spray drier at 550-650 ^o C waste soda ash production distillation step - distiller fluid - the following composition: wt%.
CaCl ₂ - 59.40-65.80
CaSO ₄ - 0.05-0.10
Ca (OH) ₂ - 0.05-0.10
NaCl - 32.15-38.50
and the cement slurry contains microspheres unclassified with the following content of components, wt.%:
Cement - 43.5-62.5
Distiller liquid - 0.7 - 6.2
Unclassified microspheres - 6.5 - 19.9
Water - The rest,
and the ratio of cement: microspheres (75-90) :( 10-25).

Unclassified microspheres are an integral part of the ash that forms when coal is burned. Microspheres are hollow spherical particles with a diameter of 30 to 350 microns, with a wall thickness of 2 to 10 microns. Particles are regular spheres with continuous non-porous walls. The inner part of the particles is filled mainly with nitrogen and carbon dioxide. Microspheres have a low density (bulk density 0.25-0.5 g / cm ³ ), high compressive strength (up to 50 MPa), and are resistant to acids.

Chemical composition, wt.%:
SiO ₂ - 50-60
Al ₂ O ₃ - 25-35
Fe ₂ O ₃ - 1.8-2.0
CaO - 1-5
MgO - 0.5-1.5
Na ₂ O - 0.3 - 1.5
K ₂ O - 0.2-2.9
P.p.p. - 0.3-1.4.

 Thus, in the present invention uses new ingredients, which gives reason to assert that the proposed solution meets the criterion of "novelty."

The scientific, technical and patent literature has not previously provided information on the use of microspheres unclassified in the preparation of cement slurries based on Portland cement with a salt composition. It is known to use glass and ceramic balls and gas-filled microballoons [4, 5]. The use of microspheres gives a previously unknown effect of increasing the strength of a stone, not previously achieved by the use of microballoons. This is due to the fact that the microsphere is 50-60% SiO ₂ and has an amorphous structure, due to which their reaction activity in an alkaline environment increases, which appears during the hydration of Portland cement or other binders. As a result of this, hydration products begin to crystallize from a supersaturated solution on the surface of the microspheres, i.e. they (microspheres) are active components in the composition of the hardening grouting mortar and thus make an additional contribution to increasing the strength of the stone. Microballoons used earlier have a hydrophobic surface; therefore, they do not form chemical bonds with hardening products and are inert in the composition of the stone. The same applies to glass and ceramic balls. The use of balls due to their hydrophobicity leads to an increase in the water-cement ratio (water content of solutions), therefore, an increase in the porosity of the stone and a sharp deterioration in strength are inevitable. In addition, solutions with microballoons and balls exfoliate due to the low concentration of the structure-forming phase in the solution (surfacing of lightening additives). Thus, the foregoing indicates the conformity of the claimed invention to the criterion of "inventive step".

An example implementation of the invention
To prepare a solution of composition 6 (Table 1), 1000 g of a solution is prepared, including 513 g of cement, 64 g of a dry salt composition, 128 g of microspheres and 295 g of water. The grouting mixture is prepared as follows. First, the salt component is dissolved in water, and then a mixture of cement and microspheres is closed on this solution. The water-solid ratio is 0.46. The resulting solution is measured according to GOST spreadability and density. Then samples of beams are poured to determine the strength of the stone. The simplicity of the preparation of the solution and the control of properties indicate compliance with its criterion of "practical applicability".

To prepare the cement slurry used the salt composition of the following composition, wt.%:
CaCl ₂ - 61.6,
CaSO ₄ - 0.1
NaCl - 33.4
Ca (OH) - 0.18
The prepared grouting mixtures and their indicators are shown in tables 1, 2.

 Based on the data presented in the tables, it can be concluded that the inventive cement slurry using soda in the distillation stage as a salt component, additionally containing unclassified microspheres, has a significantly low density and exceeds the well-known grouting mortar in stone strength. In this case, the solution has a low water separation. The setting time of the solution is within the requirements of GOST 1581-91. The best performance grouting mixtures are given in experiments N 4,5. In addition, the use of soda production wastes to a certain extent solves the issue of their disposal and, in part, environmental problems.

Sources of information
1. Rakhimkulov R.Sh., Sharipov A.U. The use of surfactants to regulate the technological properties of cement slurry and stone. Oil industry, 1976, N 7.

 2. A.S. USSR N 967969, class E 21 B 33/188, 1978.

 3. RF patent N 2059792, cl. E 21 B 33/138, 1996.

 4. US patent N 3804058, cl. 166-292, published. 1974.

 5. Krylov V. I. Isolation of absorbing formations in deep wells. M .: Nedra, 1980.S. 132-134

Claims (1)

Cement slurry containing cement, calcined at 550 - 650 ^o C waste soda ash production - distiller liquid of the following composition, wt.%:
CaCl ₂ - 59.4 - 65.80
CaSO ₄ - 0.05 - 0.10
NaCl - 32.15 - 38.50
Ca (OH) ₂ - 0.05 - 0.10
unclassified microspheres, characterized in that the unclassified microspheres have a chemical composition, wt.%:
SiO ₂ - 50 - 60
Al ₂ O ₃ - 25 - 35
Fe ₂ O ₃ - 1.8 - 2.0
CaO - 1.0 - 1.5
MgO - 0.5 - 1.5
Na ₂ O - 0.3 - 1.5
K ₂ O - 0.2 - 2.9
P.p.p. - 0.3 - 1.4
while the cement slurry contains components in the following ratio, wt.%:
Cement - 43.5 - 62.5
Distiller liquid - waste from soda ash production - 0.7 - 6.2
Unclassified microspheres - 6.5 - 19.9
Water - Else
moreover, the ratio of cement: microspheres is (75 - 90): (10 - 25).

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