RU2524774C1 - Gypsum-magnesium grouting mortar - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: proposed mortar comprises 4.01-5.13 wt % of calcium chloride CaCl₂, 7.56-9.68 wt % barium chloride BaCl₂, 8.12-11.17 wt % magnesium chloride MgCl₂·6H₂O (density of 1.32 g/cm³), 23.96-29.89 wt % aluminium sulphate Al₂(SO₄)₃·18H₂O (alumina sulphate), 1.82-2.33 wt % of magnesium oxide MgO (caustic magnesitre), 24.81-31.77 wt % of water, 9.34-29.18 wt % microdur, 0.36-0.46 wt % of super plasticiser C-3, 0.18-0.23 wt % of NTF.

EFFECT: enhanced performances and expanded applications.

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Description

The invention relates to the oil and gas industry, in particular to the field of repair and liquidation of wells in conditions of saline deposits with the presence of hydrogen sulfide, namely, when attaching casing strings, installing cut-off bridges and creating fluid-resistant insulation coatings, including in the interval of salt deposits (NaCl, MgCl ₂ , KCl), discovered reservoirs with AVPD and the presence of aggressive components H ₂ S and CO ₂ .

Known cement mixture according to A.S. SU 692982, including a binder - gypsum-alumina cement, an aqueous solution of calcium chloride (density 1.06-1.10 g / cm ³ ), a polymer additive - gipan in the following ratio of components, weight%: gypsum-alumina cement 41-51, an aqueous solution of calcium chloride (density 1.06-1.10 g / cm ³ ) - 21-26, hypane - 38-23.

This grouting mixture has the following disadvantages:

- a narrow scope, due to the instability of coagulation of hypane when mixed with an aqueous solution of calcium chloride;

- low efficiency and reliability of insulation and repair work due to poor fluidity, filterability in voids, channels, cracks and low density.

Closest to the proposed solution is cement grout according to patent RU No. 2299230, containing Microdur 261R-X, calcium chloride, aluminum sulfate, nitrilotrimethylene phosphonic acid NTF, water in the following ratio of components, weight%: Microdur 261R-X - 10-30, calcium chloride - 20-50, aluminum sulfate - 0.5-3.0, nitrilotrimethylenephosphonic acid NTF - 0.0-0.2, water - the rest.

This grouting mortar has the following disadvantages:

- narrow scope due to low technological use, due to the low density (1.4-1.5 g / cm ³ ) of cement slurry, which makes it limited to use in the construction, repair or liquidation of wells, where insulating bridges and fluid resistant screens are installed because technical conditions require the use of grouting mortars that are close in density to surrounding rocks, including salt deposits;

the insufficient number of formations of the molecularly dispersed component — calcium sulfate as a result of the chemical interaction of calcium chloride and aluminum sulfate, which plays a significant role in penetration (colmatation) when creating fluid-resistant screens.

The technical result of the invention is the expansion of the technological capabilities of the grouting mortar and the field of its application by increasing the density and spreadability of the mixture while increasing the fluid resistance and durability of the groutstone in contact with water and under conditions of manifestations of hydrogen sulfide.

The technical result is aimed at creating a gypsum-magnesia cement slurry with high resistance to destruction of a stone formed from cement slurry upon contact with water, giving it the properties of a water, salt, hydrogen sulfide-resistant element with a density close to the average surrounding density of rocks, including salt, rocks, opened by a well with low gas permeability and without cracks and fluid conduits.

The technical problem is solved in that the gypsum-magnesian grouting solution includes calcium chloride, aluminum sulfate, NTF, water, barium chloride, magnesium chloride (bischofite), magnesium oxide, which are selected on the basis of molecular calculation with their full chemical interaction, Microdur, C-3 superplasticizer and NTF (nitrilotrimethylene phosphonic acid) in the following ratio of components, wt.%:

Calcium Chloride CaCl ₂ 5.13-4.01 Barium Chloride BaCl ₂ 9.68-7.56 Magnesium Chloride MgCl ₂ · 6H ₂ O (density 1.32 g / cm ³ ) 11.17-8.12 Aluminum sulphate Al ₂ (SO ₄ ) ₃ · 18H ₂ O (alumina sulfate) 29.89-23.96 Magnesium Oxide MgO (caustic magnesite) 2.33-1.82 Water 31.77-24.81 Microdur 9.34-29.18 Superplasticizer S-3 0.46-0.36 NTF 0.23-0.18

The essence of the invention lies in the fact that the gypsum-magnesian grouting solution additionally uses the components of the active "strong" hydrochloric and sulfuric acids - barium chloride, magnesium chloride (bischofite), magnesium oxide and C-3 superplasticizer, which allows it to be given water, salt and , hydrogen sulfide-resistant properties and to obtain a sedimentation-stable high-density system close to the density of the surrounding salt rocks, with the further formation of salt-hydrogen-resistant stone with an unchanged volume for total time. This will allow reliably cementing casing strings and installing shutoff bridges, fluid-proof tires and screens in wells with manifestations of hydrogen sulfide, brine.

Gypsum-magnesia grouting mortar as a regulator of technological properties contains superplasticizer C-3 in the amount of 0.36-0.46 wt.% And NTF - 0.18-0.23 wt.%. The addition of C-3 superplasticizer to the mixture of less than 0.36 wt.% Reduces the pumpability of the mixture, and an increase in the additive of more than 0.46 wt.% Leads to delamination of the mixture. The addition of NTF to the mixture of less than 0.18 wt.% Leads to premature setting of the mixture, and an increase in the additive of more than 0.23 wt.% Leads to prolonged non-setting, which in reservoir conditions can lead to erosion of the mixture.

Gypsum-magnesia grouting mortar as a weighting agent contains barium chloride in an amount of 7.56-9.68 wt.%. The addition of barium chloride in the mixture allows you to increase the density to 1.7 g / cm ³ . The addition of barium chloride to the mixture of less than 7.56 wt.% Reduces the density, and an increase in the addition of more than 9.68 wt.% Thickens the grout.

Gypsum-magnesia cement slurry as a component forming an insoluble molecular gypsum, contains calcium chloride in an amount of 4.01-5.13 wt.%. The addition of calcium chloride to the mixture allows the formation of a hydrogen sulfide resistant anhydrogenated sealing material. The addition of calcium chloride to the mixture of less than 4.01 wt.% Reduces the formation of gypsum, and an increase in the addition of more than 5.13 wt.% Reduces the setting time of the cement slurry.

Gypsum-magnesia grouting mortar as a component for the formation of magnesia stone contains magnesium chloride in an amount of 8.12-11.17 mass%. The addition of magnesium chloride to the mixture allows, when converting it to magnesium sulfate, together with magnesium oxide to obtain high-strength hydrogen sulfide-resistant stone. The addition of magnesium chloride to the mixture of less than 8.12 wt.% Reduces the strength of the stone, and an increase in the addition of more than 11.17 wt.% Leads to the formation of cracks in the stone.

Gypsum-magnesia cement slurry as a chloride salt converter contains aluminum sulfate in an amount of 29.89-23.96 wt.%. The addition of aluminum sulfate to the mixture allows the conversion of chloride salts to sulfate compounds during the chemical reaction. The addition of aluminum sulfate to the mixture of less than 29.89 wt.% Reduces the formation of gypsum, and an increase in the addition of more than 23.96 wt.% Deoxidizes the solution, which leads to a thickening of the grouting composition.

Gypsum-magnesia grouting mortar as an additional binder contains magnesium oxide (caustic magnesite) in an amount of 1.82-2.33 wt.%. The addition of magnesium oxide to the mixture improves the strength of the formed stone. The addition of magnesium oxide to the mixture of less than 1.82 wt.% Reduces the strength of the stone, and an increase in the addition of more than 2.33 wt.% Increases the possibility of cracking of the stone.

Gypsum-magnesia grouting mortar as a structure-forming agent contains finely dispersed binder “Microdur” - 9.34-29.18 wt.%. The Mikrodur additive in the mixture of less than 9.34 wt.% Does not allow to obtain a durable stone, and an increase in the additive of more than 29.18 wt.% Reduces its pumpability.

The binder “Mikrodur” is produced by air separation of dust generated by grinding cement clinker, the technology of its manufacture was developed and mastered by the specialists of the company “INTRA - BAVGmbH” together with the specialists of the concern “Dyckerhoff” and is protected by the European patent. The diameter of the Mikrodur grains is 6-10 times or more smaller than Portland cement particles. Due to the small particle size (grain diameter ≤ 2-6 μm), high specific surface area (20 000-25 000 cm ² / g) and technologically selected particle size distribution, Mikrodur solutions have a fluidity comparable to that of water, even with a minimum amount of liquid mixing, which allows the suspension "Mikrodur" to penetrate deeply into low permeable rock. The use of a finely dispersed binder “Microdur” allows to bind mixing water to a greater extent and to densify the structure of the stone and provide its increased fluid resistance and durability. This is due to the fact that a finely dispersed binder is able to bind water many times more, since the water-solid ratio can reach 3.0-5.0 with a specific surface area of 20,000-25,000 cm ² / g versus 0.3-0.5 conventional grouting cements having a specific surface area of 2500-3500 cm ² / g.

In field conditions, gypsum-magnesia grouting mortar is prepared in the following way.

The required amount of water is collected in an ASM-25 or USO-20 type averaging machine, in which the calculated amount of S-3 superplasticizer and NTF moderator are dissolved. Then, with constant stirring, magnesium chloride (bischofite), calcium chloride, barium chloride, aluminum sulfate (alumina sulfate), magnesium oxide are added to this averaging tank, and then a binder - Microdur - is added using cement carriers or mixing machines to the required density of the cement slurry . Then the solution is pumped into the well.

The basic properties of mortar and stone are determined in the laboratory in accordance with GOST 1581-96 “Cement grouting” and GOST 26798.1-96 “Test methods”.

The density, spreadability, water separation of the solution is determined at 25 ° C and atmospheric pressure. For moderate temperatures, the thickening of the solution is determined at 75 ° C and atmospheric pressure. For the conditions of the automatic air flow at temperatures up to 90 ° C.

Spreadability is determined by the cone of AzNII, density - by a pycnometer, water separation - in a graduated cylinder, thickening time - on ZM-1002 and KTs-3 consistometers. The compressive strength of the cement stone is on the CHANDLER test bench (Model 4207D), gas permeability is on the GFS-830-SS instrument - CHANDLER.

When conducting laboratory tests were used:

- tap water;

- high water consumption, finely ground binder (Mikrodur 261R-X);

- superplasticizer C-3;

- nitrilotrimethylene phosphonic acid - NTP;

- calcium chloride:

- barium chloride;

- magnesium chloride (bischofite);

- aluminum sulfate (alumina sulfate);

- Magnesium oxide (caustic magnesite).

Example.

To prepare a gypsum-magnesia cement slurry of increased density (composition 6, Table 1), bischofite brine with a density of 1.32 g / cm ³ weighing 239 g (9.41 wt.%) Is sequentially mixed, 680 g (27.13 wt.%) Are added. ) water, 5 g (0.24 wt.%) NTF, 10 g (0.4 wt.%) S-3 superplasticizer, 110 g (4.38 wt.%) calcium chloride, 207 g (8.27 wt.) %.) of barium chloride, 640 g (25.94 wt.%) aluminum sulfate, 50 g (1.99 wt.%) magnesium oxide and 600 g (22.56 wt.%) Mikrodur. The composition is stirred for 3 minutes, after which the density, flowability, pumpability at a temperature of 25 ° C and atmospheric pressure are determined.

When re-cooking, pour molds for the formation of samples when testing for strength after 72 hours of hardening, when testing for permeability after 5 days of hardening.

Gypsum-magnesia grouting mortar of the proposed composition with the content of these components in the claimed range has a high density (1.64 g / cm ³ ), a normative value of spreadability (200 mm) (see composition 6 table 1), pumpability 4-00 hours and strength compression of 6.6 MPa after 3 days of hardening at a temperature of 25 ° C, permeability less than 0.005 μm ² after 5 days.

The application of the proposed gypsum-magnesia grouting solution will allow:

- to expand the technological capabilities of the grouting mortar and the scope of its application due to the increased density, providing the necessary pressure similar to that of the mountain, and the spreadability of the mixture, providing increased mobility of the mixture in the initial period;

- to increase the efficiency and reliability of the insulation and repair work due to the increased fluid resistance, water, salt, hydrogen sulfide resistance and durability of the resulting cement stone.

The economic effect of the use of the inventive gypsum-magnesia grouting mortar will be determined by a decrease in the overhaul period and an increase in the life of the grouting mixture.

Claims (1)

Gypsum-magnesia cement slurry, including Microdur, calcium chloride, aluminum sulfate, NTF, water, characterized in that it additionally contains barium chloride, magnesium chloride, magnesium oxide and C-3 superplasticizer in the following ratio of ingredients, wt.%:
Calcium Chloride CaCl ₂ 4.01-5.13 Barium Chloride BaCl ₂ 7.56-9.68 Magnesium Chloride MgCl ₂ · 6H ₂ O (density 1.32 g / cm ³ ) 8.12-11.17 Aluminum sulphate Al ₂ (SO ₄ ) ₃ · 18H ₂ O (alumina sulfate) 23.96-29.89 Magnesium Oxide MgO (caustic magnesite) 1.82-2.33 Water 24.81-31.77 Microdur 9.34-29.18 Superplasticizer S-3 0.36-0.46 NTF 0.18-0.23