RU2471844C1 - Informative grouting mortar (versions) - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: as per the first version, grouting mortar contains ingredients at the following ratio, wt %: fine ground cement - Mikrodur or INTRATSEM 100, boric acid 2-3, aluminium sulphate 3-7, superplasticising agent C-3 0.3-1, liquid for pre-mixing 50-150. As per the second version, informative grouting mortar contains ingredients at the following ratio, wt %: Mikrodur or INTRATSEM 100, sodium tetraborate 5-10, potassium carbonate 5-10, superplasticising agent C-3 0.3-1, liquid for pre-mixing 50-150.

EFFECT: creation of informative grouting mortar that can be effectively used in wide ranges of temperatures, pressures, including in headers with intergranular space of less than 30 mcm, as well as at availability of cracks and micro cracks with smaller dimensions; besides, providing indication of cement distribution during unrestricted period of time after casing string by means of pulsed neutron logging, as well as improvement of manufacturing capabilities of grouting mortar due to increase in flowability of mixture and time of its pumping.

6 cl, 2 ex, 1 tbl

Description

The invention relates to the oil and gas industry, in particular to informative grouting mixtures with informative properties about the quality of cementing, determining filling intervals and injectivity when injecting grouting mortar and distributing its volumes vertically behind the string during cementing of casing strings, operation, isolation of formation water, overhaul and well liquidation.

A well-known grouting mixture containing a binder, mixing fluid and indicator additive (see M. S. Makarov "Application of the indicator method for radon in cementing wells." VNIIOENG, NTS, ser. Oil and gas geology, geophysics and drilling ", issue 5, 1985 )

As a binder, the well-known grouting mixture contains cement, as a mixing liquid - water, and as an indicator additive - a radioactive gas isotope-radon in the form of an aqueous solution of radon with an activity of 1500 microns.

The well-known grouting mixture does not provide sufficient reliability of the information obtained in time about the location and distribution of grouting mortar across rock layers in the annulus due to the migration (ascent) of gaseous radioactive indicators up. The use of krypton-85 gas in the well-known grouting mixture as an indicator additive of the radioactive radionuclide narrows its scope due to the increased cost of the technology and the danger to human health.

A well-known cement slurry containing an indicator additive (see. "Practical guidance on the use of the indicator method for a long-term assessment of the tightness of the annulus", RD-05-10-03, Volgograd, 2003, LLC Lukoil-Nizhnevolzhskneft, LLC Lukoil- Volgograd NIPImorneft "). As an indicator additive in the well-known grouting mixture, a radioactive radionuclide of krypton-85 gas is used, having a half-life of 10.3 years.

The well-known grouting mixture does not provide sufficient reliability of the information obtained in time about the location and distribution of grouting mortar across rock layers in the annulus due to the migration (ascent) of gaseous radioactive indicators up. The use of krypton-85 gas in the well-known grouting mixture as an indicator additive of the radioactive radionuclide narrows its scope due to the increased cost of the technology and the danger to human health.

Closest to the claimed grouting mixture, adopted as a prototype, is grouting mortar containing a binder, mixing fluid, indicator additive (see description to USSR author's certificate No. 1065581, IPC ЕВВ 33/138, publ. 07.01.84, bull. No. one).

As a binder, the well-known cement mixture contains cement, as a mixing liquid - water, and as an indicator additive - sodium octoborate Na ₂ B ₈ O ₁₃ and additionally contains an alkaline accelerator - soda ash and caustic soda.

The disadvantages of the well-known cement mortar are:

- a narrow scope, due to the difficulties of organizing the process of preparing the mixture in the field due to the fact that sodium octoborate, hydrolyzed in the mixing fluid, has a strong inhibitory effect on cement hardening;

- low efficiency of grouting due to poor filterability of the cement-based mixture, especially in low-permeability reservoirs, micro-gaps and microcracks, due to the size of cement particles of 30-50 microns, which cannot penetrate smaller channels, cracks and microcracks.

To slow down the hardening of the cement mortar, an alkaline reagent-accelerator — calcined soda — is introduced into the mixing fluid. But the too narrow limits of the additive of this accelerator, which has a low solubility, below which it does not affect the acceleration of setting, and above which the solution becomes non-pumpable, create additional difficulties when mixing the composition and reduce the reliability and safety of cementing operations. These difficulties can be eliminated by adding an additional alkaline accelerator, such as caustic soda, to the grouting mortar. In general, the addition of two alkaline accelerators causes certain practical difficulties in the process of preparation, regulation of pumpability and injection of cement mortar. Moreover, the use of caustic soda requires the use of special chemical protective equipment. In addition, sodium octoborate is a common reagent.

The technical task of the invention is to reduce the risk to human health, expand the scope and increase the efficiency of grouting by improving the technological capabilities of the grouting mixture (increasing the spreadability of the mixture, pumping time) and simplifying its preparation in field conditions, as well as the use of grouting mixture allows to determine its distribution in annular space and in rock.

The technical result is aimed at creating an informative grouting mixture with one accelerator and one widespread boron-containing reagent, which can be effectively used in wide ranges of temperatures, pressures, including in collectors with intergranular space less than 30 microns, as well as in the presence of cracks and microcracks with less dimensions, in addition, for an unlimited time to indicate the distribution of cement behind the casing using neutron pulsed logging.

The technical problem in the first embodiment is solved by the fact that the informative grouting mixture contains a binder, a mixing fluid, an indicator additive, while it additionally contains a technological properties regulator - S-3 superplasticizer and an accelerator - sulphate of alumina, and Microdur or INTRACEM as a binder - finely ground cement and as an indicator additive - boric acid, with the following ratios of ingredients to the weight of the binder, parts by weight:

fine cement Microdur or INTRACEM one hundred boric acid 2-3 alumina sulfate 3-7 superplasticizer C-3 0.3-1 mixing fluid 50-150

The technical problem according to the second option is solved in that the informative grouting mixture contains a binder, a mixing fluid, an indicator additive, while it additionally contains a technological properties regulator - S-3 superplasticizer, an accelerator - potassium carbonate, and as a binder - finely ground cement Microdur or INTRACEM , as an indicator additive - sodium tetraborate, with the following ratios of ingredients to the weight of the binder, parts by weight:

fine cement Microdur or INTRACEM one hundred sodium tetraborate 5-10 potassium carbonate 5-10 superplasticizer C-3 0.3-1 mixing fluid 50-150

As a mixing liquid, it contains water or a brine of sodium chloride, or calcium chloride, or calcium bromide, or zinc bromide.

The essence of the invention lies in the fact that, according to the first embodiment, the informative grouting mixture contains boric acid and additionally alumina sulfate and C-3 superplasticizer as an indicator, according to the second option, sodium tetraborate and additionally potassium carbonate and C-3 superplasticizer, and as a structurant (cement) use a finely dispersed binder Mikrodur or INTRACEM. In the proposed informative grouting mixture, the introduction of boron-containing substances allows for an unlimited time using neutron pulsed logging to indicate the distribution of cement behind the casing.

In natural rocks, the boron content is insignificant and amounts to thousandths of a percent, while boric acid in its composition contains 17.5% boron, and sodium tetraborate (borax Na ₂ B ₄ O ₇ · 10H ₂ O) contains 11.5% boron, which to the total mass of cement slurry is about 0.3-1%. This significant difference in boron content allows boric acid or sodium tetraborate to be an indicator of the location of the solution containing it.

Due to the lack of intrinsic gamma radiation, as in the well-known radioactive indicator isotopes, boric acid and sodium tetraborate do not require special precautions.

Of the known finely ground binders, the most effective are Microdur or INTRACEM, obtained on the basis of Portland cement.

In the proposed informative grouting mixture, highly finely ground cements, for example, Mikrodur or INTRACEM, are used as a highly demanding finely dispersed binder. 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 the particles of the cement clinker itself. Due to the small particle size (grain diameter ≤2-6 μm), high specific surface (2000-2500 m ² / kg) and smoothly selected particle size distribution, Mikrodur solutions have a fluidity comparable to the fluidity of water, even with a minimum amount of mixing liquid, which allows the suspension "Mikrodur" to penetrate deeply into low permeable rock. The expiration time (conditional viscosity) of a suspension under the age of 3 hours ranges from 28 to 30 s.

The manufacturing technology of specially ground cement "INTRACEM", which is close in its technological parameters to "Mikrodur", was developed by the Russian Chemical and Technical University named after D.I. Mendeleev. Due to its small particle size (less than 4.5 microns), high specific surface area (1000 m ² / kg) and normalized particle size distribution and the introduction of special additives, INTRACEM forms stable aqueous dispersions with high penetration, which allows INTRACEM solutions to penetrate into pores and cracks less than 0.1 mm in size, reducing the open porosity of materials by 2-15 times and increasing their mechanical strength.

In contrast to the prototype, the use of a finely dispersed binder Mikrodur or INTRACEM allows to more fully bind water and tighten the structure of the stone and thereby ensure its increased fluid resistance and durability. This is also due to the fact that finely dispersed binders are able to bind water many times more, since their water-solid ratio can reach 3.0–5.0 with a specific surface of 20,000–25,000 cm ³ / g versus 0.3–0.5 conventional grouting cements having a specific surface area of 3000-3500 cm ³ / g.

As the mixing fluid of the proposed informative grouting mixture, water or a brine of sodium chloride, or calcium chloride, or calcium bromide, or a mixture thereof in an amount of 50-150 parts by weight are used. density from 1.0 to 1.7 g / cm ³ . When the content of the mixing liquid is less than 50 parts by weight cement slurry becomes non-pumpable, with more than 150 parts by weight the solution has some sedimentation sediment. In the intervals of saline deposits and rape horizons, salted grouting mortar is used, prepared on brines chemically compatible with the rock, with the possibility of eliminating metabolic processes leading to the destruction of the grouting stone. If there is fresh or weakly mineralized water in the rock section, mixing liquids with a density of 1.0-1.06 g / cm ³ , mineralized and highly mineralized 1.06-1.20 g / cm ^{3 are used} , and in the presence of formations with an abnormally high reservoir pressure up to 1.7 g / cm ³ . This avoids the penetration of formation fluids into the structure of the stone at the stage of hardening and the formation of filtration channels and thereby prevents annular pressure and interstratal flows, while the stone has low gas permeability, the absence of cracks and channels and a sufficient density that provides the necessary back pressure on the strata and bore walls wells.

Option 1

Informative tampon mixture as an informative material contains boric acid (H ₃ BO ₃₎ in an amount of 2-3 parts by weight The addition of boric acid to the mixture is less than 2 parts by weight. weakly reacts to the time of neutron deceleration, and the increase in the additive is more than 3 parts by weight does not give a significant increase in the indications of neutron deceleration.

An informative grouting mixture as a setting accelerator contains alumina sulfate (aluminum sulfate Al ₂ (SO ₄ ) ₃ · 18H ₂ O) in an amount of 3-7 parts by weight The addition of alumina sulfate to the mixture is less than 3 parts by weight. increases the pumpability time of grouting mortar to 1 day, and the increase in additives is more than 7 parts by weight reduces pumping time to values insufficient for carrying out technological operations with grouting mortar.

An informative grouting mixture as a regulator of technological properties contains superplasticizer C-3 in an amount of 0.3-1. The addition of superplasticizer S-3 to a mixture of less than 0.3 parts by weight does not allow to reduce the viscosity of the cement slurry to the specified parameters, and the increase in additives is more than 1 weight.h. leads to a dilution of the grouting mortar and some delamination.

Option 2

An informative grouting mixture contains sodium tetraborate (borax Na ₂ B ₄ O ₇ · 10H ₂ O) in an amount of 5-10 parts by weight as an informative material. The addition of sodium tetraborate to a mixture of less than 5 parts by weight insufficient to detect the time of neutron deceleration, and the increase in the additive is more than 10 parts does not increase the information content of the solution.

An informative grouting mixture as a setting accelerator contains potassium carbonate (potash K ₂ CO ₃ ) in an amount of 5-10 parts by weight. The addition of potassium carbonate to a mixture of less than 5 parts by weight leads to an irrational increase in the pumpability and setting time, and an increase in the additive is more than 10 parts by weight reduces pumpability below the time required for technological operations.

An informative grouting mixture as a regulator of technological properties contains superplasticizer C-3 in an amount of 0.3-1. The addition of superplasticizer S-3 to a mixture of less than 0.3 parts by weight does not allow to reduce the viscosity of the cement slurry to the specified parameters, and the increase in additives is more than 1 weight.h. leads to a dilution of the grouting mortar and some delamination.

The preparation of an informative grouting mixture can be carried out in two ways:

- centrally in the workshop of dry cement compositions using well-known mixing chambers;

- directly at the well.

According to the first method, the prepared homogeneous mixture is fed into cement trucks or into bunkers of cement-mixing machines or packaged in sealed packages weighing 25-40 kg. Then the mixture by any means of transport is delivered to the well, where cement slurry is prepared from it.

According to the second method, an informative grouting solution is prepared in the well in the usual way using a clay mixer or ASM-25, USO-16 aggregate-mixing machines, into which components are successively introduced: water, a boron-containing substance, an accelerator reagent, a plasticizer reagent and a binder.

Determination of the basic properties of the mortar and stone is carried out in accordance with GOST 1581-96 "Cement grouting" and GOST 26798.1-96 "Test methods".

Determination of density, spreadability, water separation is carried out at 22 ° C and atmospheric pressure. For conditions of moderate temperatures, tests are carried out at 75-90 ° C and atmospheric pressure. For conditions of abnormally high reservoir pressures at temperatures up to 120 ° C and a pressure of 60 MPa. 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, compressive strength on a test bench 4207D - CHANDLER. Neutron deceleration was measured using a SGDT instrument.

The data on the tests are summarized in the table "Compositions and properties of grouting mixtures."

Example

To prepare an informative grouting mixture according to option 1 (see composition 9), with water with a volume of 1200 cm ³ , 30 g of boric acid, 70 g of alumina sulfate, 6 g of S-3 superplasticizer, 1000 g of Mikrodur are successively added to the water.

The composition is stirred for 3 minutes, after which the spreadability, density, and pumpability are determined. Then fill in the mold for testing samples for strength after 2 days of hardening.

For the composition of Embodiment 1 (see FIG. 9 composition) solution density of 1.46 g / ^cm3 flowability 23 cm, the bending strength of 2.0 MPa.

To measure neutron moderation, the prepared composition 9 is poured into a stand with an annular space of ⌀ 225 × 127 mm and a length of 1,500 m. A pulsed neutron gamma-ray logging device is placed inside the stand in a pipe with an inner diameter of 108 mm.

Measurements of neutron moderation showed a decrease in pulses per minute by 4-5 times compared with a sample prepared from pure Portland cement (see composition 1).

Example

To prepare an informative grouting mixture according to option 2 (see composition 13), 100 g of sodium tetraborate, 100 g of potassium carbonate, 10 g of C-3 superplasticizer, 1000 g of INTRACEM are successively added to water with a volume of 1200 cm ³ with constant stirring.

The composition is stirred for 3 minutes, after which the spreadability, density, and pumpability are determined. Pour molds for testing samples for strength after 2 days of hardening.

For the composition according to option 2 (see composition 13), the density of the solution is 1.46 g / cm ³ , the spreadability is 25 cm, the bending strength is 1.8 MPa.

To measure neutron moderation, the prepared composition 13 is poured into a stand with an annular space ⌀ 225 × 127 mm and a length of 1,500 m. A pulsed neutron gamma-ray logging device is placed inside the stand in a pipe with an inner diameter of 108 mm.

Measurements of neutron moderation showed a decrease in pulses per minute by 4-5 times compared with a sample prepared from pure Portland cement (see composition 1).

Using the proposed informative grouting mixture allows you to:

- expand the scope of application;

- increase the efficiency of grouting by improving the technological capabilities of grouting mixture, simplifying its preparation in field conditions and increased filtering ability in low-permeability reservoirs, micro-gaps and microcracks;

- provide the possibility of indicator monitoring for unlimited time;

- eliminate harmful effects on the environment and people.

The economic effect of the use of the claimed informative grouting mixture will be determined by increasing the efficiency of grouting and the possibility of indicator monitoring for unlimited time without attracting additional funds for the installation of indicator marks.

Claims (6)

1. An informative grouting mixture containing a binder, a mixing fluid, an indicator additive, characterized in that it additionally contains a regulator of technological properties - S-3 superplasticizer and an accelerator - alumina sulfate, as a binder - finely ground cement Microdur or INTRACEM and as an indicator additive boric acid in the following ratios of ingredients to the weight of the binder, parts by weight:
fine cement Microdur or INTRACEM one hundred boric acid 2-3 alumina sulfate 3-7 superplasticizer C-3 0.3-1 mixing fluid 50-150 2. The informative grouting mixture according to claim 1, characterized in that it contains water or brine as a mixing liquid. 3. The informative grouting mixture according to claim 2, characterized in that the brine contains an aqueous solution of sodium chloride, or calcium chloride, or calcium bromide, or zinc bromide. 4. An informative grouting mixture containing a binder, a mixing fluid, an indicator additive, characterized in that it additionally contains a regulator of technological properties - S-3 superplasticizer, accelerator - potassium carbonate, as a binder - fine-milled cement Microdur or INTRACEM and as an indicator additive - sodium tetraborate in the following ratios of ingredients to the weight of the binder, parts by weight:
fine cement Microdur or INTRACEM one hundred sodium tetraborate 5-10 potassium carbonate 5-10 superplasticizer C-3 0.3-1 mixing fluid 50-150 5. An informative grouting mixture according to claim 4, characterized in that it contains water or brine as a mixing liquid. 6. The informative grouting mixture according to claim 5, characterized in that the brine contains an aqueous solution of sodium chloride, or calcium chloride, or calcium bromide, or zinc bromide.