RU2474603C2 - High-structure grouting mixture - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: high-structure grouting mixture contains plugging Portland cement, gel powder -bentonite, alumina sulphate, hollow glass microspheres, high-water-demanding fine binding agent - Mikrodur or INTRATSEM and water at the following ratios of components to plugging Portland cement, wt %: plugging Portland cement 100, gel powder - bentonite 25.0-50.0, alumina sulphate 0.5-6.0, light-weight additive 5.0-10.0, high-water-demanding fine binding agent 5.0-10.0, and water 195-340.

EFFECT: reduction of density of grouting mixture at simultaneous increase in its mobility during the initial period and improvement of adhesive bond of a stone to mine rock.

1 ex, 2 tbl

Description

The invention relates to the drilling of oil, gas and water wells, in particular, to grouting mixtures designed to isolate zones of intense (complete) absorption.

For the successful isolation of zones of intense absorption, the correct selection of indicators of the structural and mechanical properties of grouting mixtures in static and dynamic conditions is of paramount importance. Therefore, it is important that from the moment the cement slurry enters the channels of the absorbing formation, it has the necessary specified values of plastic strength, shear stress, and density.

A well-known grouting mortar, including a binder, which facilitates the addition and water (see the description of the USSR copyright certificate No. 1640367 IPC Е21В 33/138, publ. 07.04.1991, bulletin No. 13).

Known cement slurry is intended for cementing wells in conditions of abnormally low reservoir pressure.

To increase the strength of the cement stone, while maintaining the cement paste, the well-known cement slurry additionally contains the NKNS-1 “40-03” superplasticizer and “water repellent” as a cementing cement slurry Portland cement, and as a lightening additive hollow glass microspheres.

A disadvantage of the well-known cement slurry is low penetrating and insulating ability of permeable formations.

Known grouting paste for isolating the absorption zone, containing a binder, polymer additive and a mixing fluid in the form of an aqueous solution of calcium chloride (see "The effectiveness of grouting pastes to eliminate absorption zones. Ser. Burenie, M., VNIIOENG, 1974, p. 43 )

As a binder, the well-known cement paste contains cement, and as a polymer additive, polyacrylamide.

The well-known cement paste has a high density and low structural and mechanical properties, which does not ensure its effectiveness in isolating zones of intense absorption, which is its main disadvantage.

A well-known grouting mixture consisting of a binder, a polymer additive and a mixing fluid in the form of an aqueous solution of calcium chloride (see description to USSR copyright certificate No. 692982, IPC ЕВВ 33/138, publ. 25.10.79, bulletin No. 39).

Known cement mixture as a binder contains gypsum-alumina cement, and as a polymer additive - gypsum.

The disadvantages of the well-known cement mixture are:

- instability of the basic structural and mechanical properties due to the process of preparation and injection;

- high density and low strength of the stone.

A known mixture for isolating absorbing layers in a well, consisting of cement, clay powder (bentonite) (see description of USSR author's certificate No. 212914, IPC E21B, publ. 12.03.1968, bulletin No. 10). As a known cement mixture contains gypsum-alumina cement, and as an activator of structure formation - two-water gypsum.

The disadvantages of the mixture for isolating the absorbing formations are the high density of the mortar, low strength and stability of cement stone.

A well-known grouting mixture for isolating absorbing formations, consisting of cement, clay powder, alumina sulfate and water (see description to USSR author's certificate No. 480827, IPC ЕВВ 33/138, publ. 15.02.78, bulletin No. 6).

As cement, the known mixture contains cement cement.

The disadvantages of the specified cement mixture is:

- high density;

- low adhesive adhesion of cement stone with rock;

- insufficient mobility in the initial period.

Closest to the proposed compositional solution is grouting mixture for isolation of absorbing formations, including grouting cement, clay powder (bentonite), alumina sulfate and water (see description to USSR author's certificate No. 325346, IPC Е21В 33/138, publ. 07.01.1972 Bulletin No. 3).

The disadvantages of the well-known cement mixture are:

- high density;

- low adhesive adhesion of cement stone with rock;

- insufficient mobility in the initial period.

The technical task of the invention is to expand the scope by reducing the density of the grouting mixture while increasing the mobility of the mixture in the initial period and increasing the adhesion of the stone to the rock.

The technical result is aimed at creating a lightweight cement mixture with a density of 1.20-1.30 g / cm ³ with certain structural, mechanical and plugging properties of the solution, strength and adhesion characteristics of the stone, allowing for effective isolation of highly permeable formations with intense (catastrophic) mud absorption .

The technical problem is solved in that a highly structured grouting mixture contains grouting Portland cement, clay powder (bentonite), alumina sulfate and water, while it additionally contains a lightening additive - hollow glass microspheres and high-demanding finely ground binder “Microdur” or INTRACEM cement with the following ratio weight parts:

cement Portland cement one hundred clay powder (bentonite) 25.0-50.0 alumina sulfate 0.5-6.0 lightweight supplement - hollow glass microspheres 5.0-10.0 high water fine binder Microdur or Intracem 5.0-10.0 water 195-340

The essence of the invention lies in the fact that in a highly structured grouting mixture, a lightening additive is additionally used - hollow glass microspheres and high-consumption thin-milled binder Mikrodur or Intrats, which improves the quality of insulation of absorbing layers by reducing the density of the grouting mixture, ensuring the necessary mobility of the mixture in the initial period insulation work, increasing the adhesion adhesion of cement stone with walls absorbing to caught under ambient and elevated temperatures.

Hollow glass microspheres in the proposed highly structured grouting mixture are used as a lightening additive.

Hollow glass microspheres are a light, free-flowing powder of uniform white color, consisting of thin-walled gas-filled individual hollow spherical particles filled with carbon dioxide or nitrogen, preferably ranging in size from 10 to 60 microns. Hollow glass microspheres are made from sodium borosilicate glass by the Novgorod Glass Fiber Plant and JSC NPO Glass Fiber.

Glass microspheres are characterized not only by low density, but also by high specific compressive strength. Hollow glass microspheres have a large specific surface area and particle sizes smaller than cement particle sizes. Therefore, they more actively adsorb the mixing fluid at the initial stage of hydration, uniformly distributed in the volume of the solution (stone), forming a composite material.

In addition to reducing the density and increasing the sealing properties of the grouting mixture, the addition of hollow glass microspheres provides a high quality of absorption isolation by increasing the adhesion of the stone to the walls of the absorption channels, which occurs in prestressed stone when the pressure changes during the insulation work.

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

In the proposed highly structured 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 seconds.

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 Intratsom allows you to more fully bind water and seal 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.

Under field conditions, a highly structured grouting mortar is prepared in two ways.

In the first method, a dry cement slurry is first prepared by mixing Portland cement, clay powder (bentonite), Mikrodur and hollow glass microspheres using, in a production base, mixing devices and silo containers, and in a drilling environment using cement trucks and cement mixing machines. Then the prepared dry cement mixture is shut in the usual way on a pre-prepared solution of alumina sulfate and pumped into the well.

According to the second method, in the presence of averaging machines such as ASM-25 or USO-20, the grouting mixture is prepared in the following way. First, the required amount of water is collected in the averaging tank, in which the calculated amount of alumina sulfate is dissolved. Then, with constant stirring, the calculated amount of Portland cement, clay powder (bentonite), Microdur and hollow glass microspheres are added to this averaging tank using cement trucks or mixing machines. The grout mixture is adjusted to the required density and then pumped into the well.

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 25 ° C and atmospheric pressure. For conditions of moderate temperatures, tests are carried out at 75 ° C and atmospheric pressure. For the conditions of automatic pressure control at temperature conditions up to 90-100 ° С and pressure 40-60 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 strengths - on a test bench (Model 4207D - CHANDLER), gas permeability - on a GFS- device 830-SS-CHANDLER.

When conducting laboratory tests were used:

- tap water;

- Portland cement grouting PCT I-50 in accordance with GOST 1581-96;

- clay powder (bentonite) TU -39-0147001-105-93;

- Highly water-consuming, finely ground binder (Mikrodur -261R-X or Intracem);

- lightening additive - hollow glass microspheres according to TU 6-48-108-94;

- sulfate alumina (aluminum sulfate) according to GOST 12966-85.

Example.

To carry out the tests, a cement slurry is first prepared, mixing with dry mixing a highly structured dry cement slurry consisting of 100 g of PCT Portland cement I-50, 25 g of clay powder (bentonite), 5 g of PSMS and 5 g of Microdur -261R-X or INTRACEM, on the solution alumina sulfate taken in an amount of 0.5 g and dissolved in 195 cm ^{3 of} water. After stirring for 3 minutes, the flowability and density of the solution are measured. Then, pouring the grouting mortar into the molds, determine the plastic strength of the mortar and prepare samples to determine the strength of the grouting stone in compression and adhesive adhesion.

The claimed and known prototype compositions with various component contents were investigated, and the research results are placed in a table.

As a result of the analysis of the table, it was noted that the composition of the highly structured mixture according to the prototype with satisfactory compressive strength of the stone has a high density of the solution (1.610-1.645 g / cm ³ ), low mobility (spreadability) of 100-140 mm, which limits the time of delivery of the mixture to the required depth , and low adhesive adhesion of the stone (formulations 19-20).

Highly structured cement mixture of the proposed composition with the content of these components in the claimed range has a reduced density (1,188-1,295 g / cm ³ ), increased values of spreadability (180-225 mm) and adhesive adhesion of the stone (see composition 1-10 table 1, table 2 ) The adhesive adhesion of the stone of the claimed compositions is more than 3 times higher than the adhesion of the composition according to the prototype, and the initial values of the spreadability and plastic strength allow us to provide the necessary delivery time of the highly structured mixture to a considerable depth.

It was found that the optimal content of hollow glass microspheres is 5-10 wt.% By weight of cement. With an increase in the content of hollow glass microspheres of more than 10 wt.%, It increases the rate of formation of the coagulation structure, which reduces the pumpability and reduces the strength of the stone (see composition 6 table 1, table 2). The addition of microspheres of less than 5 wt.% Leads to a decrease in the adhesive adhesion of the stone and an increase in the density of the solution (see composition 15 table 1, table 2).

The content of Mikrodur or INTRACEM is optimal in the range of 5-10 wt.%. The addition of more than 10 wt.% Mikrodur or Intratsom reduces the spreadability and pumpability of the grouting mixture (see composition 18). With the addition of less than 5 wt.% Mikrodur or Intrats decreases the strength characteristics of the stone for compression and adhesion adhesion (see composition 17 table 1, table 2).

The optimal content of the main structure-forming components in the inventive grouting mixture is clay powder (bentonite) from 25 to 50 wt.% And alumina sulfate from 0.5 to 6 wt.%. In this case, the addition of clay powder (bentonite) of less than 25 wt.% Significantly slows down the rate of set and reduces the plastic strength of the mixture (see composition 11 table 1, table 2), and an increase in the addition of more than 50 wt.% Leads to a decrease in the strength and adhesion of cement stone (see composition 13 table 1, table 2). The content of alumina sulfate is more than 7 wt.% - the mixture has increased plastic strength due to a sharp increase in the coagulation structure and the inability to deliver it to the absorption zone (see composition 14 table 1, table 2). When the content of alumina sulfate is less than 0.5 wt.%, The necessary coagulation structure and plastic strength of the cement mixture are not formed (see composition 12 table 1, table 2).

The application of the proposed highly structured grouting mixture will allow:

- expand the scope and improve the reliability of plugging the insulation zones of absorbing formations;

- reduce the density of the cement mixture while increasing the mobility of the mixture in the initial period;

- increase the adhesion adhesion of the stone to the rock.

- reduce time and material consumption for the elimination of the absorption of drilling fluid and process fluids.

The use of the inventive highly structured grouting mixture will reduce the time and material consumption to eliminate the absorption of drilling fluid and process fluids.

Claims (1)

Highly structured grouting mixture containing grouting Portland cement, clay powder - bentonite, alumina sulfate and water, characterized in that it additionally contains hollow glass microspheres and high-consumption fine-ground binder "Microdur" or INTRACEM with the following ratios of components to grouting port.
cement Portland cement one hundred clay powder - bentonite 25.0-50.0 alumina sulfate 0.5-6.0 hollow glass microspheres 5.0-10.0 high water fine binder Mikrodur or INTRACEM 5.0-10.0 water 195-340