RU2507380C1 - Low-density grouting mortar - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: low-density grouting mortar contains astringent, light filler, super plasticiser C-3, nitrile trimethyl phosphonic acid - NTF and water. Said binder represents high-water-absorption finely ground binder with specific surface of 20000-25000 cm²/g - "Microdur" or INTRATSEM while light filler is composed of hollow glass microspheres. Said components are present at the following ratio, wt %: high-water-absorption finely ground binder - 100, hollow glass microspheres - 10-100, NTF - 0.07-0.25, super plasticiser C-3 - 0.2-1.3, water - 150-320.

EFFECT: expanded applications, higher penetration ability, higher adhesion of stone with rock.

2 tbl, 1 ex

Description

The invention relates to the construction of oil, gas and water wells, in particular to grouting mixtures intended for fastening casing strings, uncoupling aquifers, oil and gas strata and isolating zones of intense (complete) absorption.

For successful separation of aquifers and oil and gas bearing strata during casing fastening, in developed strata with anomalously low reservoir pressure (ANPD), isolation of intense absorption zones, the correct selection of the necessary density of grouting mixtures and their structural and mechanical properties under static and dynamic conditions is of paramount importance . Therefore, it is important that the grouting mixture from the moment of penetration into the channels of the permeable and absorbing layer possesses the required set values of density, plastic strength, shear stress.

Known lightweight grouting mortars, including binder, additives and water (see. "Reference Guide to grouting materials", V. S. Danyushevsky and others - M .: "Nedra", 1987, pp. 102-107), intended for cementing wells at low reservoir pressures. By combining the amount of additive (bentonite, diatomite, filterroperlite, flask, etc.) with respect to the binder, its density and water-solid ratio, cement slurries with a density of 1.60 to 1.35 g / cm ³ with a satisfactory strength of cement stone can be obtained.

A disadvantage of the known lightweight solutions is:

- the impossibility of reducing their density without loss of mechanical strength;

- low penetrating and insulating properties in permeable formations.

Grouted slurries with lower density are required at the fields in the developed reservoirs, which can be obtained with additives having air or gas cavities (expanded perlite sand, expanded vermiculite sand, expanded glass, hollow microspheres, etc.).

Known lightweight grouting material according to patent RU No. 2256774, used as a building material, including for cementing oil, gas and geothermal wells, having a density of 1.1-1.4 g / cm ³ , consisting of a mixture of one of the grades of known cement and a lightweight filler, which consists of a composition containing hollow aluminosilicate microspheres, kaolin and surface-active aluminum hydroxide, Portland cement of the PTs 1-50 or PTs 1-100 brands is used as one of the brands of known cement. Hollow aluminosilicate microspheres are obtained by hydroseparating an aqueous suspension of ash in an ash pond, which have a size of 40-100 microns and a bulk density of 0.3-0.5 g / cm ³ .

The disadvantages of this lightweight cementing material is:

- the impossibility of preparing a solution with a density of less than 1.1 g / cm ³ ;

- very low strength and stability of cement stone.

Closest to the proposed solution is cement grout according to Auth. USSR No. 1640367, including binder - grouting Portland cement (PCT), gas-filled glass microspheres, treated with aminopropyltriethoxysilane (APSMS), NKNS-1 "40-03" superplasticizer based on the product of the condensation of sulfonated aromatic hydrocarbons from gas oil hydrophilic condensation and hydrolysis of oil and hydrogen sulfide HMF - an aqueous suspension of microbial fat saponified with sodium hydroxide and calcified with calcium chloride and water, in the following ratio of ingredients, wt.%: PCT - 44.1-69.3, APS C - 3,5-13,2, superplasticizer NKNS-1 "40-03" - 0.3-0.5, hydrophobing GMZH - 0.4-0.7, water-26,0-41,9.

A disadvantage of the well-known grouting mortar is:

- the impossibility of its preparation with a density below 1.0 g / cm ³ , since cement cement has a relatively small specific surface area of 2500-3500 cm ² / g and with the addition of excess water and microspheres, cement is not formed from the cement slurry or its mechanical strength sharply decreases;

- low penetration.

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

The technical result is aimed at creating a lightweight cement slurry with a density of up to 0.75 g / cm ³ with certain structural, mechanical and plugging properties of the mortar, strength and adhesion characteristics of the stone, which allow for efficient separation of aquifers and oil strata, isolation of highly permeable formations with intense (catastrophic) mud absorption, including in depleted fields with APP.

The technical problem is solved in that the cement slurry of low density contains an astringent and lightweight filler, C-3 superplasticizer, nitrilotrimethylenephosphonic acid - NTF, while it contains a highly-demanding, finely ground binder with a specific surface area of 20,000-25,000 cm ² / g "Microdur" or INTRACEM, and as a lightweight filler - hollow glass microspheres (PSMS) with the following ratios of components to cement Portland cement, parts by weight:

High water

fine binder

Mikrodur or INTRACEM 100

Hollow Glass Microspheres 10-100

Nitrilotrimethylene Phosphonic

acid - NTF 0.07-0.25

Superplasticizer S-3 0.2-1.3

Water 150-320

The essence of the invention lies in the fact that in a cement slurry of low density a lightweight filler is used - hollow glass microspheres and a highly water-consuming, finely ground binder with a specific surface area of 20,000-25,000 cm ² / g Mikrodur or INTRACEM, which improves the quality of fastening of casing strings and separation of water-gas-oil-bearing layers, isolation of absorbing layers by reducing the density of the cement mixture to the desired value, providing the necessary mobility and high penetration These mixtures in the initial period of fastening and insulation work, increase the adhesion strength of cement stone with the walls of the absorbing channels under normal and elevated temperatures.

Hollow glass microspheres in the proposed cement slurry of low density are used as a lightening additive and a lightweight filler.

Hollow glass microspheres are a light, loose powder of uniform white color, consisting of thin-walled gas-filled individual hollow spherical particles filled with carbon dioxide or nitrogen, with a size of mainly from 10 to 60 microns. Hollow glass microspheres are made from sodium borosilicate glass by the Novgorod Glass Fiber Plant, JSC NPO Stekloplastik and, unlike the finished ones used in the prototype, have a true density of 0.3-0.4 g / cm ³ versus 0.7-0.9 g / cm ³ .

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 grout, hollow glass microspheres provide high quality insulation of absorption by increasing the adhesion of the stone to the walls of the absorption channels, which occurs in prestressed stone when the pressure changes during insulation work.

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

In the proposed low-density grouting mortar, 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 Portland cement particles. Due to the small particle size (grain diameter ≤2-6 μm), high specific surface area (20000 -25000 cm ² / g) and technologically selected particle size distribution, Microdur solutions have a fluidity comparable to that 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 the small particle size (less than 4-5 microns), high specific surface area (> 10000 cm ² / g) and normalized particle size distribution and the introduction of special additives, “INTRACEM” forms stable aqueous dispersions with high penetration, which allows the “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 “Microdur” or “INTRACEM” allows to bind mixing water to a greater extent and to compact the structure of the stone and ensure its increased fluid resistance and durability. This is due to the fact that finely dispersed binders are able to bind water many times more, since the water-solid ratio of which can reach 3.0–5.0 with a specific surface 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.

The optimal content of hollow glass microspheres is 10-110 wt.% To the weight of the binder. With an increase in the content of hollow glass microspheres more than PO wt.%, The strength of the stone decreases. The addition of microspheres of less than 10 wt.% Leads to an increase in the density of the solution.

The optimal content of the main rheological components in the inventive cement slurry of low density is - NTF from 0.07 to 0.25 wt.% And superplasticizer C-3 from 0.2 to 1.3 wt.%. Moreover, the addition of NTF less than 0.07 wt.% Significantly reduces the rate of thickening, and an increase in the addition of more than 0.25 wt.% Slows down the setting process and reduces the strength of the stone in the initial period. The content of the C-3 superplasticizer of more than 1.3 wt.% Leads to a decrease in the stability of the solution and to its delamination, and when the content is less than 0.2 wt.%, The spreadability of the solution decreases, i.e. the solution becomes non-pumpable.

Under field conditions, cement slurry of low density is prepared in two ways.

In the first method, a dry cement mixture of binder and hollow glass microspheres is prepared using, in the conditions of the production base, mixing devices and silo containers. In a drilling environment, cement trucks and cement mixing machines are used to prepare the dry mix. After preparation, the dry cement mixture is shut in the usual way on a previously prepared solution with the addition of superplasticizer C-3 and NTF 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 C-3 superplasticizer and NTF moderator are dissolved. Then, with constant stirring, the calculated amount of hollow glass microspheres is added to this averaging tank, and then, using cement trucks or mixing machines, the binder is added 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, flowability, 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 AHP conditions at temperatures up to 90 ° C.

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

When conducting laboratory tests were used:

- tap water;

- Highly water-consuming, finely ground binder (Microdur 261R-X or INTRACEM);

- hollow glass microspheres (PSMS) according to TU 6-48-108-94;

- superplasticizer C-3;

- nitrilotrimethylene phosphonic acid - NTP.

Example

When conducting tests (see composition 14, table 1), a mixing liquid is first prepared with the addition of 0.8 g of S-3 superplasticizer, 0.17 g of NTF per 200 g of water. Then, with constant stirring, 50 g of PSMS and 100 g of Mikrodur - 261R-X are successively introduced. After mixing the solution for 3 minutes, its spreadability and density are measured and the grouting mortar is poured into the consistometer (without pressure) to determine thickening at 90 ° C. In addition, samples are formed under specified conditions to determine the compressive strength of the cement stone.

A cement slurry of low density of the proposed composition with the content of these components in the claimed range has a reduced density (0.88 g / cm ³ ), a normative value of spreadability (200 mm) (see composition 14 table 1), pumped time 2 hours 45 minutes and strength compression of 4.9 MPa after 2 days of hardening at a temperature of 90 ° C. The values of spreadability and pumpability allow us to ensure the delivery of cement slurry of low density to a considerable depth.

The use of the proposed cement slurry of low density will allow:

- expand the scope and improve the reliability of the isolation of the absorbing formations in the conditions of the oil and gas production in depleted fields;

- reduce the density of the cement slurry below the density of the mixing fluid;

- increase the strength of the adhesive adhesion of the stone with the rock;

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

The use of the inventive cement slurry of low density will reduce the time and material consumption for work associated with the separation of aquifers and oil strata and the elimination of absorption of the drilling fluid.

Claims (1)

Low density cement slurry containing a binder, a lightweight filler, C-3 superplasticizer, nitrilotrimethylene phosphonic acid - NTF and water, characterized in that it contains a high-demanding, finely ground binder with a specific surface of 20,000-25,000 cm ² / g - "Microcure" or INTRA as a binder , and as a lightweight filler - hollow glass microspheres with the following ratios of components, parts by weight:
High water fine binder Mikrodur or INTRACEM one hundred Hollow Glass Microspheres 10-100 Nitrilotrimethylene Phosphonic acid - NTF 0.07-0.25 Superplasticizer S-3 0.2-1.3 Water 150-320