RU2802474C1 - Gypsum cement grouting solution - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry, in particular to grouting solutions designed to create insulating screens for the elimination of absorption in the intervals of weakly cemented and loose rocks with abnormally low reservoir pressure and low hydraulic fracturing gradient (less than 0.0120 MPa/m). Gypsum cement grouting solution contains, wt.%: high-strength gypsum of the GVVS brand-19 29,74-35,69; micro cement 1.78-8.92; Granulight GS glass microspheres 2.97-10.11; Granulite alumosilicate microspheres-2500 7,73-17,85 ; micro-silica condensed MK-85 2,97-5,95 ; plasticizer of the Easy Flow PC brand 0.01-0.09; sealing liquid - 40.44-40.47.

EFFECT: gypsum cement grouting solution with a density of 1100±60 kg / m³ is provided, characterized by high sedimentation stability and a short period of hydration of the solution.

1 cl, 1 tbl

Description

The invention relates to the oil and gas industry, in particular to cementing solutions intended for creating isolating screens when eliminating losses in intervals of weakly consolidated and loose rocks with abnormally low reservoir pressure and low hydraulic fracturing gradient (less than 0.0120 MPa/m).

A known raw material mixture for producing a lightweight cement slurry for fastening casing strings under conditions of normal and abnormally low reservoir pressures, as well as in intervals with a predominance of permafrost, contains, wt.%: Portland cement cement 38-53.5; hollow ceramic microspheres 10.7-22.8; complex additive “Murapor Combi 756” 0.114-0.16; mixing liquid - water or 2-8% solution of sodium chloride or calcium chloride - the rest [RU 2472835 C1, IPC C09K 8/467, publ. 01/20/2013].

The disadvantage of the known invention is the low sedimentation stability of the solution.

A lightweight cement slurry is known, used for cementing oil and gas wells complicated by the presence of formations with abnormally low reservoir pressures containing, wt.%: clinker - 50; gypsum - 2.5; tripoli - 35; baking dust from electric precipitators - 12.5; POHA - 1.3-1.5% over 100%, with a water-cement ratio of 1.3 [RU 2230883 C2, IPC E21B 33/138, publ. 06/20/2004]/

The disadvantage of the known invention is the relatively small tensile strength of the stone.

A well-known cement mixture related to the construction of wells and their overhaul, namely when fastening casing strings and creating fluid-resistant insulating tires in the range of chemogenic deposits, as well as to the process of exploitation of fields and abandonment of wells, contains, wt.%: semi-aqueous gypsum 50.00- 53.95; "Microdur-26RC"2.00-8.50; sodium chloride brine with a specific gravity of 1.18 g/cm ³ 41.42-44.00; NTF 0.05-0.08 [RU 2304606 C1, IPC C09K 8/487, publ. 20 08.2007].

The disadvantages of the known invention are the relative high density and minimal spreadability of the resulting cement slurry.

There is a known lightweight cement slurry used for cementing casing strings of gas, gas condensate or oil wells, complicated by the presence of weakly bound rocks prone to hydraulic fracturing, containing, wt.%: Portland cement cement 36.47-57.34, aluminosilicate hollow microspheres 6.47-17 .65, carboaluminate additive 1.18-2.67; gypsum 1.18-2.67; water or 4% solution of calcium chloride - the rest [RU 2151271 C1, IPC E21B 33/138, publ. 06/20/2000]. Lightweight cement mortar is characterized by expansion and optimal strength properties of the stone.

The disadvantage of the known invention is the long hydration period.

The closest is a cement mortar for cementing an oil well and similar wells, having a density in the range of 0.9-1.3 g/cm ³ , consisting of a solid fraction and a liquid fraction and having a density (volume ratio of the liquid fraction to the solid fraction) within 38-50%, with said solid fraction containing the following: 60-90 vol.% light particles having an average size in the range of 20-350 microns (µm); 10-30 vol.% microcement having an average particle diameter in the range of 0.5-5 microns; 0-20 vol.% Portland cement having particles with an average diameter in the range of 20-50 microns; and 0-30 vol.% gypsum [EA 003917 B1, IPC C04B 28/02, E21B 33/13, C04 B 28/08, publ. 10/30/2003]. The resulting stone from a well-known cement mortar has improved mechanical properties in comparison with foam cement mortars.

The disadvantage of cement mortar is the absence of stone in the material that provides water resistance.

The technical problem to be solved by the proposed invention is to improve the quality of work to eliminate losses in intervals caused by the presence of weakly consolidated and loose rocks with abnormally low reservoir pressure and low hydraulic fracturing gradient (less than 0.0120 MPa/m).

The technical result is the creation of a gypsum cement cement mortar with a density of 1100±60 kg/m ³ , characterized by a short period of hydration of the solution and sufficient strength of the stone to create an insulating screen.

The specified technical result is achieved by the fact that the gypsum cement cement mortar includes gypsum, microcement, light particles and a mixing liquid; what is new is that high-strength gypsum of the GVVS-19 brand is used, glass microspheres of the Granulight GS brand and aluminosilicate microspheres of the Granulight brand are used as light particles. 2500, and additionally the gypsum cement cement mortar contains condensed silica fume grade MK-85, plasticizer grade Easy Flow PC, and process water or 4% aqueous solutions of chloride salts are used as the mixing liquid, with the following ratio of the indicated components, wt.%:

high-strength gypsum GVVS-19 29.74-35.69 microcement 1.78-8.92 indicated glass microspheres 2.97-10.11 said aluminosilicate microspheres 7.73-17.85 condensed microsilica MK-85 2.97-5.95 specified plasticizer 0.01-0.09 mixing liquid - industrial water or 4% aqueous solutions of chloride salts 40.44-40.47

Achieving the specified technical result is ensured by a certain combination of components (quantitative and qualitative) in the inventive gypsum cement cement mortar and the set of necessary physical and chemical processes occurring during the formation of the stone.

The functional purpose of high-strength gypsum brand GVVS-19 in the composition of the proposed mixture is to accelerate the process of hydration of the solution.

Glass and aluminosilicate microspheres in the proposed mixture perform the function of facilitating the density of the solution. The presence of micronized cement ensures the process of crystallization of new formations and the production of durable cement stone.

The presence of amorphous microsilica in the mixture ensures stabilization of the rheological parameters of the solution and the water resistance of the stone.

The introduction of a plasticizer makes it possible to increase the spreadability of the prepared solution.

The proposed quantitative ratio of the components and subsequent reactions between them after mixing make it possible to obtain a lightweight cement slurry with a short period of hydration of the solution and sufficient stone strength. Thus, the potential use of this solution will solve the technical problem of improving the quality of work to eliminate losses in intervals caused by the presence of weakly consolidated and loose rocks with abnormally low reservoir pressure and low hydraulic fracturing gradient (less than 0.0120 MPa/m).

The preparation of the proposed gypsum cement cement mortar is carried out using the following components:

- high-strength gypsum brand GVVS-19 produced in accordance with GOST 125-2018 - high-strength separated gypsum binder;

- micronized cement (microcement) according to TU 5739-021-80338612-2014, which is intended for the construction of wells, strengthening soil masses, reinforced concrete and stone structures. Microcements include products with a particle size of less than 20 microns and a specific surface area of more than 650 m ² /kg. Microcement is made by finely grinding and classifying cement cement PCT IG-CC-1 GOST 1581 or Portland cement TsEM I 42.5 N GOST 31108 with the addition of sulfate-resistant additives;

- microspheres of the Granulite-2500 brand according to TU 5712-010-80338612-2008, manufactured by Granula LLC, are hollow microspheres, finely dispersed powder, consisting of hollow spherical particles of the following mineralogical composition: glass - 12-15%, mullite - 50- 53%, quartz - 32-38%. Color - white with a slight grayish or cream tint, light gray, gray, dark gray. Hardness on the Mohs scale - 6. Apparent density - 065-0.85 g/cm ³ . Designed for the production of cement cement mixtures, drilling fluids, fireproof, sound and heat insulating materials, as light fillers (lightening additives for obtaining systems with low density) in concrete, dry construction mixtures, cement mixtures. Microspheres are formed during the combustion of coal, released by separation by flotation and subsequent technological processing;

- Granulight GS glass microspheres according to TU 5759-039-80338612-2015, manufactured by Granula LLC, characteristic properties are low true density 0.35-0.39 g/cm ³ . The manufacturer does not disclose the basis of the product. The specified component is selected and used in the composition of the proposed cement slurry, based on previously obtained results of laboratory tests in the preparation of cement slurry compositions;

- condensed microsilica grade MK-85 according to TU 14-142-023-00186476-2020 - intended for use as a highly active mineral additive to concrete and cement, supplied in uncompacted form. Condensed microsilica is an ultradisperse material consisting of spherical particles, obtained during the purification of gases coming from furnaces during the production of silicon-containing alloys. The main component of the material is amorphous silicon dioxide. Condensed uncompacted microsilica is obtained by selecting material from bag filters of gas purification systems of furnaces that smelt silicon-containing alloys. Appearance - ultrafine gray powder;

- plasticizer brand Easy FLOW PC according to TU 2458-027-33217677-2017 is a mixture of polymers based on polycarboxylates, designed to reduce viscosity and improve pumpability of cement slurries, as well as to reduce hydrodynamic pressures when cementing casing strings. It is a white powder with a moisture content of no more than 10%,

- process water or 4% aqueous solutions of chloride salts are used as the mixing liquid, for example, a 4% sodium chloride solution or a 4% calcium chloride solution.

Technological properties of mortar and stone were determined in accordance with GOST 34532-2019 “Ground cements. Test methods".

Gypsum cement cement mortar was prepared in laboratory conditions as follows.

First, the dry components are mixed in specified ratios, and the resulting material is thoroughly mixed by hand for homogenization. Then the material is mixed with industrial water in a laboratory mixer SL-1 in accordance with GOST 34532-2019 and the technological properties of the resulting solution and the formed stone are determined.

Example. To prepare the proposed solution (table, composition 4), 35.69 wt.% of high-strength gypsum grade GVVS-19 is required; 2.97 wt.% microcement, 5.96 wt.% glass microspheres of the Granulight GS brand; 11.90 wt. % aluminosilicate microspheres of the Granulite-2500 brand, 2.97 wt.% condensed microsilica MK-85; 0.06 wt.% Easy Flow PC plasticizer, weighed dry components are mixed until a homogeneous mixture is obtained. Next, a cement slurry is prepared from the resulting cement mixture by mixing the mixture with 40.45 wt.% technical water. Mixing is carried out on a laboratory mixer SL-1. After mixing, the following parameters are determined (test conditions - temperature 22 ° C and pressure 0.1 MPa), density (kg/ ^m3 ), spreadability (mm), water separation (ml), thickening time (min) and timing setting (min) of the resulting solution. The remaining part of the solution is poured into beam molds to determine the tensile strength of the stone (MPa) during bending and compression and stored for 48 hours.

The prepared solution has a density of 1.15 g/cm ³ , spreadability 254 mm, water separation 0.0 ml, thickening time up to 30 Vs is 57 minutes, the beginning and end of setting of the solution is 72 and 82 minutes after mixing, the bending strength of the stone is 0.97 MPa and in compression 1.78 MPa.

Examples of preparation and testing of the remaining compositions given in the table are similar to those described above.

As can be seen from the presented table, the inventive gypsum cement cement mortar, including high-strength gypsum of the GVVS-19 brand, microcement, aluminosilicate microspheres of the Granulight-2500 brand, glass microspheres of the Granulight GS brand, condensed silica fume of the MK-85 brand, plasticizer of the Easy Flow PC brand, as a liquid mixing uses industrial water or 4% aqueous solutions of chloride salts, for example, a 4% CaCl ₂ solution or a 4% NaCl solution at the specified ratio of components is superior to known analogues, namely, it is characterized by high sedimentation resistance and a short period of hydration of the solution.

To identify distinctive features and the claimed technical result, the mass ratios of the components were changed (table, compositions 17-21). In the case of prohibitive ratios of the components of the proposed solution, the prepared solutions are characterized by unacceptable spreadability values, for example, less than 180 mm (table, composition 19), sedimentation instability, for example, more than 4 ml (table, composition 21) and an increased hydration period.

Thus, the inventive gypsum cement cement slurry improves the quality of work to eliminate losses in intervals caused by the presence of weakly cemented and loose rocks with abnormally low reservoir pressure and low hydraulic fracturing gradient (less than 0.0120 MPa/m).

Claims (2)

Gypsum cement grouting mortar, including gypsum, microcement, light particles and mixing liquid, characterized in that high-strength gypsum of the GVVS-19 brand is used, glass microspheres of the Granulight GS brand and aluminosilicate microspheres of the Granulight-2500 brand are used as light particles, and additionally gypsum cement grouting mortar contains condensed microsilica of the MK-85 brand, a plasticizer of the Easy Flow PC brand, and industrial water or 4% aqueous solutions of chloride salts are used as the mixing liquid, with the following ratio of the indicated components, wt.%: high-strength gypsum GVVS-19 29.74-35.69 microcement 1.78-8.92 indicated glass microspheres 2.97-10.11 said aluminosilicate microspheres 7.73-17.85 condensed microsilica MK-85 2.97-5.95 specified plasticizer 0.01-0.09 mixing liquid - industrial water or 4% aqueous solutions of chloride salts 40.44-40.47