RU2561426C1 - Composition for creation of borehole filter - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: composition for creation of the borehole filter including the binder - Portland cement, fibrous filler - fibre, it also contains Microdur, high-soluble salt - carbonic potassium (potash) having inclusions of natural isotopes, retarder - boric acid with neutron-absorbing properties, tempered on saturated solution of the named salt, at the following ratio of ingredients, wt %: binder - Portland cement 43.79-45.77, microdur 4.57-7.31, fibrous filler - polymeric polypropylene fibre with a diameter 17-21 mcm and 12 mm long 0.23-0.37, high-soluble salt - carbonic potassium (potash) K₂CO₃ 2.29-2.92, retarder - boric acid H₃BO₃ 1.37-1.82, saturated solution of carbonic potassium K₂CO₃ γ = 1.45 g/cm³ 43.79-45.77.

EFFECT: development of composition of concrete mix for obtaining of fireproof coating with high heat-resistance, having the improved physico-mechanical characteristics and allowing to increase the limit of fire resistance of ferroconcrete structures.

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Description

The invention relates to the oil and gas industry, in particular to the technology of creating downhole filters in deep wells, which revealed unstable weakly cemented reservoir rocks. Scope: gas and oil fields, underground gas storages and industrial landfills.

Known methods for creating gravel-slotted filters on Av. St. SU No. 1712590, Av. St. No. 1470937, including the installation of a slit filter and washing the material behind it.

The disadvantage of these methods is the low productivity of the well due to the reduction of its diameter when installing a slotted filter in the interval of the perforated section of the casing string, the high complexity of the repair work.

A known method of fastening the bottomhole zone of a well according to patent RU No. 2172814, including the preparation of a cement slurry with an acid-soluble filler — shell rock with a fraction of 0.7-1.5 mm and a soluble filler — table salt with a fraction of 2-3 mm.

The main disadvantage of this composition is the fragility of the skeleton of cement stone due to the dissolution of hydrochloric acid additives together with cement, so the frame created by Portland cement is not strong enough and durable. It should be noted that the above addition of table salt does not dissolve during processing of the compositions with hydrochloric acid, for its dissolution, a repeated technological operation is necessary to inject water, which is not always acceptable in oil deposits.

Closest to the claimed composition is cement grouting high temperature reinforced according to patent RU No. 2375552, including wt.%: Portland cement grouting 66-75, quartz with a specific surface of 3500-4000 cm ² / g 25-34, reinforcing additive fiber 6 mm long 0, 25-0.30. The spatial framework resulting from the hydration of cement and quartz provides sufficient rigidity to pump water through it, and the addition of fiber reinforces the crack resistance of the face structure.

The disadvantage of this composition is that in the process of well development, the permeability of the created filter increases slightly and requires additional perforation.

The technical result of the invention is to ensure trouble-free operation of the filtering zone of the well (casing), increase the resistance to destruction of the filter elements while improving its fluid conductivity.

This technical result is achieved by solving a problem aimed at creating a stronger spatial frame formed by an active binder (a mixture of Portland cement and microdura), a fibrous filler of polymer (polypropylene) fiber with a diameter of 17-21 microns and a length of 12 mm PBEUROFIBER brand (Germany) interspersed with as a dry additive highly soluble and gas-forming when interacting with acids, salts, the amount of which increases with hydration and hardening of the binder, since mixing tseptury performed in a saturated salt solution above, and in the process of hardening the composition of water of the solution is taken binder component.

The technical problem is solved in that the composition for creating a downhole filter includes a binder - Portland cement, a fibrous filler - fiber, a highly soluble salt - potassium carbonate (potash), which has inclusions of natural isotopes (Chemical Encyclopedia, Volume 2, Moscow, 1990, p. 559), a moderator is boric acid with neutron-absorbing properties (Petrov M.M. et al. “Inorganic Chemistry”, 1989, p. 378), shuttered on a saturated solution of the above salt, Microdur at the following ratios of ingredients, wt.%:

Cementing Portland cement 43.79-45.77 Microdur 4,57-7,31 Fibrous Filler - Polymer (polypropylene) fiber with a diameter of 17-21 microns and a length of 12 mm 0.23-0.37 Highly Soluble Salt - Carbonate potassium (potash) K ₂ CO ₃ 2.29-2.92 Retarder - Boric Acid H ₃ BO ₃ 1.37-1.82 Saturated potassium carbonate solution K ₂ CO ₃ γ = 1.45 g / cm ³ 43.79-45.77

The essence of the invention lies in the fact that the composition for creating a downhole filter contains a binder - Portland cement, a fibrous filler - fiber, Microdur, a highly soluble salt - potassium carbonate (potash), which has inclusions of natural isotopes, a moderator - boric acid with neutron-absorbing properties, closed on saturated a solution of the above salt. The salt evenly distributed in the cement stone after its subsequent interaction with acid leads to the creation of well-permeable channels in the spatial framework due to the formation of bulk gaseous by-products that are removed, and acid residues and new salts resulting from the reaction. The use of potassium carbonate (potash), which, reacting with acids, forms a lot of carbon dioxide and readily soluble salts, most fully meets these conditions.

Highly soluble salts used in the formulations, as a rule, are strong accelerators of grouting mortar, therefore, during the preparation of the mortar, it is necessary to add a moderator to its mixing fluid, for example, a boron-containing substance, which can be used as a neutron-absorbing indicator for measuring the interval before drilling the filter, and filter volume using neutron logging. As an indicator, potassium carbonate K ₂ CO ₃ can also be used, which contains the natural isotope K40 (0.0117%), and which can be measured by radio logging.

The binder “Mikrodur” is produced by air separation of dust generated during grinding of 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 the fluidity of water, even with a minimum amount of mixing liquid, which allows the suspension "Mikrodur" to penetrate into the low permeable rock. The expiration time (conditional viscosity) of a suspension under the age of 3 hours ranges from 28 to 30 seconds.

In contrast to the prototype, the use of a finely dispersed binder "Microdur" allows you 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 15000-25000 cm ² / g against 0.3-0.5 conventional grouting cements having a specific surface area of 3000-3500 cm ² / g.

At the same time, the Mikrodur additive less than 4.57 wt.% Reduces the strength of the formed stone, the addition of more than 7.31 wt.% Leads to a thickening of the composition, in addition, a polymer substance is used in the composition of the borehole filter - fiber, which allows Mikrodur ”And Portland cement form a sufficiently strong frame. Moreover, the introduction of less than 43.49 wt.% In Portland cement reduces the strength of the frame, and more than 45.77 wt.% Makes it difficult to pump the composition into the well.

The addition of fiber is more than 0.37 wt.% Makes it difficult to sell the composition into the reservoir, with the addition of less than 0.23 wt.% It dilutes the composition and reduces its ability to be fixed in the reservoir.

Mixing "Mikrodur" with Portland cement is performed on a saturated solution of the highly soluble salt of K ₂ CO ₃ . Its ability to quickly dissolve in water or react violently with hydrochloric acid with the release of a large amount of CO ₂ leads to the formation of a porous skeleton from the composition injected into the well, and the use of a solution of less than 43.79 wt.% Creates an un pumpable composition, and more than 45.77 wt. % degrades the strength of the frame.

To enhance the above properties, dry salt K ₂ CO _{3 is} added to the dry binder. The addition of K ₂ CO ₃ less than 2.29 wt.% Reduces the ability of the composition to form a porous stone. The addition of K ₂ CO ₃ more than 2.92 wt.% Leads to premature setting of the composition.

Since K ₂ CO ₃ is a strong hardening accelerator for Portland cement and Mikrodur, a moderator has been added to the composition. With additives of less than 1.37 wt.%, The injected composition can lead to early thickening and setting before filling into the formation. Boric acid is used as a retarder. Its addition of more than 1.82 wt.% Can lead to delamination of the composition.

The preparation of the composition for creating a downhole filter is carried out directly at the well. The composition is prepared in the usual way using a clay mixer or aggregate-mixing machine, for example, ASM-25, (USO-20), into which the components are successively introduced: water, K ₂ CO ₃ salt, boric acid, fiber, Microdur, Portland cement.

Determination of the basic properties of the mortar and stone is carried out in accordance with GOST "Cement grouting", "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 ° C and atmospheric pressure. Spreadability is determined by the cone of the 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 (Model 4207D-CHANDLER), gas permeability GFS-830-SS-CHANDLER. Neutron moderation was measured using the INK (pulsed neutron logging) instrument and the INGK (pulsed neutron gamma-ray logging) device.

When conducting laboratory tests were used:

- tap water;

- Microdur;

- grouting cement;

- potassium carbonate K ₂ CO ₃ ;

- boric acid;

- fiber fiber with a diameter of 17-21 microns and a length of 12 mm of the PBEUROFIBER brand (Germany).

Note: After the permeability test, the samples were tested for compression, the value of which was 4-6 MPa.

Example.

To prepare the solution (composition 5, Tab. 1) in a solution density of 1.45 g / cm ³ (110 g K ₂ CO _3/100 cm ³ of water) weighing 100 g are added 0.5 g of fiberglass, 5 g of potassium carbonate, 3 g of boric acid, a mixture of 10 g of Mikrodur and 100 g of Portland cement. The composition is stirred for 3 minutes, after which the spreadability, density, and pumpability are determined at a temperature of 75 ° C and atmospheric pressure.

After repeated preparation, samples are formed for testing for strength after 2 days of hardening and for permeability after 5 days of hardening in a saturated solution of potassium carbonate. After determining the initial permeability, the samples are placed in water for 5 days, and then determine the five-day permeability, at the same time check the permeability after placing the samples for 0.25 days in hydrochloric acid.

The test results of composition 5 are shown in table 1. The density of the composition is 2.03 g / cm ³ , spreadability 24 cm, pumpability 2 h 50 min, compressive strength 12 MPa, initial permeability less than 0.1 μm ² .

After 5 days of storage in water or 0.25 days in hydrochloric acid, γ = 1.12 g / cm ^{3 the} permeability increased to 200 μm ² . After permeability tests, the samples were tested for compression, the value of which was 4.0-6.0 MPa.

The proposed composition allows to obtain high-quality creation of a filter zone of wells, to prevent sand occurrence in production oil wells, siltation in wells intended for the injection of industrial effluents.

Claims (1)

The composition for creating a downhole filter, including a binder - Portland cement, a fibrous filler - fiber, additionally contains Microdur, a highly soluble salt - potassium carbonate (potash) having natural isotope inclusions, a moderator - boric acid with neutron-absorbing properties, shuttered on a saturated solution of the above salt, when the following ratio of ingredients, wt.%:
Cementing agent - Portland cement 43.79-45.77 Microdur 4,57-7,31 Fibrous Filler - Polymer (polypropylene) fiber with a diameter of 17-21 microns and a length of 12 mm 0.23-0.37 Highly Soluble Salt - Carbonate potassium (potash) K ₂ CO ₃ 2.29-2.92 Retarder - Boric Acid H ₃ BO ₃ 1.37-1.82 Saturated potassium carbonate solution K ₂ CO ₃ γ = 1.45 g / cm ³ 43.79-45.77