RU2470979C1 - Light-weight grouting mixture - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: light-weight grouting mixture includes the following component ratio, wt %: grouting Portland cement 51.50-64.54, condensed microsilica MK-85 21.52-34.34, calcium chloride 10.30-10.33, superplasticising agent - polyplast CP-1 2.57-2.58, natrosol 250 EXR 1.03-1.29.

EFFECT: improving insulating capability of light-weight grouting mixture due to reduced water loss, maintaining solution density at increased pressures; increasing the adhesion strength of stone to column and stone water impermeability.

1 ex, 1 tbl

Description

The invention relates to the fastening of oil and gas wells with abnormally low reservoir pressures (ANPD), namely, lightweight grouting mixtures with high insulating properties.

Known lightweight grouting mixture, including a binder and silica-containing additive, which contains waste from the production of ferrosilicon formed during the recovery of quartz in an electric arc (ed. St. 1507954, class E21B 33/138, publ. 15.09.89, bull. No. No. 34).

The disadvantage of this lightweight mixture is the high water loss, because cement slurry obtained from this mixture requires a higher water content and, as a consequence, low stone strength, with a density of the solution of 1.34-1.52 g / cm ³ .

The closest in composition and purpose is a lightweight grouting mixture containing grouting Portland cement, aluminosilicate microspheres, condensed silica fume MK-85 and granular calcium chloride. Facilitation of the mixture is achieved due to aluminosilicate microspheres / Patent No. 2255205, IPC E21B 33/138, publ. 06/27/2005 bull. Number 18.

The disadvantage of this lightweight mixture is the increased water loss of the prepared cement slurry, low adhesion of the stone to the column, a change in the density of the cement slurry at pressures of more than 15 MPa. The latter is due to the formation of microcracks on the surface of hollow aluminosilicate microspheres and the introduction of a part of the mixing liquid into the cavity of the microspheres with the dissolution of the gaseous component and a change in the ratio of solid and liquid phases. At the same time, in addition to increasing the density, there is an increase in the rheological parameters of lightweight grouting mortar.

These shortcomings do not allow for reliable isolation of the annulus and can be the cause of hydraulic fracturing and under-rise of the solution to the design height.

When creating the invention, the problem was solved of improving the quality of fastening of casing strings in the interval of permeable formations with ANPD and formations with low hydraulic fracturing gradients.

The technical result of the invention is the development of lightweight cement mixture with increased insulating ability due to reduced fluid loss of the solution, maintaining the density of the solution at elevated pressures, increased adhesion of the stone to the column and the waterproofness of the stone.

The solution to this problem is achieved by the fact that the facilitated grouting mixture includes grouting Portland cement, MK-85 silica fume, calcium chloride, superplasticizer SP-1 and natrosol water loss reducer in the following ratio, wt.%:

Portland cement grouting 51.50-64.54 Condensed silica fume MK-85 21.52-34.34 Calcium chloride 10.30-10.33 Superplasticizer SP-1 2.57-2.58 Natrosol 250 EXR 1.03-1.29

The mutual influence of the components on each other, their synergistic effect in this mixture makes it possible to obtain a light (due to silica fume MK-85) mixture, from which a sedimentation-stable solution, stable in density over time (due to natrosol and calcium chloride), and a stone with increased traction and water resistance.

The superplasticizer SP-1 plays the role of a regulator of rheological properties and, in combination with calcium chloride and 250 EXR natrosol, allows for low water loss and permeability of the stone at specified hardening periods. The combination of superplasticizer SP-1, silica fume MK-85 and calcium chloride provides increased adhesion of the stone to the column due to increased dispersion of silica fume MK-85 and the formation of cement stone with a more uniform structure.

To prepare the grouting mixture, PCT 1-50 portland cement was used according to GOST 1581-96 of Sukholozhskcement OJSC, MK-85 silica fume according to TU 5743-048-02495332-96 of Bratsk Ferroalloys Plant LLC, and calcium chloride according to GOST 450 as an accelerator -77, to reduce filtration - natrosol 250 EXR according to TU 2231-001-32195737-2005 of NTF “Cellulose ethers” OJSC, as a plasticizer - superplasticizer “Polyplast SP-1” according to TU 5870-005-58042865-05 LLC “Polyplast- UralSib "Pervouralsk.

The basic properties of lightweight grouting mortar and stone prepared from lightweight grouting mixture were determined at a test temperature of (20 ± 2) ° C in accordance with GOST 26798.1-96 Cement grouting. Test Methods. " Density was determined using an ABR-1 type hydrometer according to the procedure provided for by the hydrometer operating instructions, flowability was determined by the shape of a cone, sedimentation stability was determined by water separation in a cylinder with a capacity of 250 ml, water loss per 30 min using a VM-6 device. The ultimate strength of the stone in bending and compression was determined on a testing machine to determine the compressive / bending strength of cement manufactured by CONTROLS, and the adhesion to metal was determined using a P-10 hydraulic press. Water permeability was determined on a device for determining the permeability of cement stone of the company "CHANDLER ENGINEERING" model 2030 according to the procedure provided for in the instructions of the device.

Lightweight cement mixture was prepared as follows. A dry mixture of grouting portland cement, MK-85 silica fume, calcium chloride, SP-1 superplasticizer and 250 EXR natrosol in the given proportions were thoroughly mixed and closed with a measured amount of mixing liquid (at B / C = 1.5) in a laboratory mixer SL-1. After that, the parameters of the solution and the properties of the formed stone were measured.

A mixture of the prototype is also prepared in the laboratory and measured parameters not shown in the patent.

Example. To prepare 1 kg of lightweight cement mixture (table, composition 1), it is necessary to prepare a dry mixture of 516.4 g of cement Portland cement, 344.2 g of silica fume, 103.3 g of calcium chloride, 25.8 g of SP-1 and 10.3 g natrosol. The composition is mixed for three minutes (at B / C = 1.5) and determine the density, spreadability, water separation and water loss. The solution is poured into molds to determine the strength of the stone by bending, compression, adhesion, and into molds for permeability testing. Samples are kept in a thermostat at a temperature of 20 ± 2 ° C until the test time.

The prepared composition has a density of 1.30 g / cm ³ , flowability 300 mm, water separation of 0.0 ml, water loss of 26.0 cm ³ . Bending strength - 0.75 MPa, compressive strength - 2.2 MPa, adhesion strength - 0.8 MPa, water permeability of 0.0006 × 10 ^-3 μm ² .

Examples of preparation and testing of the remaining compositions shown in the table are similar to the above.

To identify the distinguishing features and the positive effect, the mass ratios of the ingredients were changed.

As can be seen from the table, the inventive lightweight cement mixture (at B / C = 1.5) with an optimal ratio of components has better properties than the prototype, namely, it is characterized by increased insulating ability due to reduced fluid loss of the solution (26.0 cm ³ ), maintains the density of the solution at elevated injection and forcing pressures, and waterproof, with increased adhesion, stone with a column (0.8 MPa). The solution of the prototype has an increased water loss (108 cm ³ ), the stone formed from the solution is water permeable and is characterized by low adhesion of the stone to the column (0.4 MPa).

Equal amounts of portland cement cement and silica fume MK-85 and a decrease in the amount of superplasticizer SP-1 and natrosol 250 EXR in the composition of the proposed lightweight mixture lead to a decrease in water loss (15.4 cm ³ ), but the spreadability decreases (170 mm) and the density of the solution increases (1.40 g / cm ³ ). The maximum values of Portland cement grouting and superplasticizer SP-1 in the mixture lead to a higher value of water loss (50 cm).

Thus, lightweight grouting mixtures with acceptable technological characteristics can be prepared from grouting Portland cement, MK-85 silica fume, calcium chloride, SP-1 superplasticizer and Natrosol 250 EXR, which can be used to fix casing strings in the interval of permeable formations with ANPD and formations with low fracturing gradients.

Table 1 Technological properties of lightweight cement mixture with silica fume MK-85, superplasticizer SP-1, natrosol 250 EXR and calcium chloride No. p / p The composition of lightweight cement mixture, wt.% Raft
g / cm ³ Spreadability, mm Water drain
division, ml Water loss in 30 min, cm ³ Strength, MPa,
2 days The permeability of the stone, 2 days,
10 ^-3 μm ² PCT 1-50 MK-85 calcium chloride SP-1 250 EXR bend compression grip
nie one 51.64 34.42 10.33 2,58 1,03 1.30 300 0,0 26.0 0.75 2.20 0.8 0,0006 2 64.54 21.52 10.33 2,58 1,03 1.32 275 0,0 17.5 0.8 2.20 0.9 0,0004 3 51.50 34.34 10.30 2,57 1.29 1.30 200 0,0 20,0 0.7 2.10 0.8 0.0001 Outrageous values four 45.13 45.13 7.22 1.81 0.71 1.40 170 0,0 15.4 1.4 3.2 1,2 0,0008 5 60.08 25.75 10.30 2,58 1.29 1.32 276 0,0 50,0 0.7 2.1 0.8 waterproof. Prototype 6 78.1 4.9 2,4 Asm - 14.5 1.45 225 0.8 108 1.3 3.4 0.4 0,0540

Claims (1)

Lightweight grouting mixture, including grouting Portland cement, silica fume MK-85, calcium chloride, superplasticizer SP-1 and water loss reducer natrosol in the following ratio, wt.%:
Portland cement grouting 51.50-64.54 Condensed silica fume MK-85 21.52-34.34 Calcium chloride 10.30-10.33 Superplasticizer SP-1 2.57-2.58 Natrosol 250 EXR 1.03-1.29