RU2244098C1 - Light-weight grouting mortar - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to grouting mortars used for cementing casing pipes of gas, gas-condensate, and oil wells complicated by presence of formations with low hydraulic rupture pressure as well as presence of permafrost rocks. Light-weight grouting mortar contains 47.0-60.0% special-type cement, 6.6-11.8% clinoptilite as light-weight additive, and water. As a result, casing-pipe annulus incidents during boring and running wells are avoided owing to improved parameters of grouting cement, in particular increased sedimentation stability of mortar, dimensional stability and needed strength of cement stone at low positive and negative temperature in early hardening stages are achieved at simultaneous lowering of grouting mortar density.

EFFECT: improved performance characteristics of grouting mortar.

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Description

The invention relates to cement slurries used in cementing casing strings of gas, gas condensate and oil wells, complicated by the presence of loosely coupled, prone to hydraulic fracturing of rocks, as well as rocks with low positive and negative temperatures.

Known lightweight grouting mortar [1], containing Portland cement, facilitating a mineral additive - hydrophobized clinoptilolite clay in the following ratio of components in solution, wt.%:

cement 30.0-40.0

hydrophobized

clinoptilolithoglydic rock 13.0-23.0

water rest

The disadvantages of the known solution is its shrinkage in the hardening process, resulting in deterioration of the adhesion of cement stone with casing and low sedimentation stability for geocryological conditions.

The closest in composition and purpose is cement slurry of low density [2], containing cement slurry TsNUB, facilitating the mineral additive - vermiculite.

A disadvantage of the well-known cement slurry is that vermiculite is an inert filler that does not participate in cement hydration reactions, and therefore does not increase its strength.

The objective of the invention is to improve the parameters of lightweight grouting mortar and stone, providing high-quality cementing of casing strings in the permafrost interval (MMP), preventing annular manifestations, raising cement to the wellhead.

The technical result of the claimed invention is to increase the sedimentation stability and strength of cement cement, reducing contraction.

The essence of the invention lies in the fact that the inventive lightweight cement slurry includes cement slurry TsNUB, facilitating the additive - zeolite-containing rock clinoptilolite, actively involved in the structure formation of cement, and water, in the following ratio, wt.%: Cement low-temperature TsNUB - 60,0- 47.0; clinoptilolite - 6.6-11.8; water is the rest.

A comparative analysis with the prototype allows us to conclude that the inventive lightweight cement slurry differs from the known introduction of new components, namely clinoptilolite in the above ratio of components, i.e. The claimed invention meets the criterion of "novelty."

Grouting cement TsNUB contains: finely ground gypsum-free Portland cement clinker (90%), burnt solid residue of soda production (10% of the clinker content), plasticizing additive - NTF (0.1-0.13% of the weight of the dry mixture), electrolyte-soda ash (3.8-5.0% by weight of the dry mixture). Cement production TsNUB established at Sterlitamakskom JSC “Soda”.

By composition, zeolites are framework aluminosilicates, in particular clinoptilolite - (Na, K) ₄ Ca Al ₆ Si ₃₀ O ₇₀ 24 H ₂ O. It is a natural microporous framework silicate, and there are four types of capillary-sized channels in its structure. The main structural parameters of clinoptilolite are as follows: the effective diameter of the entrance windows is 0.43-0.35 nm; the volume of free intracrystalline space is 30-40%. Clinoptilolite lies in thick strata in many deposits of zeolitized tuffs (Sokornitsa, Tedzami, Eastern Siberia, etc.).

The action of clinoptilolite additive consists not only in lowering the density of the solution, but also in reducing contraction and hardening of cement stone.

This is because in zeolites, as a rule, part of the silicon ions is replaced by aluminum. Such a substitution leads to the appearance of an excess negative charge, which must be neutralized by an additional ion located in the intracrystalline cavities of the structure. In addition, ion-exchange centers can occur on the surface of minerals due to deviations from electroneutrality at the phase boundaries. The presence of a charge on the outer surface facilitates the interaction of clinoptilolite particles with ions and associates of a cement dispersion sol. The physicochemical state of colloidal particles in the cement-zeolite solution meets the conditions for the subsequent formation of strong single contacts in the stone microstructure, the hydration process is constantly resumed on the zeolite sites cleared of neoplasms.

Since cement slurry of TsNUB is mainly represented by calcium oxide, whose solubility at low temperatures is quite high, its interaction with the surface of clinoptilolite particles with the formation of hydrated compounds is assumed. Thus, clinoptilolite will contribute to the creation of a lightweight cement slurry forming a stone with increased strength and insulation properties.

The high content of active calcium oxide in the calcined solid residue of soda production activates the hardening process of gypsum-free Portland cement, increases its sedimentation stability and provides the expanding properties of cement stone.

Comparison with known grouting solutions was carried out for compositions that meet the requirements of GOST 1881-96 for the density of lightweight grouting mortars.

The experimental data presented used cement grouting TsNUB according to STP-1-39-91 (PO Arktikmorneftegazrazvedka), zeolite according to TU 113-12-98-852, tap water according to GOST 2874-82.

Comparison with the known mortar was made by density, spreadability, water separation, the setting time of cement slurry and the strength of the stone formed from it. All compositions (known and claimed) have the same hardening conditions, samples at a temperature of minus 2 ° C and atmospheric pressure. The basic properties of lightweight grouting mortar and stone were determined in accordance with GOST 267981-96, 267982-96 “Cement grouting”, “Test methods” and the technique proposed in [3]. The density of the grouting mortar is determined by an AG-1 hydrometer, the spreadability is determined by the cone of the AzNII, the setting time by the Vika device, the tensile strength of the grouting stone by the MII-100 testing machine, and water separation is measured using measuring cylinders.

To identify the distinguishing features and technical result, the mass ratios of the ingredients were changed in a wide range of values.

Lightweight cement slurry is prepared as follows. The required amount of zeolite is mixed with cement TsNUB, and then the mixture is shut with water at a given water-cement ratio.

Example:

To prepare 1 kg of lightweight cement slurry (composition No. 6), you need to take 601 g of cement TsNUB mix with 66 g of zeolite (clinoptilolite) and mix 333 g of water.

The composition is stirred for 3 minutes, after which its density, spreadability and water separation are determined. To determine the setting time, the ultimate strength of the cement stone for bending, the prepared solution is poured into molds and kept at a temperature of minus 2 ° С. The cement stone is tested for strength after 2 days from the beginning of its mixing. The test results are shown in the table.

Prepared composition 6 has a density of 1660 kg / m ³ , spreadability - 180 mm, setting time after 7 hours and 15 minutes, setting time - 10 hours, the bending strength of the stone is 0.95 MPa, water separation - 1.4%. No shrinkage of cement was observed.

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 ratio of the ingredients was changed in a wide range of values. It was found that the compositions of solutions No. 6, 10, 14, 15 are optimal.

As can be seen from the table, the claimed cement slurry has a reduced water separation from 0.0% (composition 14) to 1.4% (composition 6) at a density of 1610-1660 kg / m ³ . The strength of the stone formed from the inventive cement is in the range from 0.90 MPa (solution No. 15) to 0.97 MPa (solution No. 10) at a density of 1510-1640 kg / m ³ .

The proposed cement slurry can improve the quality of fastening of low-temperature wells and prevent under-raising of cement to the wellhead, which occurs during cementing with known compositions.

Comparative characteristics of the known and proposed lightweight grouting mortar (test temperature -2 ° C) No pp The composition of the cement slurry, wt.% Density, kg / m ³ Spreadability
mm Setting time, hour-min. Strength, MPa
· (2 days) Water separation,% TsNUB Lightweight additive Water Start the end Known lightweight grouting mortar (prototype) 1. 59.4 Vermiculite
3,1 37.5 1600 200 5-25 11-10 0.90 7.4 Suggested lightweight grouting mortar 2. 63,4 3, .3 33.3 1740 190 6-20 8-15 1.10 2,4 3. 59.4 3,1 37.5 1620 240 6-30 9-30 1.00 4.7 4. 55.9 2.9 41.2 1510 250 6-35 9-55 0.90 6.0 5 64.3 7.1 28.6 1780 170 5-40 8-25 1.06 0,0 6. 60.1 6.6 33.3 1660 185 7-15 10-00 0.95 1.4 7. 56.3 6.2 37.5 1550 240 7-20 10-20 0.81 4.1 8. 52.9 5.9 41.2 1490 250 7-20 10-40 0.85 5.3 9. 60.7 10.7 28.6 1750 170 6-30 9-00 1,0 0,0 10. 56.7 10.0 33.3 1640 185 6-50 9-35 0.97 0.5 eleven. 53.1 9,4 37.5 1530 230 7-10 10-30 0.91 2,3 12. 50,0 8.8 41.2 1470 250 7-25 10-45 0.88 3.6 thirteen. 57.1 14.3 28.6 1720 165 6-50 9-45 1,0 0,0 14. 53,4 13.3 33.3 1610 180 6-45 10-00 0.92 0,0 fifteen. 50,0 12.5 37.5 1510 215 7-40 10-30 0.90 0.9 16. 47.0 11.8 41.2 1440 240 7-20 10-50 0.80 2,4

Sources of information:

1 A.S. USSR No. 1099051, class E 21 B 33/138.

2 Ovchinnikov V.P., Frolov A.A., Shatov A.A., Vyakhirev V.I., Sorokin V.F., Ovchinnikov P.V. Salt and grouting compositions based on secondary material resources of soda production. - M .: Nedra-Business Center LLC, 2000. - 214 p.

3. Klyusov A.A., Lepnev E.N., Nikulin V.Ya. and other Features of the test of cementing materials for low-temperature wells // Overview. Series “Drilling gas and gas condensate wells”. - M.: VNIIEGazprom, 1989, No. 2, 30 p.

Claims (1)

Lightweight cement slurry, including cement slurry TsNUB, facilitating the mineral additive - zeolite-containing rock and water, characterized in that as zeolite-containing rock contains clinoptilolite in the following ratio, wt.%: Cement TsNUB 47.0-60.0 Clinoptilolite 6.6-11.8 Water Else