SU1258987A1 - Cementing composition for boreholes - Google Patents

Abstract

The invention relates to an oil and gas production & A & A, and is intended for cementing wells. The purpose of the invention is to increase the density of the cement slurry, increase the thickening time and ensure curing without breaking at 50-150 0. The cement slurry (TP) contains magnesia cement, magnesium chloride, an additive and water. For the preparation of TP, metallurgical magnesite powder with a specific surface area of 315-385 is used. Sulfuric iron is used as an additive. Thus, the TP lc is the ingredients, I in the following ratio, wt.%: Metallurgical magnesite 60-66, sulfuric acid iron 2-4, magnesium chloride 9-12, the rest is water. This ratio of ingredients allows to obtain a TP with a density of 2.25-2.28 g / cm. Sulfuric iron, introduced into TP, interacts with the constituents of TP, changes their solubility, and the reaction products form complex water-insoluble compounds. The strength of cement stone with increasing temperature from 50 to increases. There are no cracks on the surface of the samples. 2 tab. sl tsd ate 00 about 00

Description

The invention relates to the oil and gas sectors of the industry, to the field of well drilling, in particular to the compositions of cement slurries, and can be used for cementing wells with abnormally high formation pressures in the atiHe location of the horizontal horizons.

The aim of the invention is to increase the density of the solution, to increase the thickening time, to ensure solidity without destruction at 50-15 ° C.

The cement composition comprising sulfuric acid iron, in the following ratio of ingredients, wt.%:

Metallurgical

magnesite60-66

Magnesium chloride 9-12

c

Sulfuric acid iron 2-4 WaterOther

allows to obtain a cement slurry, with a density of 2.25-2.28 g / cm, and the strength of the cement stone, while keeping the temperature from 50-150 ° C, does not

however, it does not decrease, but even slightly increases (Table 1). In addition, on the surface of the samples, the appearance of cracks is not observed.

Dp of preparing the cement slurry using a ground solution — metallurgical magnesite with a specific surface area of 315-385. Table 2 presents data on the effect of the fineness of grinding metallurgical magnesite fia cement slurry properties.

Tests conducted by standard methods. Linear expansion was determined after 3 days of curing at a pressure of 30 MPa.

As a sulfuric acid iron, you can use the waste of the chemical or metallurgical industry (for example, the liquid phase is pickled after neutralization of sulfuric acid). The waste is a pale yellow crystalline powder, highly soluble in water at normal temperature. The content of basic salt in these wastes is up to 95%.

The sulfuric acid iron (oxide or acidic) introduced into the cement slurry interacts with the components of the cement slurry, changes their solubility, and the interaction products form complex water-insoluble compounds (“Eni”, which somewhat slow down the rate of hydration in the early period of hardening).

to

15

20

25

neither, since they block the access of the mixing fluid to the grains of magnesite and the crystalline nuclei of hydrate tumors. In the future, this contributes to an increase in the thickening time, as well as an increase in the failure rate, water and salt resistance of the cementing stone hardening in the range of 50–150 ° C. and low dissolution rate in the mixing fluid. All this provides the cement slurry with the required thickening time at hardening temperatures of 50-150 ° C, and the density of the initial components and the accepted dosages of them ensure the production of cement slurry with a bulk density (up to 2300 kg / m) without the introduction of a special equipment and obtaining cement stone hardening without destruction in a given temperature range.

Example 1 12% by weight of magnesium chloride are dissolved in 24% by weight of water. 4% by weight of sulfuric iron is introduced into the resulting solution. This solution was used to shutter 60 of us, 7 metallurgical magnesite, previously ground to a specific surface of 350 + 20 m / kg.

The density of the resulting cement slurry is 2.28 g / cm. Time of thickening at 50 C 3h

48 min, at 150 C 1 h 56 min. Flexural strength after two days at 504 10.1 MPa, at 10.3 MPa, at 150 C 7.4 MPa.

Flexural strength after 28 days of aging in water at 11.8 MPa, at 9.0 MPa. No cracks were observed after 28 days in water.

Example 2 11% by weight of magnesium chloride are dissolved in 23% by weight of water. The resulting solution is injected with 3% by weight sulfuric acid iron. This solution gate np-63 wt.% Metallurgical magnesite.

The density of the obtained cement slurry is 2.27 g / cm. The time of thickening at 3 h 26 min, at 150 C 1 h 42 min. Flexural strength after two days at 10.4 MPa, at SO-S P, 9 MPa, at 9.5 MPa. Durability at izhibi in 28 days vosherzhipani in vo30

40

45

50

55

3

de at 50 ° C is 12.1 MPa, pr 150 ° C 10.9 MPa. There are no cracks after 28 days in water at 150 ° C.

Example 9% by weight of magnesium chloride is dissolved in 23% by weight of water. 2% by weight of sulfuric acid iron is added to the resulting solution. This solution shutters 66% by weight of metallurgic magnesite.

The density of the resulting tampon solution was 2.25 g / cm. The thickening time at 50 ° С was 3 hours and 7 minutes, and at 150 ° C, 1 hour T5 minutes. Flexural strength after two days

prc 9.6 MPa, at 11.2 MPa at 150 ° С 10.3 MPa. Flexural strength after 28 days of retention in water at 9.2 MPa, at 9.8 MPa. There are no cracks after 28 days in water at 150 ° C.

Example 4 12% by weight of magnesium chloride are dissolved in 24% by weight of water. 5% by weight of sulfuric iron is introduced into the resulting solution. This solution is shuttered May 59 by metallurgical magnesite.

The density of the resulting cement slurry is 2.28 g / cm. Cooking time at 3 h 55 min, at 2 h 10 min. Flexural strength after two days of hardening at 9.8 MPa, at 1001 11.2 MPa, at 150 C 7.0 MPa. Flexural strength after 28 days of aging in water at MPa, at 9.2 MPa. Cracking through 28 cVT holding in water was not observed.

EXAMPLE 5 May 9 L of nitride chloride is dissolved in 23% by weight of water. 1% by weight; sero-acid iron is introduced into the resulting solution. This solution

shutter are 67 May. magnesite.

metallurgical

The density of the resulting cement slurry is 2.25 g / cm. 3 times thickening at 50 ° С 2 h 45 min 50 at 150 ° C 50 min. Flexural strength after two days of hardening at 1.25 MPa, at 100 ° C and 11.4 MPa, at 150 C 10.5 MPa.

Flexural strength after 28 days of retention in water at 7.7 MPa, at 150 C, 6.9 MPa. Cracks are observed after 28 days in water at 150 s.

The content of metallurgical magnesite in quantities of less than 60 wt.% And more than 66 wt.% Does not provide the desired consistency of cement paste and its density within the specified limits (2.25-2.28 g / cm).

The content of magnesium chloride within the specified limits is due to the preparation of a solution of mixing viscosity with a density of 1, 30 g / cm. When the density of the solution is formed, a hardly soluble mixture is formed. The solution with a lower density does not provide high strength cement stone.

The content of sulfuric acid iron in quantities of less than 2 wt.% Does not provide the crack resistance of the cement stone, more than 4 wt.% Is not economically feasible.

Cement slurry can be used for cementing wells with abnormally high reservoir pressures in the zone of sedimentary and salt deposits.

Claims (1)

Invention Formula Grouting mortar for fixing a well, containing magnesia cement, magnesium chloride, an additive and water, characterized in that, in order to increase the density of the solution, increase the thickening time, ensure solidification without destruction at 50-150 ° C, it is used as magnesia cement contains metallurgical magnesite ground to a specific surface 315 - 385, and as an additive it contains iron sulfate in the following ratio of ingredients, May. %: Metallurgical magnesite Magnesium chloride Sulfuric iron Water and MgO content 60-66 9-12 2-4 The rest in metallurgical magnesite is at least 78%. "A e" h n Note: The compositions contain 3% sulfuric acid iron. from the mixture of the cement solution., mixed with a solution of magnesium chloride with a density of g / cm, Editor V. Ivanova Compiled by L. Bestuzhev Tehred L. Oleiyih Corrector A. Obruchar Order 5101/33 Circulation 548 Halyard VRSHIPI USSR State Committee for inventions and discoveries 113035, Moscow Zh-35, Rau Ska nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 table 2