RU2243358C1 - Lightened cementing mixture - Google Patents

Abstract

FIELD: oil and gas extractive industry.

SUBSTANCE: mixture contains, in percents of mass: Portland cement 85-89.5, expanded vermiculite sand 2-5, alumosilicate microspheres 2-5, granulated calcium chloride, as stabilizing admixture, - the rest.

EFFECT: higher stability and efficiency.

1 tbl

Description

The invention relates to the oil and gas industry and can be used for cementing oil, gas and gas condensate wells in the presence of formations with different pressures.

Known lightweight cement mixture, including portlancement, expanded vermiculite sand, aluminosilicate microspheres [RF Patent 2187621, E 21 B 33/13, 2000].

Although this mixture is characterized by reduced water separation, however, it has drawbacks such as low stability of the cement slurry due to sedimentation of Portland cement with the simultaneous emergence of vermiculite and aluminosilicate microspheres, as well as a high filtration rate. Low stability of the solution contributes to the formation of inter-layer flows and intercolumn oil and gas occurrences during the period of waiting for cement solidification (OZZ), and a high filtration rate to the formation of permeable cement stone. Together, these shortcomings lead to a decrease in the quality of reservoir separation and a reduction in the overhaul period of wells.

When creating the invention, the problem was solved of improving the quality of separation of the layers by increasing the stability of the cement slurry and reducing the filtration rate.

The technical result of the invention is the development of lightweight cement slurry with high stability and low filtration rate.

The solution to this problem is achieved in that a lightweight cement mixture, including Portland cement, expanded vermiculite sand and aluminosilicate microspheres, additionally contains granular calcium chloride as a stabilizing additive in the following components, wt.%:

Portland cement 85-89.5

Expanded Vermiculite Sand 2-5

Aluminosilicate microspheres 2-5

Granular Calcium Chloride

Granular calcium chloride is produced according to TU 609-4711-81 and represents white granules with an active substance content of at least 90%.

The preparation of a lightweight mixture is carried out centrally in the workshop of dry cement compositions. For this, for example, 850 kg of Portland cement, 50 kg of expanded vermiculite sand, 50 kg of aluminosilicate microspheres and 50 kg of granular calcium chloride are alternately loaded into the mixing chamber to obtain a mixture in the amount of 8000 kg. Then the components are mixed for 30-40 minutes and, the homogeneous mixture is prepared, dried with compressed air is fed into cement trucks or into bunkers of cement-mixing machines. If necessary, in the field conditions an additional repacking of the mixture from one cement mixing machine to another is performed.

Known lightweight grouting mixtures were prepared, including Portland cement, expanded vermiculite sand and aluminosilicate microspheres, and three compositions of the lightweight grouting mixture in accordance with the invention (Portland cement, expanded vermiculite sand, aluminosilicate microspheres and granular calcium chloride) with a boundary and average value of the components. The preparation of cement slurry samples, the determination of the density of the cement slurry and the strength of the cement stone were carried out in accordance with GOST 26798.0-26798.2-96.

Stability was determined by the difference in density of the upper and lower parts of the column of cement slurry in accordance with the method proposed in the work of Bulatov A.I. Management of physical and mechanical properties of cement systems. - M .: Nedra, 1976, p. 65-67.

The rate of filtration of the cement slurry was measured in accordance with the method proposed in the work Danyushevsky B.C., Aliev P.M., Tolstykh I.F. Reference manual for grouting materials. - M .: Nedra, 1987, p. 244-246, and was expressed by the value of the conditional filtration for 30 minutes.

The test results are presented in the table. The data obtained indicate that the proposed grouting mixture with an optimal ratio of components has better properties than the known one, namely, it is characterized by high stability of the grouting mortar and a lower (1.5 times) filtration rate.

Claims (1)

Lightweight grouting mixture, including Portland cement, expanded vermiculite sand and aluminosilicate microspheres, characterized in that it additionally contains granular calcium chloride as a stabilizing additive in the following ratio, wt.%: Portland cement 85 - 89.5 Expanded Vermiculite Sand 2 - 5 Aluminosilicate microspheres 2 - 5 Granular Calcium Chloride