High-strength low-hydration-heat low-density cement paste system for well cementation, and preparation method thereof

Abstract

The invention provides a high-strength low-hydration-heat low-density cement paste system for well cementation, and a preparation method thereof. The high-strength low-hydration-heat low-density cement paste system comprises, in parts by weigh, 25-35 parts of low-hydration-heat Portland cement, 20-25 parts of glass beads, 25-30 parts of slag powder, 8-10 parts of silica fume, 3-5 parts of calcined gypsum, 1-2 parts of sodium sulfate, 1-2 parts of quick lime, 2-3 parts of slaked lime, 2-3 parts of sodium metasilicate, 0.5-1.5 parts of sodium carbonate and 65-75 parts of water. Admixtures such as a retarder, a fluid loss agent and a drag reducer can be added into the system as required. The prepared cement paste system is low in density (1.20-1.30 g / cm<3>), and it is ensured that a wellbore annulus is completely sealed through one-time upward returning; the strength of the system is high (the strength at a normal pressure and a temperature of 45 DEG C within 24 h or within 48 h is larger than 7 or 10 MPa), and a sleeve can be better supported; and the cement paste system is suitable for cementing operation of oil and gas wells within a temperature range of 50-90 DEG C. The performance conflict between a retarder and a coagulation accelerating activator used in an existing cement paste system is eliminated, the thickening time of the system is convenient and adjustable, and the well cementation quality of oil and gas wells is improved.

Description

technical field [0001] The invention belongs to the technical field of well cementing, and in particular relates to a high-strength, low-heat-of-hydration, low-density cement slurry system for well cementing and a preparation method and application thereof. Background technique [0002] With the process of petroleum exploration and development, more and more formations prone to leakage, such as low-pressure formations and weak formations, are encountered, and the low-density cement slurry system is gradually developed and perfected along with the treatment of these complicated situations. With the continuous development and promotion of deep well and ultra-deep well technology, leakage-prone formations in deep and ultra-deep wells often cause serious lost circulation, which seriously affects the quality of cementing and the implementation of subsequent stimulation operations. To improve the cementing quality of such complex well conditions, it is necessary to improve the low...

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Problems solved by technology

[0005] The second object of the present invention is to provide a high-strength, low-heat-of-hydration, low-density cement slurry system comprising the above-mentioned low heat-of-hydration portland cement , solve the defects of the existing low-density cement slurry system, eliminate the performance conflict between the retarder and the coagulation accelerator activator used in the system, realize the convenient adjustment of the thickening time of the system, and improve the cementing quality and production efficiency of oil and gas wells

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