High temperature resistance low-density high-strength cement paste

Abstract

The invention discloses high temperature resistance low-density high-strength cement paste which consists of the following components in parts by weight: 100 parts of cement, 23 to 35 parts of lightening admixture, 30 to 40 parts of high temperature strength stabilizer, 10 to 23 parts of filler, 1.5 to 2 parts of dispersing agent, 1 to 2 parts of early strength agent and 8 to 15 parts of fluid loss agent, wherein hollow microspheres are used as the lightening admixture; the high temperature strength stabilizer is high-activity silicon powder; the filler is micro silicon; the dispersing agent is an aldehyde ketone condensation product or a naphthalene dispersing agent; the early strength agent is formed by blending two or more of the following components: sulfo-aluminium sulfate, sodium silicate, basic aluminium chloride and the like; and the fluid loss agent is a sulphonated acetone-formaldehyde condensation product. The low-density cement paste can be used for well cementation of a heavy oil thermal recovery well on a low-pressure formation which is easy to leak, the strength recession of cement stones, which is caused by the high temperature, can also be greatly reduced, and the service life of the oil well is prolonged.

Description

technical field [0001] The invention relates to cement, in particular to a high-temperature-resistant, low-density, high-strength cement slurry suitable for thermal recovery well cementing. Background technique [0002] During the exploitation of heavy oil, the temperature of the superheated steam injected into the formation is as high as 250°C. At such a high temperature, the strength of ordinary Portland oil well cement will decline sharply, resulting in the loosening of the cement stone and a significant decrease in strength. The formation is effectively isolated, the interlayer fluids communicate with each other, and the wellhead emits gas when steam is injected, which shortens the life of the oil well and reduces the production efficiency and recovery factor. Therefore, heavy oil thermal recovery wells need to be sealed with high temperature resistant cement slurry. Adding silica fume (quartz sand) to cement can effectively improve the thermal stability of cement stone...

AI Technical Summary

Problems solved by technology

[0006] Although low-density cement slurry cementing technology has developed rapidly at home and abroad, there is still room for improvement in high-temperature thermal recovery well cementing. Most low-density cement slurry systems have insufficient high-temperature resistance (>200°C), and cement stone strength at high temperatures severe recession

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