Cement expansion agent suitable for high temperature environment and preparation method thereof

Abstract

The invention discloses a cement expansion agent suitable for a high temperature environment and a preparation method thereof. The cement expansion agent comprises the following components by mass percent: 85.0%-99.5% of a magnesium material, 0.5%-10.0% of a silicon material, 0-0.50% of an expansion inhibitor and 0-5.0% of a calcium material, wherein the magnesium material is prepared from any one or multiple combinations selected from magnesite, serpentine and hornblende through high-temperature calcination and sintering; the content of magnesium oxide in the magnesium material is greater than or equal to 85 wt%; the silicon material is one or multiple combinations selected from quartz sand and fumed silica; the content of silicon dioxide in the silicon material is greater than or equal to 92 wt%; the expansion inhibitor is one or multiple combinations selected from sodium citrate, tartaric acid and ethylenediamine tetraacetic acid disodium salt; the calcium material comprises calcium oxide and semi-hydrated gypsum; the content of calcium oxide is 0-45 wt%; the content of semi-hydrated gypsum is 55-100 wt%. When the cement expansion agent is used in a high-temperature oil well cement paste environment, the effect onset time of expansion of oil well cement is moderate, so that microgaps caused by shrinkage after cement paste solidification can be effectively filled up.

Description

technical field [0001] The invention relates to a composite cement expansion agent and a preparation method thereof, in particular to a cement expansion agent suitable for high-temperature environments and a preparation method thereof. Background technique [0002] Ordinary cement will shrink in volume after hardening. The shrinkage of cement paste is divided into plastic shrinkage and hardened body shrinkage. After curing for 120 hours, the shrinkage of cement paste generally exceeds 5%. Volume shrinkage is a fatal flaw in the application of oil well cement in high temperature and high pressure environments. The volume shrinkage of the cement paste prevents the cement sheath from being bonded well with the casing and the formation, and the cement sheath’s cementation quality cannot be guaranteed. In severe cases, micro-gap may be formed, causing formation fluid channeling. Studies have shown that gas channeling can occur if there is a micro-gap of 0.01 mm in the interface ...

AI Technical Summary

Problems solved by technology

[0009] Aiming at the problem in the prior art that there is no oil well cement expansion agent suitable for high-temperature environment, the present invention provides a cement expansion agent suitable for high-temperature environment and its preparation method. When the expansion agent is used in high-temperature cement slurry environment, it can The effective time is moderate, and there is a suitable amount of cement hardening expansion, which can effectively compensate for the micro-gap produced by the shrinkage of the cement slurry after curing.

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