Slightly-expanded oil well cement

Abstract

The invention discloses slightly-expanded oil well cement, belonging to the technical field of well cementing and cementing for oil and gas wells. The well cementing cement comprises the following raw materials in parts by weight: 50 to 80 parts of gel material, 20 to 40 parts of active materials, 0.5 to 3 parts of magnesia expanding agent, 0.1 to 8 parts of alkaline activator, and 2 to 5 parts of stabilizing material; the magnesia expanding agent is light calcined magnesia powder. The slightly-expanded oil well cement disclosed by the invention is mainly used for solving the problem that the expansion effect of expanding cement is poor to influence the early strength in the prior art and has the advantages of good expansion properties in the early, medium and later stages of cement hydration.

Description

technical field [0001] The invention relates to a micro-expansion oil well cement, which belongs to the technical field of oil and gas well cementing and cementing. Background technique [0002] The high water loss and volume shrinkage in the cement hydration process of oil wells are the main reasons for the poor bonding quality of the cement annulus interface, the channeling of oil, gas and water in the well, and the pollution of the oil layer. This is also a cementing technology that has not yet been well resolved. problem. The volume shrinkage of oil well cement slurry when solidified under high temperature and high pressure is 2.6% to 5.0% of the total volume of the cement slurry, and more than 95% of the shrinkage occurs after the final setting of the cement slurry. The volume shrinkage of the cement slurry in the plastic state will reduce the pore pressure of the cement slurry column (gelation weight loss), resulting in oil, gas, and water channeling; the volume shrin...

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Problems solved by technology

[0006] The present invention aims to provide a new micro-expansion oil well cement, which solves the problems in the prior art that the expansion effect is not good, the corrosion resistance is poor, and the early strength of the cement is affected after the expansion agent is added.

The present invention solves the problems of not obvious expansion of expansive cement at high temperature, slow expansion speed at low temperature and poor early strength of cement by adding active material, alkaline activator, magnesium oxide expansion agent and specific proportion adjustment. The cement has a good expansion effect in the early, middle and late stages of hydration

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