Additive for well cementing cement mortar, and preparation and application methods thereof

Abstract

The invention provides an additive for well cementing cement mortar and preparation and application methods thereof, relating to the field of well cementation with oil well cement. The additive for oil well cement is mainly prepared by uniformly mixing 35 to 65 wt% of modified resin, 3 to 35 wt% of calcium carbonate, 5 to 25 wt% of active silica, 2 to 15 wt% of alkylsilane and the like. When the additive is added into a well cementing cement mortar system according to a weight ratio of cement to the additive of 100: 2-10, the additive promotes self-healing of cracks or micro-annulus of a cement sheath caused by various factors when the well cementing cement mortar system comes across water, compressive strength of the cement sheath is improved, and permeability of the cement sheath is reduced. Set cement with the additive has expansibility, cementation strength of a well cementing interface and zone isolation capacity of a cement sheath column are both improved, and the set cement is applicable to different temperatures in well cementation environments with severe properties.

Description

technical field [0001] The invention relates to a self-healing cementing cement slurry admixture in the field of oilfield chemical additives, and a preparation method and an application method of the admixture. Background technique [0002] The ability of cement slurry to isolate oil and gas wells is an important indicator of cementing quality and oilfield life. Even if the layer of cement sheath isolation is suitable, it can initially provide a complete layer isolation, but in the subsequent drilling or oil and gas production process, such as tripping, shrinkage of cement stone, perforation, pressure holding, fracturing, acidizing Factors such as workover, formation creep and other factors may cause cracks or micro-annulus in the annular cement sheath, and interlayer channeling, resulting in irreversible loss and waste of oil and gas resources, and also poses a huge threat to the underground environment. However, refilling cement, squeezing cement or secondary cementing in...

AI Technical Summary

Problems solved by technology

Even if the layer of cement sheath isolation is suitable, it can initially provide a complete layer isolation, but in the subsequent drilling or oil and gas production process, such as tripping, shrinkage of cement stone, perforation, pressure holding, fracturing, acidizing Factors such as workover, formation creep and other factors may cause cracks or micro-annulus in the annular cement sheath, and interlayer channeling, resulting in irreversible loss and waste of oil and gas resources, and also poses a huge threat to the underground environment

However, cement injection, cement extrusion or secondary cementing will cost a lot of money in the later stage, and these measures have great safety risks

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