Salty flushing fluid for well cementation and preparation method thereof

Abstract

The invention discloses a salty flushing fluid for well cementation. The formula of the salty flushing fluid comprises 100 parts of water, 10-36 parts of sodium chloride, 1-3 parts of sodium carbonate, 1-10 parts of betaine-type amphoteric surfactant and 0.1-5 parts of sodium lignin sulfonate; the invention further discloses a preparation method of the salty flushing fluid for well cementation. The method comprises the following steps: completely dissolving sodium chloride, sodium carbonate and sodium lignin sulfonate in water, and then adding the betaine-type amphoteric surfactant, further stirring for 10-20min to obtain the salty flushing fluid for well cementation. The salty flushing fluid for well cementation is used for reducing or preventing the dissolving to an salt gypsum bed when the well cementation is performed on the salt gypsum bed, and avoiding the hole-wall collapsing caused when the salt gypsum bed is excessively dissolved by the flushing fluid, and a sleeve wall can be effectively flushed, the interface bonding strength of the cement slurry and the sleeve is improved, the well cementation quality is improved, and the salty flushing fluid is suitable for oil-based drilling fluid or water-based drilling fluid.

Description

technical field [0001] The invention belongs to the technical field of petroleum drilling, in particular to a salt-containing flushing fluid for well cementing and a preparation method thereof. Background technique [0002] In drilling operations, the long-term circulation of mud will form a thicker virtual mud cake on the well wall and casing. No cementation will seriously affect the cementing quality. Therefore, in the cementing operation, it is necessary to inject a certain amount of flushing fluid containing surfactant before cementing, dilute and remove the virtual mud cake, improve the affinity of the two interfaces, and improve the bonding quality between the cement slurry and the two interfaces , to improve the quality of cementing. In response to this situation, major domestic oil fields have developed a series of flushing fluids, which are used in cementing site construction, effectively improving the cementing quality. [0003] However, with the development of ...

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Problems solved by technology

However, at present, the surfactants used in the salt paste layer in the flushing solution developed in China have poor salt resistance and poor solubility under high-concentration salt conditions, that is, sufficient surfactant cannot be dissolved in high-concentration salt solutions. The agent causes the flushing effect of the flushing solution to deteriorate

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