Method for preparing foamed cement slurry

Abstract

The invention discloses a method for controlling a mixing ratio of foam and cement slurry in preparation of formed cement slurry. The method comprises the steps of: i), providing a foam and cement slurry mixing device, wherein the device comprises foamed cement slurry equipment, a first volume flow meter, cement slurry mixing equipment and foam equipment of which the pressure is controlled by a pressure gauge; ii), controlling a first flow F1 of the foam cement slurry flowing into an oil well by using the first volume flow meter, and controlling a second flow F2 of the cement slurry flowing into the foamed cement slurry equipment by using the second volume flow meter; and iii), measuring slurry density Rho 2, fixing the first flow F1, and adjusting the density of the foamed cement slurry according to a formula that Rho 1 is equal to Rho 2 * F2 / F1 until the Rho 1 reaches a target value, wherein the pressure in a foam tank is constant.

Description

Technical field

[0001] The invention relates to a method and device for preparing foam cement slurry and its application, in particular to a method for controlling the mixing ratio of foam and cement slurry used in on-site cementing construction, and belongs to the field of low-density cementing in oil fields. Background technique

[0002] Foamed cement refers to mixing a certain amount of foam into conventional cement slurry to form a solid, liquid, and gas three-phase multi-phase system with high dispersibility. Foam cement cementing is mainly to reduce the density of cement slurry, thereby reducing the liquid column pressure of the cement slurry section in the annulus, to solve the problem of cementing leakage in the low-pressure and easy-to-leak oil layer, and to protect the oil layer. Although foamed cement slurries have been used in the construction industry more than 50 years ago, the foamed cement slurries for oil wells were first proposed by Aldrich and Mitchell in the U...

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