Application method of cement additive

Abstract

The invention discloses an application method for a cement additive, which includes the following steps: (a) 4-8% weighted acrylamide, 2-4% weighted cross linker, 1-3.5% weighted evocating agent, 1-4%weighted intensifier and residual water is cross-linked under normal pressure and at the temperature of 75-90 DEG C, gel is formed, dried and crashed to obtain the cement additive; (b) the prepared cement additive is added to cement slurry, wherein, 1.5-3 parts by weight of cement additive is added into 100 parts by weight of cement slurry, and 2 parts by weight of cement additive is preferred. By adopting the application method of the invention and applying the cement additive to the cement system of oil field cementing, the phenomenon of gas channeling is prevented and the cementing qualityis improved; the qualification rate of the cementing quality is improved from the original 45% to more than 94%.

Description

technical field [0001] The invention relates to an application method of cement additives, in particular to an application method of cement additives in oil field cementing. Background technique [0002] In view of shallow depth of reservoir, high oil-gas ratio, a large amount of natural gas dissolved in underground crude oil, low viscosity and low density of crude oil, when the oil layer is opened, when the pressure drops below the saturation pressure, the crude oil in the formation will be seriously degassed. During the process, the released gas escapes into the cement stone matrix, or enters the gap between the cement and the casing or the cement and the well wall, causing interlayer interleaving or even to the wellhead, which eventually leads to low cement cement bond strength or interlayer channeling , Seriously affecting the quality of cementing, even if remedial measures such as cement extrusion are adopted, it is difficult to be effective, and it will adversely affec...

AI Technical Summary

Problems solved by technology

[0002] In view of shallow depth of reservoir, high oil-gas ratio, a large amount of natural gas dissolved in underground crude oil, low viscosity and low density of crude oil, when the oil layer is opened, when the pressure drops below the saturation pressure, the crude oil in the formation will be seriously degassed. During the process, the released gas escapes into the cement stone matrix, or enters the gap between the cement and the casing or the cement and the well wall, causing interlayer interleaving or even to the wellhead, which eventually leads to low cement cement bond strength or interlayer channeling , which seriously affects the quality of cementing. Even if remedial measures such as cement squeezing are adopted, it is difficult to be effective, and it will have adverse effects on subsequent oilfield operations such as water injection, acid fracturing, and layered mining, and even cannot be carried out.

In addition, due to the large difference between the oil layers, the high-pressure layer and the low-pressure layer exist at the same time. If the density of the cement slurry is increased to prevent gas channeling, it will cause pollution to the low-pressure layer, or even pressure leakage. Gas channeling affects the quality of cementing. In severe cases, formation oil, gas and water may channel to the surface