Oil well cement-injection pad fluid admixture and preparation method

Abstract

The invention provides a lead admixture for oil well cement, which is used in cementing operation. The invention is characterized in that: the invention comprises microcapsule emulsified tackifier and diluting, grinding, antigelling agent, the weight percent of the two components is 40 to 50 percent:50 to 60 percent, wherein, the weight percent of the composition of microcapsule emulsified tackifier is as follows: 30 to 40 percent of Sorbitan Monostearate emulsifying agent, 60 to 70 percent of sodium carboxymethylcellulose; and the weight percent of the composition of the diluting, grinding and antigelling agent is as follows: 30 to 40 percent of sulfonated tannin, 30 to 40 percent of fine silica powder, 10 to 25 percent of sodium sulfate, and 10 to 25 percent of sodium carbonate. The invention has the advantages that: the lead compounded by the lead admixture for oil well cement has good slurrycompatibility with drilling fluid and oil well grout. And flushing fluid, weighted spacer fluid, viscoelastic spacer fluid and displacement fluid can be prepared by compounding with the lead admixture for oil well cement. The lead admixture for oil well cement has the characteristic of high dissolution rate and easy field compounding.

Description

technical field [0001] The invention relates to the technical field of oil, natural gas and water well cementing, in particular to a cementing prefluid admixture for well cementing, and is a preparation method capable of preparing flushing fluid, spacer fluid and plugging fluid admixture for cementing and cementing slurry . Background technique [0002] Before oil and gas well cementing and injecting slurry, in order to isolate the cement slurry from the drilling fluid and improve the displacement efficiency, a liquid needs to be injected between the cement slurry and the drilling fluid, and the injected liquid is called the slurry pre-fluid. Why use grout pre-fluid? Because the cement slurry phase is saturated with C a (OH) 2 Once the solution is mixed with the drilling fluid, the clay component in the drilling fluid will undergo calcium invasion to form a viscous flocculation substance, making the mixture a jelly with extremely poor fluidity or no flow; in addition, the...

AI Technical Summary

Problems solved by technology

[0005] Sodium silicate type pre-fluid, the pre-fluid has a certain viscosity, which can improve the displacement efficiency, but the compatibility with cement slurry is not good, which affects its fluidity

[0006] Dilution prefluid, the prefluid is mainly composed of drilling fluid diluent, which can dilute the drilling fluid and improve the flushing efficiency, but affects the stability of the well wall

[0007] Cellulose-type pre-fluid, which can increase the average density of the liquid column and stabilize the formation, but it is difficult to prepare on-site

[0008] Polymer type prefluid, which can increase the average density of the liquid column, but the cost is high and it is difficult to prepare on site