Insulating liquid for injecting cement in oil well

Abstract

The invention relates to an isolating liquid used in oil well cementing, comprising fresh water, suspension agent, thinner agent and aggravation agent. The invention is characterized in that: the suspension agent is made from hydroxy ethyl cellulose, carboxymethyl cellulose, xanthan and na-bentonite; the thinner agent is made from sodium lignosulphonate, sodium dodecyl benzene sulfonate and alkyl phenol polyoxyethylene ether; the aggravation agent is made from barite, fly ash, limestone and slag. When preparing the isolating liquid, the suspension agent is dissolved in water for one hour, thereafter thinner agent is added. Before cementing, the aggravation agent is added into the solution and mixed evenly. The isolating liquid is characterized by low viscosity, good rheological performance, slow critical velocity and being easy to form turbulent flow, so as to effectively substitute and wash mud, prevent forming mixed slurry of cement slurry and mud. Meanwhile, the invention can be compatible with ordinary cement slurry and mud system, thus diluting and improving cement slurry rheological performance.

Description

technical field

[0001] The invention relates to a spacer fluid for oil well cementing, which can be used to separate mud and cement slurry in well cementing and cementing operations, so as to prevent the mud and cement slurry from contacting and polluting each other. Background technique

[0002] The spacer fluid used in the early days was mainly the solution prepared by cementing admixture, which had good compatibility with the cement slurry system, but the compatibility with the mud was not ideal; in the late 1980s, many oil fields used sodium silicate spacer fluid The system is simple in composition and has a certain degree of viscosity and suspension, but sodium silicate has a coagulation-accelerating effect on cement slurry and is not ideally compatible with many cement slurry systems; in the 1990s, with the requirements for cementing quality It is getting higher and higher, and more attention is paid to the displacement characteristics, suspension characteristics, stab...