Thixotropic Cement Slurry Research

Thixotropic cement of cementing oil and gas wells is that the thixotropic agent is added to the ordinary portland cement, so that in the process of mixing and replacement fluid is thin, after pumping stopped, the rapid formation of a rigid (capable of self-support) condensate structure special cement, primarily used to prevent gas channeling, plugging and squeeze cement job.Gas channeling of Cementing operations generated is mainly due to the liquid column pressure and formation pressure imbalance, and often occurs in the cement from the liquid to solid transition period. the use of a thixotropic cement, when it enters the transition state since gelation increases rapidly, the cement grout fall slowly, effective static pressure acting on the Stratum reduced, and because of the further development of gel strength, also to a considerable extent prevent mechanical deformation and generation of the liquid column bubble. Therefore, except for plugging operations, the thixotropic cement also can be used to prevent gas channeling. Thixotropic cement slurry cementing technology has been widely used in the field of oil well cementing for many years, and gets more and more attention because of it’s good thixotropy.After a lot of research on the basis of the literature, this paper studies the thixotropic of cement slurry with the use of Thixotropic ring and Gel strength. Based on preliminary work in laboratory, this paper chose A, B, C three substances as the basic recipe of thixotropic agents,adding the compound of A, B, C to oil well cement, and developed conventional density thixotropic cement slurry system, low density thixotropic cement slurry system and ultra-low density thixotropic cement slurry system using orthogonal experimental method; experimental results show that the three cement slurry has good thixotropy with the use of anti-channeling experimental apparatus developed; puts forward consistency increment as an new index to evaluate thixotropic of cement slurry.