To Improve The Quality Of Interface Cementation Solidification Segregation System Research

In the cementing operation, drilling fluid and cement slurry will cause pollution of different levels when direct contract with each other, which affect displacement efficiency and lead interface cementation quality decline. Spacer fluid can effectively solve the pollution problem of drilling fluid and cement slurry, flush drilling mud and filter cake, improve the efficiency of displacement, but the well wall and the casing wall still remain part of the drilling fluid, spacer liquid and filter cake unable to solidify, which make the interface of well wall-cement ring-casing wall exist unable solidification layer, lead to the ring empty and the gap of existence, seriously influence interface cementing quality. In view of the above questions, this paper explored and researched a kind of spacer fluid system that can achieve the function in isolation and self-solidification. The goal is to solve the contact pollution problem, but also can solidify existed drilling fluid and filter cake of annulus space.According to the engineering application requirements of solidified spacer fluid, this paper chooses isolation agent GYW-301and bentonite as suspension stabilizer which have been widely applied in well fields, and prepared base fluid of spacer fluid, chooses slag as solidification agent, and investigate the impacts of the slag solidification effects through the different activation agent and dosage, final ascertained JHQ, JHT and GSN as activation agent of spacer fluid, and chooses HX-31L as retarder. Through the indoor study results showing:the solidified spacer fluid can ensure slurry with good suspension stability in using of GYW-301and bentonite; the solidified spacer fluid has high compressive strength on the effect of JHQ, JHT and GSN.From the point of view of material science, experiment investigated the impacts of the slag solidification effect through slag components, summed up the role of the different slag components and suitable content, and considered it as the measure to choose the high quality slag. Through the density regulator regulating the density of solidified spacer fluid, the results showed solidified spacer fluid system is adjustable in1.3g/cm3～2.4g/cm3density range, has good suspension stability, the rheological property can be regulated, the fluidity can control between19and23cm, thickening time can be regulated, the compressive strength can reach8Mpa after24hours, break through the traditional characteristics that spacer liquid can’t solidify.At the same time, this system had good compatibility with drilling fluid and cement slurry, solved the contact pollution problem, and also solidified remain part of the drilling fluid and filter cake, realized overall solidification with drilling fluid and the cement slurry, the whole compressive strength can reach more than8Mpa after48hours. This technology improves the safety of cementing operation, weakened the replacement mechanism and replacement efficiency, made the interface of casing wall-cement ring-well wall solidify together, improved the cementing quality of the interface. It has wide application prospect.