Research And Performance Evaluation Of Low Temperature High Early Strength Addictive For Oil Well Cement

Low temperature early strength slurry is a kind of slurry to meet the needs of cementing in low temperature. According to the problems in drilling process in Daqing Oil Field in winter, such as low temperature when cementing surface casing pipe, strength develops slow, long waiting on cement and so on. Researched a new kind of early strength additive named QZ-1, it is composed through certain proportion by active silica flour, solid hydramine and anionic polymer. It can enhance the speed of hydration greatly, accelerate the generation of cement's early strength. This additive didn't embody chloride ion, can overcome the problems of casing corrosion caused by traditional additive. At the same time, the active silica flour can join the cement's hydration reaction, makes the cement's volume has a little expansion; the solid hydramine can united with cement grain and water numerator through hydrogen bond and van der Waals force, adsorbed by cement grains, deepen the hydration. The links of the anionic polymer have plenty of sticking groups (hydroxyl and amide group) and hydration groups (carboxyl group), they can adsorbed on cement grains, enhance the slurry's viscosity. Analysis the influences of QZ-1 to the slurry's behavior through experiments, includes compressive resistance, thickening time, rheological property, filter loss, contraction and expansion ability and consolidation strength; gets the conclusions: QZ-1 has remarkably early strength effect, 20℃,adds 2%, maintenance 12h, the compressive resistance can reaches 3.6MPa, meets the need of second spudding; the thicken time can be adjusted, the curve of viscosify has right angle effert; the ligancy with some common fluid loss control agents is good; with the increase of QZ-1's add, the shrinking of cement becomes smaller, the consolidation strength becomes bigger. At last, with the help of the scanning electron microscope, research the microscopical feature of cement's hydration process, find the cement'hydration mechanism and the additive's early strength mechanism.