Research and Development of Leakage Plugging Cement Slurry System Based on a New Thixotropic Agent
Complex formations such as natural large fracture holes,weak mud shale,and narrow safety density windows cause malignant well leakage problems and low success rate of plugging,which has become one of the important technical problems restricting the quality and efficiency of drilling projects.Based on the action mechanism of thixotropic agent,a new type of low viscosity thixotropic agent XZ-CBL combining organic and inorganic was developed by graft copolymerization of nano-silica with 3 monomers of 2-acrylamido-2-methylpropanesulfonic acid(AMPS),acrylamide(AM)and dimethyl diallyl ammonium chloride(DMDAAC),and the water loss reducer and retarder were optimized to form a thixotropic plugging cement slurry system.Experimental tests showed that the thixotropic plugging cement slurry system had good fluidity,the initial consistency was as low as 10 Pa·s,and after standing for 10 min,it showed strong thixotropy,and the increase of shutdown consistency was greater than 20 Pa·s,and the shear consistency quickly returned to the consistency before shutdown,which had the characteristics of good pumpability and strong retention.
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