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In this paper, the nano terpolymer of acrylamide (AM), 2-acrylamido-2-methyl -1-propane sulfonic acid (AMPS), N-vinyl-pyrrolidone (NVP) was synthesized by free radical polymerization in water solution. The addition of ethanol was used to control molecular weight of terpolymer. The plugging properties and mechanism of terpolymer were studied. The characterization and properties of nano terpolymer were studied by Fourier transform infrared spectroscopy, particle size analyzer, transmission electron microscopy. The results indicated that the structure of terpolymer was consistent with design. It was nano material in water and kept on nanoscale stable in drilling fluid. The filtration property of terpolymer was studied by drilling fluid filter press and the results indicated that the filtration property of terpolymer was equal to fluid loss agent. Nevertheless, the addition of inorganic nanoparticles resulted in high amount of filtration volume in the same conditions because of extensive agglomeration of inorganic nanoparticles. The stability of nano materials in solution was requirement to plug nanopores. The resistance properties to salinity, calcium and high temperature were studied, and the results showed that the properties were better than PAC which is widely used in oil flied as fluid loss agent. The plugging properties of terpolymer were studied by specific surface and porosity physical adsorption instrument (BET) and the membrane efficiency tester. BET results showed that the surface area of natural rock reduced after treated with terpolymer, indicating terpolymer entered into nanopores of shale because of the adsorption in the surface of shale. In study of the membrane efficiency test, the addition of terpolymer resulted in significantly reducing of shale permeability. It was further presented that nanopores of shale were plugged by terpolymer. |
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