Study On Synthesis And Application Of Cationic Polyacrylate Shale Inhibitor

With the action of potassium peroxydisulfate (KPS) and deflocculant, a series of P(AM/DMC/MMA/AA) emulsion were successfully prepared by surfactant-free emulsion polymerization. They were prepared by the reaction of acrylamide(AM), methacryloyl oxygen ethyl three methyl ammonium chloride(DMC), methyl methacrylate(MMA) and acrylic acid(AA) as raw materials. The optimal synthe-sizing process of emulsion was discussed and determined by studying emulsion appearance, viscosity, stability and effects of monomers content on shale recovery and expansion ratio. The structures of the final formed copolymers were characterized by Fourier transform spectroscopy (FTIR) and Nuclear magnetic resonance(NMR). The thermal stability and crystallinity of P(AM/DMC/MMA/AA) were analyzed through Thermogravimetric analysis (TGA) and X-ray diffraction spectrogram(XRD). The rheological behaviors, particle size and zeta potential of P(AM/DMC/MMA/AA) emulsion were studied by Rheometer, Dynamic light scattering (DLS) and Zeta potentiometer. The application of P(AM/DMC/MMA/AA) emulsion as shale inhibitor agent was also studied. The main results were shown as follows:(1) The optimum reaction condition was described as below:the soap-free emulsion polymerization was applied in this study; the shale inhibitor agent have good property when AA=4%, DMC=10%, MMA=8%～9%. Adding deionized water, AM, AA, DMC and MMA, and stir them to dissolve with the action of catalyst and deflocculant. The reaction was polymerized for3h in70℃. Thus, the P(AM/DMC/MMA/AA) emulsion was obtained with the solid content of15%.(2) The structure of the product was analyzed by IR and ’HNMR and the results demonstrated that P(AM/DMC/MMA/AA) was the expected product.(3) The thermal stability of P(AM/DMC/MMA/AA) membrane had slightly decreased with AA or MMA addition. The average diameter of the particles first became smaller and then greater with AA addition, and the zeta potential have decreased. The average diameter of the particles and zeta potential presented the opposite tendency with DMC increasing. The average diameter of the particles first became greater and then smaller with MMA addition, and the emulsions exhibited a newtonian behavior at first and then Non-newtonian behavior, and they are Shown a certain degree of pseudoplastic and thixotropic, and they are endowed with the apparent viscosity decreases with increasing the shear rate.(4) The shale recovery and expansion ratio was up to25.4%and11.4%by1%P(AM/DMC/MMA/AA) emulsion. P (AM/DMC/MMA/AA) emulsions have good inhibitor and flocculation performance from the photos of the core immersion test and flocculation experiments P (AM/DMC/MMA/AA) emulsions have good compatibility with different types and concentrations of salt.The above studies have shown that the synthetic shale inhibitor is the target product, and has good ability to shale inhibition, can significantly inhibit shale hydration expansion. The product has good compatibility with inorganic salts. This is a new shale inhibitor agent can significantly improve the recovery rate of shale and to reduce the swelling of the shale.