Effect of non-crosslinked polymer (ADDA) on acid-rock reactions: synthesis and thickening laws

Studying the thickening mechanism of non-crosslinked self-thickening polymer (ADDA) is of great significance for plugging high permeability channel and reducing reservoir heterogeneity. ADDA was synthesized from acrylamide, octadecyl dimethyl ammonium chloride, N-(3-(dimethylamino)propyl)methacrylamide and 4-acryloylmorpholine. The changes of apparent viscosity and hydrodynamic radius of ADDA acid solution were studied by simulating the acid rock reaction process. The hydrophobic joint strength and hydrophobic joint structure in the acid rock reaction process of ADDA acid solution were characterized by UV spectrum and environmental scanning electron microscopy (ESEM), and the self-thickening mechanism of ADDA acid solution in the acid rock reaction process was obtained. The results show that the apparent viscosity of ADDA acid solution increases monotonically with the acid rock reaction process, showing good self-thickening ability and high temperature resistance. Compared with the traditional in-situ crosslinking acid, ADDA acid solution avoids the secondary damage caused by the addition of crosslinking agent. Calcium chloride produced in the reaction process increases the polarity of the solution, is conducive to the intermolecular binding of ADDA polymer, and increase the apparent viscosity macroscopically. With the progress of the reaction, the hydrophobic combination strength of acid solution increased, and the hydrophobic combination between polymer molecules formed a three-dimensional network structure.