Development and Performance Evaluation of a High Temperature-Resistant Isolation Membrane Retarded Acid Solution System

In order to solve the problems of high viscosity of acid solution and low pump displacement in acid fracturing stimulation of carbonate reservoirs, the isolation membrane retarder for high temperatures was synthesized by free radical aqueous polymerization with acrylamide (AM), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), and fluorine-containing monomer (ZTA) as monomers. An acid-resistant drag reducer was prepared by inverse emulsion polymerization, with AM, AMPS, and methacryloyloxyethyl trimethylammonium chloride (DMC) as monomers. The results of infrared, thermogravimetric, and X-ray diffraction (XRD) analysis of the isolation membrane retarder and drag reducer showed that they conformed to the molecular structure design, and their thermal decomposition temperatures were 209.13 °C and 243.70 °C, respectively. A retarded acid solution system with a high temperature-resistant isolation membrane was formed through compatibility testing and optimization on the concentration of isolation membrane retarder and acid-resistant drag reducer. The viscosity of the acid solution system was less than 5 mPa·s. In a 20% hydrochloric acid system, the average acid rock reaction rate was 4.31 μmol/(cm²·s) at 140 °C, which was 34.8% lower than the gelled acid system, and a drag reduction rate of the acid solution system (15% hydrochloric acid) was 62.7%. The results showed that the developed retarded acid solution system with high temperature-resistant isolation membrane resulted in good retarding and drag reduction performance and could be used for acid fracturing and acidizing in Tahe Oilfield.