Copolymer MCJS as a retarder of the acid–rock reaction speed for the stimulation of deep carbonate reservoirs

The fast reaction rate between hydrochloric acid and carbonates causes the most acid consumption near the wells, and the acid cannot penetrate the deeper places of the carbonate reservoir; this limits the application of acidizing modifications for the reservoir. In this study, we chose acrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), allyl alcohol polyoxyethylene ether (APEG), and N-dimethyl-N-vinyl nonadecan-1-aminium chloride (DMAAC-18) to synthesize a quadripolymer (MCJS) that could reduce the reaction rate mentioned previously. The molecular structure of MCJS was characterized by Fourier transform infrared and ¹H-NMR spectroscopy. The molecular weight and molecular weight distribution of MCJS was determined by gel permeation chromatography. Carbonate rock was analyzed by X-ray diffraction and energy-dispersive X-ray spectroscopy. The retarding properties of the acid mixed with MCJS (MCJS acid) were investigated, and the resulting reaction rate between the acid and carbonate decreased obviously, even at a low viscosity. Scanning electron microscopy and core flood experiments showed that the MCJS could be adsorbed on the carbonate rock surface and form a hydrated film that delayed the reaction. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41471.