Preparation and properties of a double quaternary ammonium copolymer used in acid fracturing

Abstract

Triethylamine (TEA), 1, 4-dibromobutane (C4H8Br2) and N, N-dimethylaminopropyl acrylamide (DMAPAA) were selected to synthesize a double quaternary ammonium cationic monomer (TDD). TDD, acrylamide (AM), 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and acrylic acid (AA) were used to create a quadripolymer (PAAT) that was characterized by FT-IR and 1H NMR. Following that, the basic performance of thickened acid was assessed. The results revealed that PAAT outperformed PAA (copolymerized by AM, AMPS and AA) in terms of acid solubility, thickening performance, temperature resistance and shear resistance. Furthermore, this crosslinked acid containing PAAT was subjected to a series of performance evaluations. The viscosity of the crosslinked acid could be kept at 67 mPa·s at 160°C after 90 min and the weight loss rate of crosslinked acid in acid-rock reaction at 60 min was 23%, indicating the temperature resistance and retarder performance of the crosslinked acid solution was significantly better than that of the thickening acid and the blank acid. A scanning electron microscopy experiment revealed that crosslinked acid has good corrosion ability and low damage to the reservoir. The above experimental results indicated that the thickener PAAT has a promising future application in acid fracturing of high-temperature and high-mineralization carbonate reservoirs.

Keywords

• Diquaternary ammonium
• Thickening agent
• Crosslinked acid
• Cationic monomer
• Retardation