Self‐healing behaviors of sulfobetaine polyacrylamide/chromium gel decided by viscosity and chemical compositions

Abstract

The self‐healing behaviors of sulfobetaine amphoteric polyacrylamide/chromium (SPAM/Cr) gel are investigated. The role of chemical composition, including different types of polyacrylamide, acid, and sodium sulfate, in the gel synthesis process as well as the gel's self‐healing ability are studied and compared. It is found that the chemical structure with electrostatic discharge repulsion and hydrophobic interaction of amphoteric polyacrylamide play the key roles in the gelation and self‐healing processes. Furthermore, lactic acid cannot only adjust the pH value of the system, but also help to form organic chromium, which can coordinate with the COO group to form the crosslinked gel. The concentration of sodium sulfate can affect self‐healing behaviors via electric charge as well. A best concentration range of 220–1600 mg/L is found to provide the maximum self‐healing ability in the SPAM/Cr gel at 45 °C for 72 h. The oil field experimental results for the S5‐10‐P50 well group show that the viscosity recovery rate of the SPAM/Cr gel is greater than 66% after 60 days, and the average starting pressure increases about 1–3 MPa after profile control. The results demonstrate that self‐healing SPAM/Cr gel is a type of high‐efficiency gel that can be used for depth water plugging and profile control in oil fields. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46991.