Effect of calcium chloride on thickening and rheological properties of a self-thickening acid

The crosslinked polymer acid solution relies on a crosslinking agent to form a high-viscosity gel under the condition of weak hydrochloric acid concentration (pH value of about 2–4), and it is difficult to form a high-viscosity gel at high hydrochloric acid concentration. In this work, calcium chloride was investigated as a promoter to enhance the thickening and rheological ability of a self-thickening agent, at high temperature and high concentrations of hydrogen chloride. The results demonstrated that 10 wt.% of calcium chloride can greatly increase the viscosity of a self-thickening acid in the range of high concentration acid (15–10wt.% of hydrogen chloride), which is conducive to the early diversion of the acid solution and better realizes the deep acidification of low permeability formation. Thus, this study provides a novel perspective for developing new self-diverting agents.