“…To solve the above problems, common method is to inject selective plugging agents into high-permeability channels such as fractures [ 2 , 3 ]. Phenolic gel is one of the most commonly used plugging agents, the use of which is mainly divided into two methods: one is to make gelants by adding phenol and aldehyde solutions to the polymer solutions [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]; the other is to directly add a water-soluble phenolic resin solution into the polymer solutions [ 2 , 3 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ].…”