Weak organic acid as gelation retarder for crosslinkable polymer compositions

A method for blocking the permeability of a portion of a subterranean formation penetrated by a wellbore, the method comprising the steps of:

• (a) selecting the portion of the subterranean formation to be treated;
• (b) selecting estimated treatment conditions, wherein the estimated treatment conditions comprise temperature over a treatment time;
• (c) forming a treatment fluid that is a crosslinkable polymer composition comprising:
• (i) a water-soluble polymer, wherein the water-soluble polymer comprises a polymer of at least one non-acidic ethylenically unsaturated polar monomer;
• (ii) a polymeric organic crosslinker comprising amine groups, wherein the organic crosslinker is capable of crosslinking the water-soluble polymer;
• (iii) a weak organic acid, wherein the weak organic acid is a Bronsted acid and wherein the weak organic acid is a separate chemical from the water-soluble polymer and the crosslinker;
• and
• (iv) water;
• (d) selecting the water-soluble polymer, the crosslinker, the weak organic acid, and the water, and the proportions thereof, such that a gelation time of the treatment fluid is at least 1 hour when tested under the estimated treatment conditions;
• and
• (e) injecting the treatment fluid through the wellbore into the portion of the subterranean formation.