Methods for treating a well with a cross-linked water-soluble polymer-complexed metal cation network and an aromatic compound capable of forming a chelating agent to uncross-link the polymer

摘要

Methods are provided for treating a portion of a well. The method according to this aspect comprises the steps of: (A) forming a treatment fluid, the treatment fluid comprising: (i) water; (ii) a water-soluble polymer; (iii) a complexed metal cation that: (a) has a valence state of at least three; and (b) is capable of cross-linking the water-soluble polymer; and (iv) an aromatic compound that is capable of dissolving, melting, or chemically decomposing, dissociating, or reacting, to form a chelating agent, wherein the chelating agent comprising vicinal substituents containing donor heteroatoms, and wherein the chelating agent is capable of chelating the metal cation; and (B) introducing the treatment fluid into the well.

主权项

1. A method for treating a portion of a well, the method comprising the steps of:
(A) forming a treatment fluid, the treatment fluid comprising:
(i) water;(ii) a water-soluble polymer;(iii) a complexed metal cation that:
(a) has a valence state of at least three, wherein the metal cation of the complexed metal cation is selected from the group consisting of Fe(3+), Al(3+), Ti(4+), Zr(4+), Hf(4+), and any combination thereof in any proportion; and(b) is capable of cross-linking the water-soluble polymer; and(iv) an aromatic compound that is capable of dissolving, melting, or chemically decomposing, dissociating, or reacting to form a chelating agent, wherein the chelating agent comprising vicinal substituents containing donor heteroatoms, and wherein the chelating agent is capable of chelating the metal cation; wherein a test fluid consisting essentially of, in the same proportions as in the treatment fluid:
(i) the water;(ii) the water-soluble polymer;(iii) the complexed metal cation; and(iv) the aromatic compound, wherein the aromatic compound is non-encapsulated in the test fluid, is capable of:
(i) increasing from an initial viscosity to a maximum viscosity that is greater than the initial viscosity; and then(ii) decreasing to a decreased viscosity that is less than the maximum viscosity, when tested by heating the test fluid at a constant rate from an initial temperature of 25° C. to at least one elevated temperature in the range of 50° C.-100° C. over the course of 10 minutes and then maintained at that elevated temperature; and (B) introducing the treatment fluid into the well; wherein the chelating agent comprises at least one of the following chemical structures having an aromatic ring and wherein X and Y are vicinal: wherein X and Y each independently is selected from the group consisting of —O—, —COR, —O−A+, —NR1R2, —OR, —COOH, —COO−A+, —C(R)O, —CONR1R2, —CR1R2OH, —CR1R2NH2, —CR1R2—COOH, —CR1R2COOR, —CR1R2COO−A+, —C(R)═NR, —SR, and —S−A+; wherein R, R1, and R2 are independently H, or alkyl groups containing 1-4 carbons; wherein A+ is an alkali metal ion or an ammonium ion; wherein Z can be S, O, or NH; and wherein the aromatic ring is selected from the group consisting of a benzene ring, a pyridine ring, a thiophene ring, a pyrrole ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring.