Patent ID: 11926713
Assignee: SAUDI ARABIAN OIL COMPANY
Field: Basic materials chemistry (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A method for monitoring gel integrity in a subterranean formation, the method comprising:
introducing a polymer gel in a non-gelled state into the subterranean formation, the polymer gel comprising:
a polymer gel base material comprising at least water and polymer; and
superparamagnetic nanoparticles having a bimodal size distribution and each having a diameter of less than 100 nm, where:
at least 25 wt. % of the superparamagnetic nanoparticles have diameters in a first size range between a first diameter and a second diameter, where the first diameter is less than the second diameter, and where the difference between the first diameter and the second diameter is 4 nm;

the diameter of the particles in the first size range is measured as the core diameter;
at least 25 wt. % of the superparamagnetic nanoparticles have diameters in a second size range between a third diameter and a fourth diameter, where the third diameter is less than the fourth diameter, and where the difference between the third diameter and the fourth diameter is 8 nm;
the diameter of the particles in the second size range is measured as the hydrodynamic diameter;
the second diameter is less than or equal to the third diameter;

subjecting the polymer gel in the subterranean formation to a magnetic field; and
measuring magnetic susceptibility of the formation at a certain depth, as a function of time.