Patent Number: 8,875,788

Title: Low temperature inductive heating of subsurface formations

Abstract: Electrical current flow is induced in a ferromagnetic conductor providing time-varying electrical current at a first frequency to an electrical conductor located in a formation. The ferromagnetic conductor at least partially surrounds and at least partially extends lengthwise around the electrical conductor. The ferromagnetic conductor resistively heats up to a first temperature of at most about 300.degree. C. Water in the formation is vaporized with heat at the first temperature. Subsequently, time-varying electrical current at a second frequency is provided to the elongated electrical conductor to induce electrical current flow at the second frequency such that the ferromagnetic conductor resistively heats up to a second temperature above about 300.degree. C. Heat transfers from the ferromagnetic conductor at the second temperature to at least a part of the formation to mobilize at least some hydrocarbons in the part of the formation.

Inventors: Nguyen; Scott Vinh (Houston, TX), Fowler; Thomas David (Houston, TX)

Assignee: Shell Oil Company

International Classification: E21B 36/00 (20060101); E21B 43/24 (20060101)

Expiration Date: 2019-11-04 0:00:00