Patent ID: 8027571
Filing Date: 2011-09-27
Classification: C07C,E21B,Y10T

Abstract:
1. A system for heating a subsurface formation, comprising: a plurality of elongated heaters located in a plurality of openings in the formation, at least two of the heaters being substantially parallel to each other for at least a portion of the lengths of the heaters, wherein at least one opening comprises a substantially u-shaped opening; at least two of the heaters having first end portions in a first region of the formation and second end portions in a second region of the formation; and a source of time-varying current configured to apply time-varying current to at least two of the heaters, wherein the first end portions of at least two heaters are configured to have substantially the same voltage applied to them, and the second end portions of at least two heaters are configured to have substantially the same voltage applied to them, and wherein the source of time-varying current comprises an electrically isolated, single-phase transformer.