| 摘要 |
The invention relates to an A.C. electrical heating system for heating a fluid reservoir in the vicinity of a mineral fluid well, utilizing A.C. electrical power in a range of 25 to 1000 HZ. The well comprises a borehole extending down through an overburden and through a subterranean fluid (oil) reservoir; the well includes an upper electrically conductive casing extending around the borehole in the overburden, at least one electrically conductive heating electrode located in the reservoir, and an electrically insulating casing between the upper casing and the heating electrode. The heating system comprises an electrical power cable extending down through the conductive upper casing to the heating electrode to supply electrical power to the heating electrode. The electrical power cable comprises at least two electrical conductors, isolated from each other, and an armor sheath of magnetic material encompassing the conductors, the conductors being electrically terminated at the heating electrode. There is a net vertical current of approximately zero in the conductors so that eddy current and skin effect losses in the armor sheath are minimized.
|
