04793409 is referenced by 129 patents and cites 9 patents.

A method and apparatus for forming an electrically conductive externally insulated casing for an oil well of the type in which the casing carries electrical current to a primary heating electrode positioned downhole, using multiple prefabricated casing segments; each casing segment is a long steel pipe having a female thread coupling on one end and a male thread on the other end. Each segment has an insulator covering, over substantially all of its length, that has a figure of merit (erl)/.DELTA. of no more than 4.times.10.sup.8 so that the shunt impedance of the casing to ground can be kept substantially greater than the spreading resistance of the primary heating electrode. The preferred casing segment insulation is in two layers, including a hard, durarable inner layer subject to water degradation and an outer water-impervious layer usually applied as tape. The uninsulated portions of joints between segments are covered withan insulator cement in the field and then further covered with a water-impervious tape that overlaps the water-impervious layers on two segments.

Title
Method and apparatus for forming an insulated oil well casing
Application Number
7/64063
Publication Number
4793409
Application Date
June 18, 1987
Publication Date
December 27, 1988
Inventor
Vincent R Young
Tulsa
OK, US
Homer L Spencer
Tulsa
OK, US
Joseph O Enk
Lake in the Hills
IL, US
Jack E Bridges
Park Ridge
IL, US
Agent
Kinzer Plyer Dorn McEachran & Jambor
Assignee
ORS Development Corporation
OK, US
IPC
H05B 3/02
F16L 9/14
E21B 36/00
E21B 19/16
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