Method and apparatus for combating encroachment by in situ treated formations
First Claim
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1. In radio frequency heating of oil shale or tar sand formations in situ wherein a central conductor and a coaxial shield are employed down hole,a method of combating the encroachment of said heated formation, comprisingapplying relative motion to said central conductor periodically for removing said encroaching formation.
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Abstract
A method and apparatus is applicable to in situ heating of oil shale or tar sand. The heating is by radio frequency that is applied down hole by a central conductor that extends beyond a coaxial shielding conductor to form the antenna or applicator. Encroachment by the heated formation is overcome by applying motion to the central conductor to remove encroaching formations.
369 Citations
12 Claims
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1. In radio frequency heating of oil shale or tar sand formations in situ wherein a central conductor and a coaxial shield are employed down hole,
a method of combating the encroachment of said heated formation, comprising applying relative motion to said central conductor periodically for removing said encroaching formation.
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5. In radio frequency heating of oil shale or tar sand formations in situ, in combination with
an applicator for electromagnetic propagation of radio frequency energy into said formation, said applicator comprising a central conductor extending a predetermined distance beyond the end of a coaxial shielding conductor, and a radio frequency generator for supplying said radio frequency energy to said applicator, the improvement comprising means associated with said central conductor for moving it relative to said formation whereby encroachment by said formation may be prevented.
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12. In radio frequency heating of oil shale or tar sand formations in situ, in combination with
an applicator for electromagentic propagation of radio frequency energy into said formation, said applicator comprising a central steel pipe extending a predetermined distance beyond the end of a concentric steel pipe shielding conductor, and a radio frequency generator connected to said central steel pipe and to said concentric steel pipe for supplying said radio frequency to said applicator, the improvement comprising first annular electrically insulating means attached to the inside of said concentric steel pipe, second annular means integrally attached to the outside of said central steel pipe, and hydraulic cylinder and piston means interconnecting said first and second annular means for moving said central steel pipe vertically relative to said concentric steel pipe.
Specification