Method and Apparatus for Mitigation of Radio Frequency Electric Field Peaking in Controlled Heat Processing of Hydrocarbonaceous Formations In Situ
Bridges, Jack E.
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The effects of radio frequency electric field peaking in the earth formations surrounding a conductor excited by radio frequency energy in the controlled in situ heat processing of hydrocarbonaceous earth formations are mitigated by providing an inert buffer region around the conductor to which radio frequency electromagnetic energy is supplied to produce an electric field within the earth formations. A portion of the earth formations is removed to accommodate insertion of the conductor at a desired location in the earth formations and to provide a buffer region between the conductor and the surrounding earth formations. The conductor is supported at the desired location in spaced relationship to the surrounding earth formations, the buffer region encompassing the principal region of the electric field enhancement region around the conductor where the probability of breakdown in the earth formations over the period of application of the radio frequency energy would be above a tolerable level. The buffer region is filled with dielectric material having an electric field breakdown level greater than that of the surrounding earth formation medium such that the probability of breakdown in the buffer region over the period of application of the radio frequency energy is tolerable. Preferably the filler medium has a power dissipation characteristic less than that of the surrounding earth formations.