Selective excitation of heating electrodes for oil wells

An electrical control for an iterated heating electrode array for an oil well, the oil well comprising an initial well bore extending downwardly from the surface of the earth through overburden formations and a producing well bore in communication with and extending from the initial well bore into an oil producing formation, the electrode array including a plurality of electrically isolated conductive heating electrodes spaced longitudinally through the producing well bore, and a plural-conductor energizing cable for electrically energizing the heating electrodes in each set of electrodes with A.C. power at a phase displacement of at least 90.degree., the electrical control comprising:

• a plurality of telemeter sensors, one for each controllable heating electrode and all coupled to a telemetry communication pathway, for generating telemeter data signals indicative of a parameter representative of the operating condition of a controllable heating electrode, which telemeter data signals are transmitted to the surface via the telemetry communication pathway;
• a surface telemeter apparatus, coupled to the telemetry communication pathway, for receiving the telemeter data signals and for generating telemeter actuation signals based on the telemeter data signals, which telemeter actuation signals are transmitted down hole via the telemetry communication pathway;
• a plurality of signal-actuated power switches, each connecting one controllable heating electrode to a conductor of the energizing cable to electrically energize the heating electrode;
• and
• a plurality of telemeter channels, one for each controllable heating electrode;
• all heating electrodes being coupled to the energizing cable, each connected to one power switch to apply actuation signals to the associated power switch, the actuation signal being representative of the telemeter actuation signals.

An electrical control for an iterated heating electrode array for an oil well, the oil well comprising an initial well bore extending downwardly from the surface of the earth through overburden formations and a producing well bore in communication with and extending from the initial well bore into an oil producing formation, the electrode array including a plurality of electrically isolated conductive heating electrodes spaced longitudinally through the producing well bore, and a plural-conductor energizing cable for electrically energizing the heating electrodes in each set of electrodes with A.C. power at a phase displacement of at least 90.degree., the electrical control comprising:

• a plurality of telemeter sensors, one for each controllable heating electrode and all coupled to a telemetry communication pathway, for generating telemeter data signals indicative of a parameter representative of the operating condition of a controllable heating electrode, which telemeter data signals are transmitted to the surface via the telemetry communication pathway;
• a surface telemeter apparatus, coupled to the telemetry communication pathway, for receiving the telemeter data signals and for generating telemeter actuation signals based on the telemeter data signals, which telemeter actuation signals are transmitted down hole via the telemetry communication pathway;
• a plurality of signal-actuated power switches, each connecting one controllable heating electrode to a conductor of the energizing cable to electrically energize the heating electrode;
• and
• a plurality of telemeter channels, one for each controllable heating electrode;
• all heating electrodes being coupled to the energizing cable, each connected to one power switch to apply actuation signals to the associated power switch, the actuation signal being representative of the telemeter actuation signals;
• power for the downhole telemetry receivers and transmitters being supplied from the energizing cable.

An electrical control for an iterated heating electrode array for an oil well, the oil well comprising an initial well bore extending downwardly from the surface of the earth through overburden formations and a producing well bore in communication with and extending from the initial well bore into an oil producing formation, the electrode array including a plurality of electrically isolated conductive heating electrodes spaced longitudinally through the producing well bore, and a plural-conductor energizing cable for electrically energizing the heating electrodes in each set of electrodes with A.C. power at a phase displacement of at least 90.degree., the electrical control comprising:

• a plurality of telemeter sensors, one for each heating electrode and all coupled to the energizing cable, for generating telemeter data signals indicative of a parameter representative of the operating condition of one heating electrode, which telemeter data signals are transmitted to the surface via the energizing cable;
• a surface telemeter apparatus, coupled to the energizing cable, for receiving the telemeter data signals and for generating telemeter actuation signals based on the telemeter data signals, which telemeter actuation signals are transmitted down hole via the energizing cable;
• a plurality of signal-actuated power switches, each connecting one heating electrode to a conductor of the energizing cable to electrically energize the heating electrode;
• and
• a plurality of telemeter channels, one for each heating electrode and all coupled to the energizing cable, each connected to one power switch to apply actuation signals to the associated power switch, the actuation signal being representative of the telemeter actuation signals.