Patent ID: 7109457

Claim:
A method for heating a hydrocarbon-bearing formation, comprising: (a) subjecting said hydrocarbon-bearing formation to an alternating current field produced by applying a radio frequency waveform at a predetermined variable frequency with a signal generating unit, said signal generating unit having a generally constant output impedance; (b) measuring an actual impedance of said hydrocarbon-bearing formation; (c) determining an effective load impedance, said effective load impedance initially dependent upon said actual impedance of said hydrocarbon-bearing formation, said effective load impedance being determined by at least one of measuring a voltage and current of an applied radio frequency waveform and computing a phase angle difference, and measuring a forward power level of said radio frequency waveform applied to said hydrocarbonaceous matter and a reverse power level of said radio frequency waveform reflected from said hydrocarbon-bearing formation with circuitry of said signal generating unit; (d) comparing said effective load impedance with said output impedance of said signal generating unit; and (e) automatically matching said effective load impedance to said output impedance of said signal generating unit by at least one of adjusting the frequency at which said radio frequency waveform is applied and tuning a tunable impedance matching network such that said effective adjusted load impedance is approximately equal to said output impedance of signal generating unit.