CORROSION INHIBITION APPARATUS FOR DOWNHOLE ELECTRICAL HEATING

摘要

Corrosion inhibition apparatus in an electromagnetic heating system for in situ downhole heating in an oil well or other mineral fluid well that includes an A.C. power source for a high amperage, low frequency heating current (e.g. over 50 amperes at 0.01 to 35 Hz) and a D.C. bias source for generating a low amplitude (e.g., less than one ampere) current for corrosion inhibition, both sources connected to a downhole electrode. The bias source includes at least one semiconductor device, connected in the main A.C. heating circuit, in a bias circuit that develops a net D.C. voltage differential of the polarity required for corrosion inhibition in response to the A.C. heating current.