T. Eltsov, T.W. Patzek
Society of Exploration Geophysicists Annual Meeting Technical Program, (2018)
We present a technique for the detection of integrity of the magnetic cement behind resistive fiberglass casing. Numerical simulations show that an optimized induction logging tool allows one to detect small changes in the magnetic permeability of cement through a non-conductive casing in a vertical (or horizontal) well. Changes in magnetic permeability influence mostly the real part of the vertical component of magnetic field. The signal attenuation is sensitive to a change of magnetic properties of the cement. Our simulations show that optimum separation between the transmitter and receiver coils ranges from 0.25 to 0.6 meters, and the most suitable magnetic field frequencies vary from 0.1 to 10 kHz. Our goal is to build cheap, long-lasting, low-temperature (<150°C) geothermal wells with water recirculation.