Fracture diagnostics using a low-frequency electromagnetic induction method

The implementation of a low-frequency electromagnetic induction tool for propped-fracture detection and diagnostics requires in-depth examination of the reliability and accuracy of the method across fractures with realistic geomechanical features. Likewise, the method relies on the effective placement of electrically conductive proppant within the generated fractures for measurable sensitivity. We invoke a fast Fourier-transform-based volume integral equation simulation method for forward modeling to simulate the electromagnetic response of realistic fracture geometries generated in hydro-fracturing operations and under practical rock conditions. Improved performance is achieved by removing model features which are of little significance to the results and yet cause a significant computational overhead. To properly account for the effective proppant conductivity, we introduce a new technique for the measurement of proppant conductivity using a resistivity core holder. The conductivity of petroleum coke - a potential candidate to be used in the field - is tested in the laboratory. Resulting measurements are used to forward simulate the tool's response to multiple fracture geometries and sizes. Distinct results are obtained for fractures with different spatial distributions of proppant, indicating the possibility of distinguishing between them using a future inverse solver.