Analysis of Electromagnetic Induction for Hydraulic Fracture Diagnostics in Open and Cased Boreholes

In this paper, the sensitivity and detectability of an electromagnetic induction tool for hydraulic fracture detection are analyzed by calculating the electromagnetic response from an orthogonal transverse fracture (OTF) in an open or cased borehole using the improved numerical mode matching method. The OTF is modeled as a slim circular disk, which is axially symmetric with respect to the borehole axis and filled with a conductive or magnetic proppant. The feasibility of the induction tool for fracture diagnostics was validated via scaled-down experimental measurements. We then quantitatively analyze the induction response sensitivity to different proppant parameters, such as conductivity and permeability, to evaluate the effectiveness of the induction logging tool for fracture detection. The analysis reveals that the short-spaced receiver can accurately locate the fracture position and distinguish small-sized fractures, while the long-spaced receiver can differentiate fractures with large dimension. Casings with different thicknesses, conductivities, and permeabilities are modeled together with the fracture to investigate their effects in fracture detection. Finally, the application of the induction tool to a fracture network is evaluated.