Fracture Connectivity of Fractal Fracture Networks Estimated using Electrical Resistivity

Abstract

This paper discusses a method for characterizing fractures in geothermal reservoirs using conductive fluid injection and electrical resistivity measurements. Discrete fractal fracture networks were modeled and GPRS flow simulator was first used to simulate the flow of a conductive tracer through the reservoir, and then applied to solve the electric fields at each time step by utilizing the analogy between Ohm’s law and Darcy’s law. The time history of the electric potential difference between the injector and the producer gives information about the fracture network because the potential difference drops as conductive fluid fills up the fracture paths. Therefore, the fracture connectivity of a fractal fracture network could be estimated with inverse modeling using the time history of the electric potential and the tracer history at the producers.