Fracture aperture estimation using electrical image logs (FMI)and Acoustic (SS)

Abstract

Summary The fracture characterization-based borehole image provides information about the fracture morphology (Open, cemented, induced, …) and in case of water-based mud, fracture aperture can be estimated using electrical image (FMI*). Fracture apertures processing based on the measured excess current as the tool crossed the fracture. The aperture calculation follows an equation published by Luthi and Souhaite, 1990. The Acoustic measurement (Sonic Scanner) determine anisotropy which can be classified as stress induced fractures, intrinsic anisotropy (Natural open Fracture, Layers) using dispersion plots. The ability of Sonic Scanner to distinguish between open and close fractures, refine the fracture identification from borehole image and provides accurate open fracture sets that can be used for fracture aperture estimation. This approach was applied in Algeria (for Tight gas sandstones reservoirs and the highest dry gas potential in the Sahara region) having as objective to provide client estimated value of fracture aperture to update their DFN model.