  Self-potential signals can be generated by different sources and can be
decomposed in various contributions. Streming potential is the contribution due
to the water flux in the subsurface and is of particular interest in
hydrogeophysics and reservoir characterization. Being able to estimate water
fluxes in porous and fractured media using streaming potential data relies on
our understanding of the electrokinetic coupling at the mineral-solution
interface and our capacity to understand, model, and upscale this phenomenon.
Two main approaches have been proposed to predict streaming potential
generation in geological media. One of these approaches is based on determining
the excess charge which is effectively dragged in the medium by water flow. In
this chapter, we describe how to model the streaming potential by considering
this effective excess charge density, how it can be defined, calculated and
upscaled. We provide a short overview of the theoretical basis of this approach
and we describe different applications to both water saturated and partially
saturated soils and fractured media.
