oa Effect of Heterogeneity of Hydraulic Conductivity on Streaming Potential

Self-potential (SP) is electrical potential mainly generated by thermoelectric, chemical and streaming potentials in the subsurface. The flow of groundwater is often recognized as a bigger source of SP. Using this feature, there are many attempts to localize and quantify flows of liquid in the soil, including groundwater. In case that underground structure is homogeneous, electrical current density according to ground-water flow becomes uniform. Therefore SP on the surface increases monotonically from upstream to downstream of groundwater flow. As a basic interpretation of SP, the direction of increase in SP corresponds with the direction of groundwater flow. However, the anomalous fluctuations of SP start to appear for subsurface inhomogeneous groundwater flow due to the non-uniform conveyance of changes. Extra charge occurs on the boundary of these parameters. As a result, local minimum or maximum in the profile of SP generate just above the boundaries. Our simulation shows that the anomalies of permeability and coupling-coefficient in the subsurface are predominant parameters to effectively estimate the distribution of surface SP in the existence of inhomogeneous underground flow. The effect of coupling coefficient on the SP is often simulated on the underground flow scale. Some anomalies of SP are explained by the inhomogeneous of coupling coefficient. Simple model simulation, for example the well-pump model shows the effect of hydraulic conductivity on the SP. However, SP anomalies that are generated by inhomogeneity of hydraulic conductivity are not simulated on the underground flow scale. We compare the difference of these anomalies and study the different feature of SP anomaly that is generated by hydraulic conductivity from it by coupling coefficient.