Specifying of aquifer characteristics using forward and inverse modeling of DC-resistivity and TEM methods.

Exploration and determination of the hydro-geo-electrical characteristics of an aquifer can be done by applying the forward (initial multi-layers), and the inverse (final layered) models for interpreting the DC-resistivity (VES) and TEM data. So, 22 VES using Schlumberger configuration (AB/2 = 500-700m) and 12 TEMS using in-loop configuration (square, ℓ = 200m) were carried out at the West El-Minia selected area for studying the Oligocene Clastic and Carbonate aquifers. VESs were interpreted for studying the shallow resistive and conductive layers, as well as faults delineation. TEMs were interpreted for shallow and deep conductive layers discrimination. The VES and TEM inverse models were examined with the drilling data and construed the subsurface into four units; dry Oligocene Clastics (173-467 Ω.m), dry limestone (273-374 Ω.m), saturated Oligocene Clastics (Oligocene aquifer) (2-107 Ω.m), then saturated fractured Eocene limestone to shaly limestone (5-188 Ω.m). Groundwater depths (62-131m) and thicknesses variation were estimated, as well as the faults location. Two hydro-geo-electrical sections were built for simulating the resistivity values and their connotations, and managing in choosing the promised locations for drilling wells. The ramp-off time effect was studied and found that ∼50-∼100m shallow high resistive thickness didn't defined from the TEM data in which the max penetration depth was 672m. The available well logging data were analysed to reveal the pure saturated zones, the volume of shale of 0%-100% and the porosity values of ∼9%-∼35% in the Oligocene aquifer and of ∼4%-∼15.5% in the carbonate aquifer. So, the forward and inverse models application and soundings integration are considered robust tools for estimating and simulating the aquifer characteristics.