From Conceptual Models to Apparent Models with the Geophysical Measurements

As the advance of various non-destructive geophysical exploration technologies, one would be able to establish the apparent model that can further show the features of the geological/hydrogeological models, instead of the conceptual model pictured from professional concept. We used the vast surface resistivity measurements collected in the past 40 years, as well as the limited borehole records to illustrate how to establish a three-dimensional (3D) hydrogeological apparent model. Core records from monitoring wells in the area were used for the training data to help determining the resistivity ranges of the gavel, sand, and muddy sediments in the coastal plain. These resistivity measurements were inverted and interpolated for rendering a three dimensional resistivity volume that represents the general resistivity distribution in the coastal-plain systems. The resistivity model was transferred into the formation factors (FI) model in order to take the groundwater conductivity into account. Lastly we transfer the FI model into the gravel-sand-clay apparent model with the classification criteria from previous petrophysical analysis. Because there are more resistivity measurements than the limited geological boreholes, the apparent model is better to represent the detailed sedimentary structures than the traditional over-simplified conceptual models.