Forward modeling using finite difference method for fractured hard rocks tracing via three-electrode array
© Reza Ghanati, Babak Aranifar, Mohammad Kazem Hafizi
Ever-increasing population of the world and decrease of the rain average in the recent years has led to the significance of
the groundwater exploration. Among the various applicable techniques of the groundwater exploration, electrical methods play an
important role. The forward modeling is one of the sensitive techniques, which has been extensively used in all branches of geophysics.
This technique refers to a mathematical process of computing theoretical response of a given geophysical method applied to structures
with known size, shape and position. In this paper, we provided a new geoelectric forward modeling software. For testing the software,
it must be compared with the systems which theoretically have analytical responses. Hence, we made a synthetic model and some
measurements were conducted over the model using pole-pole array. The results obtained from the software, exact solution and
Res2DMod software to the synthetic model showed that the responses of the Res2DMod represent higher deviation in comparison
with the provided software responses. Moreover, to investigate the proficiency of the software, a fracture zone saturated with water
which has lower resistivity to its surroundings, analogous to the study area, using the provided software was modeled and the
responses of the model to three-electrode array were calculated. The pseudosection from the three-electrode array measurements
on the synthetic model revealed the vertical fracture zone. We also carried out a field survey by means of the three-electrode array in a
hard rock terrain in Pakdeh, North of Iran. The two-dimensional (2D) inversion of the three-electrode apparent resistivity data led to
locate a low-resistivity area implicating the presence of fracture zone in the study area. We validated geophysical data by using
stratigraphy of a borehole drilled nearby.
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