GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.3 ______ ___ GNGTS 2023 Equation 2 represents an average conductance multiplied by a transverse resistivity which is constant along depth. Using the previous relationships an electrical model can be obtained from the apparent measurements from the MT survey (Gómez-Treviño 1996). However, the electrical model derived from the apparent measurements is different from the model obtained by the exploratory wells, the location in depth for a given resistivity value varies for different models. Based on the previous statement, in this work it is proposed to model the ∆ difference between models using different regression techniques. To obtain the differences between models and to properly approximate those differences by means of a polynomial function, it is proposed to use the cumulative resistivity. The cumulative resistivity can be defined as the integrated total resistivity from the surface up to a certain point in depth and was defined by (Price 1949) as ρ ( ) = 0 ∫ ρ( ) (4) The difference between models were obtained by means of When Δ = − ρ ≈ ρ ( ) (5) The difference then is modeled by means of a polynomial regression considering that a defined ∆ relationship between an independent variable and a dependent variable is established. And once the polynomial expression is obtained it can be used to correct the misfit between the model obtained from the apparent data and the true model. However, the correction was obtained for the cumulative resistivity values, so to retrieve a non-cumulative model, a numerical derivative must be applied by means of ρ( ) = ρ +1 ( )− ρ ( ) +1 ( )− ( ) (6)