Note that an equivalent “quick look” solution can be obtained by an overlay technique using logarithmically scaled ''R''<sub>t</sub> and ''R''<sub>xo</sub> logs. If one log is placed over the other and shifted so that the two curves coincide in clean, water-bearing zones, the 1 ohm-m line on the ''R''<sub>xo</sub> log grid will lie on the ''R''<sub>t</sub> grid at a value equal to ''R''<sub>w</sub>/''R''<sub>mf</sub>. Since ''R''<sub>mf</sub> is known, ''R''<sub>w</sub> can then be easily calculated. [[:file:determination-of-water-resistivity_fig4.png|Figure 4]] shows an example of original and shifted logs indicating a ''R''<sub>t</sub>/''R''<sub>mf</sub> ratio of 0.45. | Note that an equivalent “quick look” solution can be obtained by an overlay technique using logarithmically scaled ''R''<sub>t</sub> and ''R''<sub>xo</sub> logs. If one log is placed over the other and shifted so that the two curves coincide in clean, water-bearing zones, the 1 ohm-m line on the ''R''<sub>xo</sub> log grid will lie on the ''R''<sub>t</sub> grid at a value equal to ''R''<sub>w</sub>/''R''<sub>mf</sub>. Since ''R''<sub>mf</sub> is known, ''R''<sub>w</sub> can then be easily calculated. [[:file:determination-of-water-resistivity_fig4.png|Figure 4]] shows an example of original and shifted logs indicating a ''R''<sub>t</sub>/''R''<sub>mf</sub> ratio of 0.45. |