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Line 20: − + − [[file:determination-of-water-resistivity_fig1.png|left|thumb|{{figure number|1}}Example of a normal SP deflection. Copyright: Schlumberger Educational Services, 1987.]]+ − + + − − [[file:determination-of-water-resistivity_fig2.png|thumb|{{figure number|2}}Example of a reverse SP deflection.<ref name=pt04r3>Dewan, J. T., 1983, Essentials of modern open-hole log interpretation: Tulsa, OK, Penn Well Books.</ref>]]
Water resistivity determination (view source)
Revision as of 21:46, 21 May 2014
, 21:46, 21 May 2014→SP method
==SP method==
==SP method==
<gallery mode=packed heights=300px widths=300px>
file:determination-of-water-resistivity_fig1.png|{{figure number|1}}Example of a normal SP deflection. Copyright: Schlumberger Educational Services, 1987.
file:determination-of-water-resistivity_fig2.png|{{figure number|2}}Example of a reverse SP deflection.<ref name=pt04r3>Dewan, J. T., 1983, Essentials of modern open-hole log interpretation: Tulsa, OK, Penn Well Books.</ref>
</gallery>
===Principle===
===Principle===
The first step in the interpretation of the [[Basic open hole tools#Spontaneous potential|SP log]] is the establishment of “sand” and “shale” lines, as shown in [[:file:determination-of-water-resistivity_fig1.png|Figure 1]]. These are arbitrary limits, with the sand lines normally representing the maximum deflection to the left and shale lines representing the maximum deflection to the right (in shales). Deflections to the left of the shale line are regarded as normal or negative, and correspond to porous and permeable zones containing a more saline interstitial water than the drilling mud (''R''<sub>w</sub> R<sub>mf</sub>).
The first step in the interpretation of the [[Basic open hole tools#Spontaneous potential|SP log]] is the establishment of “sand” and “shale” lines, as shown in [[:file:determination-of-water-resistivity_fig1.png|Figure 1]]. These are arbitrary limits, with the sand lines normally representing the maximum deflection to the left and shale lines representing the maximum deflection to the right (in shales). Deflections to the left of the shale line are regarded as normal or negative, and correspond to porous and permeable zones containing a more saline interstitial water than the drilling mud (''R''<sub>w</sub> R<sub>mf</sub>).