Hey guys,
I am trying to find values for the resistivity or resistance for the seeberger sandstone (any other sandstone will do as an approximation). Is there literature available on the mater?
Thank you in advance and until then let's keep making the world a happier place!
We used in our EM modeling:
brine flushed sandstone 0.6 Ohm m
and for reduced (+-70%) oil saturated 16 Ohm m
So you see that it can range a lot depending on porosity and saturation. 300 Ohm m is certainly not the minimum.
Hello,
thank you for the insightful answers. I have three 90% tap-water saturated seeberger sandstone samples (dimensions 100x100x11 mm). They were shocked by a high voltage artificial current (e.g. 400 kA, 12 kV). At the moment, I am trying to estimate the heating power of such a current on the sandstone. From my current knowledge, this is done using the action integral (Integral of I^2(t) * R). The unit should be A^2.s (equivalent to kJ/ohm).
I understand and I agree with all what you mentioned. However, how can I tackle this problem? Is it even possible to solve this? Do I have perhaps to make an assumption that R=1? Using the resistivity, I will have a unit problem as you can see (that is why I asked the dumb question about the resistance). I hope you can assist me further.
Thank you in advance and until then let's keep making the world a happier place
P.S: I already calculated the active average power
Thank you Thomas, that is what I was looking for. Which rho value should I use however for the 90% tap-water saturated seeberger sandstone. Here are the parameters that might be useful:
Density: 2.25 +- 0.04
Unsaturated pore space 2.3 +- 0.1 %
90% tap-water saturated (tap water from Germany)
Between 12 and 23 vol% porosity
97% SiO2 and 3 wt% accessory minerals.
Oxides wt% is as follows:
SiO2 94.77 ± 0.9
Al2O3 3.11 ± 0.1
Fe2O3 0.45 ± 0.09
MnO Trace
MgO 0.12 ± 0.02
CaO 0.05 ± 0.01
Na2O 0.15 ± 0.05
K2O 0.23 ± 0.01
TiO2 0.31 ± 0.04
P2O5 0.02 ± 0.01
Ni [ppm] 3.33 ± 0.41
Co [ppm] 0.96 ± 0.41
Cr [ppm] 63.33 ± 21.21
Huge thanks for taking the time to help me out!
Hi Houssam,
absolute values is impossible to define. As you know apparent resistivity depends on many geological and geophysical factors. E.g mineralogical composition of sandstones - sometimes is dominant quarz component, sometimes carbonatic one, or mice. Chemical composition of underground water is often a decisive factor equally as porosity and hydrulic transmissivity. If you add to this tectonic faulting, stratification ( sometimes metamorphose) that may by in several asimutes you have to consider an anisotropy which can contributes into various levels of the resisitivity field . There are many others parameters influencing this field (thickness and character of cover, etc...). Therefore you may characterize this type of sandstone within frame of some concrete boundered locality which exhibits almost the same geological features, where are sandstones located in the same geological environment. Every other adding localities causes spreading of resistivity interval what determines ambiguosity in interpretation. I know, my explanation is a bit complicated, but believe me my more than 40 years experience taught me to be modest and lowly in interpretive conclusions. I wish you good luck and persistency in revealing geophysical secretes.
Regards
Ludo
Thank you all for the very informative answers. I really appreciate your help.
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