Do anyone have standard resistivity table that contain differences between unsaturated rocks and saturated rocks ? example dry sandstone and saturated sandstone, dry tuff and saturated tuff, etc. THANKS A LOT ! :)
Values of electrical resistivity in rocks change by a wide range due to the resistivity of the pore fluid, porosity, degree of saturation, mineral composition and tortuosity. For that reason "standard values" are not available. You may refer to a number of geophysics books (e.g., Telford et al.; Reynolds, etc.) that would tabulate ranges for differetn materials. For your consideration, I am attaching a paper we published with electrical resistivity values for sandstone.
Good luck!
Dante
Article Irreducible Water Saturation from Capillary Pressure and Ele...
The resistivity values of the rock formations depends on their porosity, permeability, fractures, fissures, grain size. Different rocks shows different relativities. For example dry unconsolidated materials shows high resistivity whereas saturated unconsolidated material shows low resistivity values. Hence standard values are not possible because of diverse geological conditions. Refer any Hydrogeology books such as DK Todd, HM Raghunath etc.
Hermawan, electrical conductivity or resistivity of a porous rock media is controlled by a number of factors, which include but may not be limited to the following: porosity(permebility), presence of pore water in the poor spaces and ofcourse salinity which is a function of dissolved minerals present in the pore spaces. In adition to all these factors, some other factors like temperature and other environmental conditions may also affect the resistivity of rocks. Thus, even if a rock of the same minerological composition is found in the polar region and at the equator, there will be variations in their resistivity values. Therefore, several of the standard tables in Telford et al.,1976; Dobrin et al .,1976,etc are to a first approximation a guide as they may not be in agreement with the resistivity of similar rocks measured else where. Therefore, I humbly advice that whatever standard table you are looking at , take into consideration the temperature/ climatic conditions and ofcourse the local geology of the place where the data is been measured.
Dear all,
I'm searching something like this, this one i got from Loke, 2000. But, the table does not provides the resistivity of materials in dry and saturated condition. Anyway thanks for your help Mr. @Dante Fratta, Mr. @Alex Opara and Mr. @Raju.
Pandurang Pisal, what is the source of the attachment you shared? It looks like a modified version of the Palacky (1988) figure.
In my opinion; yes, we have many factors that control the resistivity values. But maybe researchers can try to reduce the factor with several efforts.
- try to consider tropical countries vs 4 seasons countries
- compilation of rock samples from drilling activities also maybe can give better ranges of the resistivity value.
-correlate it value with other geophysical method like IP.
Do not depend on Resistivity tables. There are numerous factors affecting resisitivity as porosity, permeability, size of grains, fabric, packing, sorting, depth, diagenesis......etc. Each area has its specific resistivity.
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