I have 1-D subsurface resistivity measurements ( using Schlumberger electrode array) as well as borehole data up to the depth of 30 m. Is it compulsory to perform curve fitting using the master curves ? Can i directly use the apparent resistivity vs depth plot to match it with the borehole data.
Dear Navneet,
You should do the following :
1- Obtain the 1D resistivity model from your VES data using a curve fitting technique.
2- Compare your 1D resistivity model with borehole data.
Note: Master curve is a very old technique and not reliable. Also,
use of the apparent resistivity vs depth plot is not a good idea.
you can derive PDM using PSO variants and other GOMs through inversion process with a threshold of objective function (see Fernandez Martinez and their colleges paper's, Sungkono and Warnana paper's)
Dear Navneet, depending on the kind of borehole profile you have you shall take different procedures. Remember that the model obtained from the inversion of the Schlumberger sounding is an inferred model, which may be affected by static-shifts; and the induction profile is a direct measurement of the resistivity of the borehole wall.
If you have the induction profile of the borehole you cannot compare it with the Schlumberger apparent resistivity curve. You should perform the inversion of the latter under the constraint of the borehole profile.
However, if you have an electrical profile of the borehole, depending on the arrangement of the electrodes, you may need to perform the inversion of both apparent resistivity curves before any comparison.
Dear Navneet Kaur ,
Try to use the advanced software with focusing on the forward and inverse model in your interpretation.
regards
Dear Navneet Kaur,
1. If data acquired is in plain area (less topographic variations) then curve matching will yield more frutifull results, if topographically vairated area then you have to closely monitor the surfacial changes otherwise curve matching may yield abnormal results
2. Resisitivty is an indirect method so your resisitivty section may not match with bore data as bore gives detail even of small beds which are not detected by resisitivty measurements
3. One thing you can do carry out curve matching and then adjust your curve according to borehole but for that you will be needing more then one point and bore as well, also the subsurface geological strata must be kept in mind
4. Apparent resistivity depth section is not a good idea because of surface spacing adjustments, also bed thicknesses will not be known, so it is not recommended
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