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|Title:||ESTIMATION OF PERMEABILITY OF SHALY SAND FROM INDUCED POLARIZATION RELAXATION TIME SPECTRA AND COMPARE IT WITH NMR DATA|
EARTH SCIENCE ENGINEERING
|Abstract:||The induced polarization (IP) decay curve can be inverted in order to get the 1P relaxation time spectrum. Singular value Decomposition is used as the inversion algorithm along with nonnegative restriction as it is possible that there are minus terms in the solution of the amplitude of the relaxation spectrum and this is incredible in physical meaning. The complete analysis of the problem infer that the appropriate number of relaxation arrangement points in relaxation data inversion lies in the range of 32 to 64. In this range the attenuation of noise is better and resolution is good. The IP relaxation spectrum indicates the pore size distribution and thus permeability of the shaly sand as the IP response is measured only along conducting pathways through the formation; therefore, disconnected and dead-end pores, which do not contribute to permeability, are not measured. Combining the average relaxation time (geometric average time) with the porosity can improve the accuracy of estimation of the permeability in comparison to that obtained using total porosity from core measurements. For nuclear magnetic resonance (NMR), a correlation between mean relaxation time and permeability is widely applied. The nuclear magnetic relaxation of hydrogen in a wetting pore fluid of rocks is controlled by slow relaxation in the free pore fluid and fast relaxation in the direct vicinity of the pore surface. Comparison between IP estimated permeability and NMR estimated permeability is done for the same relaxation time and it is justified that IP is more reliable, cost effective and safer method.|
|Appears in Collections:||MASTERS' DISSERTATIONS (Earth Sci.)|
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