کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4741020 1358627 2006 21 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Pore geometry of sandstone derived from pulsed field gradient NMR
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فیزیک زمین (ژئو فیزیک)
پیش نمایش صفحه اول مقاله
Pore geometry of sandstone derived from pulsed field gradient NMR
چکیده انگلیسی

Several parameters of pore geometry are needed for estimating permeability which is a key parameter for the characterization of reservoir sandstones. Powerful techniques for probing the pore space are the self-diffusion and the relaxation time NMR methods. However, the quality of results depends on the petrophysical model which underlies the interpretation of measurements. We applied the pulsed field gradient nuclear magnetic resonance (PFG-NMR) technique and measured time-dependent self-diffusion coefficients, D(Δ), of water in anhydrite cemented sandstones with low porosity and high tortuosity. The conventional method of fitting data with a function (Padé approximation) of the surface-to-volume ratio and the tortuosity yielded uncertain results. As part of a novel approach, we developed a numerical simulation code based on physical principles and a fractal pore space model. We compared our method with the Padé approximation and tested with data from the literature. For porous media with low tortuosity values and simple geometry such as randomly packed glass beads, both methods are in good agreement and give similar results. In sedimentary rocks, however, the new method of calculation is able to determine more accurate details of the pore geometry. However, its main advantage occurs in porous media with fractal geometry or with constricted pores, where the D(Δ)/D0 curves deviate from the characteristic shape that is found for randomly packed glass beads.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Applied Geophysics - Volume 58, Issue 3, March 2006, Pages 232–252
نویسندگان
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