Hürlimann M D, Latour L L, Sotak C H
Schlumberger-Doll Research, Ridgefield, CT 06877.
Magn Reson Imaging. 1994;12(2):325-7. doi: 10.1016/0730-725x(94)91548-2.
Recent theoretical work has shown that the time dependence of the effective diffusion constant in porous media contains information about the surface to pore volume ratio, the tortuosity and other petrophysical information. We have measured the effective diffusion constant in a water saturated core of Fontainebleau sandstone as a function of diffusion time. From the short time behavior, we are able to extract the surface to pore volume ratio. This value can be combined with the spin-lattice relaxation rate measured on the same core under identical conditions to yield the surface relaxivity rho = 1.6 x 10(-5)m/s. Measurements at 25.0 degrees C and 40.0 degrees C demonstrate that the effect of surface relaxation on the measured diffusion coefficient is small, as predicted by theory.
最近的理论研究表明，多孔介质中有效扩散常数的时间依赖性包含了有关比表面积、曲折度和其他岩石物理信息。我们测量了饱和水的枫丹白露砂岩岩芯中的有效扩散常数随扩散时间的变化。从短时间行为中，我们能够提取比表面积。该值可以与在相同条件下在同一岩芯上测得的自旋-晶格弛豫率相结合，得出表面弛豫率ρ = 1.6×10⁻⁵m/s。在25.0℃和40.0℃下的测量表明，如理论所预测的，表面弛豫对测量扩散系数的影响很小。
