The internal magnetic field distribution, and single exponential magnetic resonance free induction decay, in rocks
The internal magnetic field distribution, and single exponential magnetic resonance free induction decay, in rocks
复制标题
DOI：
10.1016/j.jmr.2005.05.001
复制
发表时间：
2005-08-01
影响因子：
2.2
通讯作者：
Balcom, BJ
中科院分区：
文献类型：
--
作者：
Chen, Q;Marble, AE;Balcom, BJ
当流体饱和的多孔介质经受施加的均匀磁场时，由于孔隙填充流体和固体基质之间的磁化率差异，在孔隙空间内感应出内部磁场。基于沉积岩薄片孔隙结构，模拟了沉积岩内部磁场的微观分布及其梯度。仿真结果得到了实验验证。我们表明，“衰减由于在内场扩散”磁共振技术可以应用于测量部分饱和多孔介质中的孔径分布。我们首次观察到多孔岩石中的内部磁场及其梯度具有洛伦兹分布，平均梯度值为零。内部磁场的洛伦兹分布源于这些多孔介质中大的磁化率对比度和固有的无序孔隙结构。我们证实，在流体饱和多孔介质中常见的单指数磁共振自由感应衰减源于洛伦兹内部场分布。通过模拟和实验，观察到的磁共振线宽之间的线性关系，并在多孔介质中的磁化率差和所施加的磁场的产品，通过。(c)2005年爱思唯尔公司All rights reserved.
When fluid saturated porous media are subjected to an applied uniform magnetic field, an internal magnetic field, inside the pore space, is induced due to magnetic susceptibility differences between the pore-filling fluid and the solid matrix. The microscopic distribution of the internal magnetic field, and its gradients, was simulated based on the thin-section pore structure of a sedimentary rock. The simulation results were verified experimentally. We show that the 'decay due to diffusion in internal field' magnetic resonance technique may be applied to measure the pore size distribution in partially saturated porous media. For the first time, we have observed that the internal magnetic field and its gradients in porous rocks have a Lorentzian distribution, with an average gradient value of zero. The Lorentzian distribution of internal magnetic field arises from the large susceptibility contrast and an intrinsic disordered pore structure in these porous media. We confirm that the single exponential magnetic resonance free induction decay commonly observed in fluid saturated porous media arises from a Lorentzian internal field distribution. A linear relationship between the magnetic resonance linewidth, and the product of the susceptibility difference in the porous media and the applied magnetic field, is observed through simulation and experiment. (c) 2005 Elsevier Inc. All rights reserved.