MRI Centre, Department of Physics, University of New Brunswick, P.O. Box 4400, 8 Bailey Drive, Fredericton, Canada E3B 5A3.
J Magn Reson. 2012 Oct;223:120-8. doi: 10.1016/j.jmr.2012.08.004. Epub 2012 Aug 14.
A time-efficient MRI method suitable for quantitative mapping of 3-D velocity fields in sedimentary rock cores, and granular samples is discussed. The method combines the 13-interval Alternating-Pulsed-Gradient Stimulated-Echo (APGSTE) scheme and three-dimensional Single Point Ramped Imaging with T(1) Enhancement (SPRITE). Collecting a few samples near the q-space origin and employing restricted k-space sampling dramatically improves the performance of the imaging method. The APGSTE-SPRITE method is illustrated through mapping of 3-D velocity field in a macroscopic bead pack and heterogeneous sandstone and limestone core plugs. The observed flow patterns are consistent with a general trend for permeability to increase with the porosity. Domains of low permeability obstruct the flow within the core volume. Water tends to flow along macroscopic zones of higher porosity and across zones of lower porosity.
讨论了一种适用于沉积岩岩心和颗粒样品中三维速度场定量映射的高效 MRI 方法。该方法结合了 13 间隔交替脉冲梯度激励回波（APGSTE）方案和三维单点 ramped 成像与 T1 增强（SPRITE）。在 q 空间原点附近采集几个样本，并采用受限 k 空间采样，显著提高了成像方法的性能。APGSTE-SPRITE 方法通过对宏观珠包和非均质砂岩和石灰岩岩心塞中的三维速度场进行映射来说明。观察到的流动模式与渗透率随孔隙度增加而增加的一般趋势一致。低渗透率域阻碍了岩心体积内的流动。水倾向于沿宏观高孔隙度带和低孔隙度带流动。
