Mapping three-dimensional oil distribution with pi-EPI MRI measurements at low magnetic field

作者：Li Ming; Xiao Dan; Romero Zeron Laura; Marica Florea; MacMillan Bryce; Balcom Bruce J^*

来源：Journal of Magnetic Resonance, 2016, 269: 13-23.

DOI：10.1016/j.jmr.2016.05.008

• 3D oil distribution
• pi Echo Planar Imaging
• Fast Spin Echo
• SPRITE
• MRI

Magnetic resonance imaging (MRI) is a robust tool to image oil saturation distribution in rock cores during oil displacement processes. However, a lengthy measurement time for 3D measurements at low magnetic field can hinder monitoring the displacement. 1D and 2D MRI measurements are instead often undertaken to monitor the oil displacement since they are faster. However, 1D and 2D images may not completely reflect the oil distribution in heterogeneous rock cores.
In this work, a high-speed 3D MRI technique, pi Echo Planar Imaging (pi-EPI), was employed at 0.2 T to monitor oil displacement. Centric scan interleaved sampling with view sharing in k-t space was employed to improve the temporal resolution of the pi-EPI measurements. A D2O brine was employed to distinguish the hydrocarbon and water phases. A relatively homogenous glass bead pack and a heterogeneous Spynie core plug were employed to show different oil displacement behaviors. High quality 3D images were acquired with pi-EPI MRI measurements.
Fluid quantification with pi-EPI compared favorably with FID, CPMG, 1D-DHK-SPRITE, 3D Fast Spin Echo (FSE) and 3D Conical SPRITE measurements. pi-EPI greatly reduced the gradient duty cycle and improved sensitivity, compared to FSE and Conical SPRITE measurements, enabling dynamic monitoring of oil displacement processes. For core plug samples with sufficiently long lived T-2, T-2*, pi-EPI is an ideal method for rapid 3D saturation imaging.

• 出版日期2016-8