Time-lapse imaging of particle invasion and deposition in porous media using in situ X-ray radiography

Abstract

This paper introduces time-lapse radiography as an in situ technique to image and quantify changes in the internal structure of a porous medium with sub-second temporal resolution. To demonstrate the technique's potential, an experiment was performed using a model system involving flow of a suspension containing ground marble particles through a porous bed of compacted glass beads housed within a pressurized flow rig. During the experiment, particle deposition occurred both within the internal porous structure and on its surface (forming a filter cake). The volume of particles deposited was derived from changes in the grey scale of the radiographs. At the initial stages of the experiment, the volume of particles deposited internally was seen to increase linearly with time. The subsequent growth and compaction of an external filter cake decreased the rate of internal particle deposition. The filter cake's structure was observed to fail owing to increasing stress at higher pressures. The demonstrative experiment illustrates the potential of time-lapse radiography as a new tool to elucidate mechanisms underpinning formation damage, and to optimise drilling fluids and enhanced oil recovery (EOR). A critical assessment of the technique's advantages and limitations to characterise particulate behaviour within porous media is included.