Elastic waves push organic fluids from reservoir rock

Abstract

Elastic waves have been observed to increase productivity of oil wells, although the reason for the vibratory mobilization of the residual organic fluids has remained unclear. Residual oil is entrapped as ganglia in pore constrictions because of resisting capillary forces. An external pressure gradient exceeding an “unplugging” threshold is needed to carry the ganglia through. The vibrations help overcome this resistance by adding an oscillatory inertial forcing to the external gradient; when the vibratory forcing acts along the gradient and the threshold is exceeded, instant “unplugging” occurs. The mobilization effect is proportional to the amplitude and inversely proportional to the frequency of vibrations. We observe this dependence in a laboratory experiment, in which residual saturation is created in a glass micromodel, and mobilization of the dyed organic ganglia is monitored using digital photography. We also directly demonstrate the release of an entrapped ganglion by vibrations in a computational fluid‐dynamics simulation.

Application of a Novel Ultrasonic Technology to Improve Oil Recovery with an Environmental Viewpoint

“…In another study, Beresnev [26] tried to analyze the mobility of the oil droplets within the porous media-through a capillary-oriented mechanism-afterward the ultrasound waves are radiated. Figure 1 displays a schematic view of the trapped oil.…”

“…In this regard, the systematic review of Beresnev and Johnson [26] collected and analyzed the studies on the methods that took advantage of elastic wave simulation in oil extractionboth ultrasound and seismic waves. This systematic review came to conclusion that both elastic waves and seismic waves are able to increase the rate of permeability as well as production within the porous media.…”

Vibration-induced mobilization of trapped non-aqueous phase liquids in porous media

“…Among them, the simple capillary-physics mechanism presented by Beresnev et al (2005) can explain all experimental observations and is therefore a leading candidate.…”

“…Several mobilization mechanisms, based on the effect of elastic waves to overcome capillary forces by which the dispersed phase was trapped, were proposed by Graham and Higdon (2000), Hilpert et al (2000), Iassonov and Beresnev (2003) and Beresnev et al (2005). However, the capillary-physics mechanism of elastic wave stimulation proposed by Beresnev et al (2005) is one of the most promising explanations for mobilization and flow enhancement of trapped dispersed phase under the implementation of elastic waves, such as vibration.…”

“…Recently Beresnev et al (2005), building on numerical simulations by Graham and Higdon (2000) and Iassonov and Beresnev (2003), have articulated a simple capillaryphysics mechanism to explain ganglia mobilization by low frequency vibrations by considering the behavior of a single non-wetting droplet trapped at the entrance to a constriction in a tubular channel, as illustrated in Figure 4.1. The most salient feature of this constricted pore geometry is that an excess capillary pressure is built on the internal side of the downstream meniscus as the droplet enters the pore constriction because the radius of the left (upstream) meniscus R left is greater than the radius of the right meniscus R nght .…”