Study of Displacement Efficiency and Flow Behavior of Foamed Gel in Non-Homogeneous Porous Media

<div><p>Field trials have demonstrated that foamed gel is a very cost-effective technology for profile modification and water shut-off. However, the mechanisms of profile modification and flow behavior of foamed gel in non-homogeneous porous media are not yet well understood. In order to investigate these mechanisms and the interactions between foamed gel and oil in porous media, coreflooding and pore-scale visualization waterflooding experiments were performed in the laboratory. The results of the coreflooding experiment in non-homogeneous porous media showed that the displacement efficiency improved by approximately 30% after injecting a 0.3 pore volume of foamed gel, and was proportional to the pore volumes of the injected foamed gel. Additionally, the mid-high permeability zone can be selectively plugged by foamed gel, and then oil located in the low permeability zone will be displaced. The visualization images demonstrated that the <i>amoeba effect</i> and Jamin effect are the main mechanisms for enhancing oil recovery by foamed gel. Compared with conventional gel, a unique benefit of foamed gel is that it can pass through micropores by transforming into arbitrary shapes without rupturing, this phenomenon has been named the <i>amoeba effect</i>. Additionally, the stability of foam in the presence of crude oil also was investigated. Image and statistical analysis showed that these foams boast excellent oil resistance and elasticity, which allows them to work deep within formations.</p></div

Etched glass micromodel.

<p>Etched glass micromodel.</p

Visualized waterflooding.

<p>(a) Saturated by crude oil; (b) Displacing to residual saturation; (c) Before foamed gel treatment; (d) After foamed gel treatment.</p

Synthetic brine composition.

<p>Synthetic brine composition.</p

Schematic of micromodel apparatus.

<p>1-Micromodel; 2-Bottom light physical model chamber (iosthermal controllable); 3-Micro pump; 4-Video camera; 5-Computer.</p

Oil displacement test by injecting 0.3PV of foamed gel.

<p>Oil displacement test by injecting 0.3PV of foamed gel.</p

Comparison of foamed gel with conventional gel.

<p>Comparison of foamed gel with conventional gel.</p

Amoeba effect I.

<p>(a) Foamed gel distribution in micromodel; (b) Dumbbell-shaped foam; (c) Dumbbell-shaped foam; (d) Foamed gei distribution after placement.</p

Good oil resistance of foamed gel(magnified 300x).

<p>(a) Foaming trapping; (b) Oil film on foam surface.</p

Schematic of breakthrough-vacuum apparatus.

<p>Schematic of breakthrough-vacuum apparatus.</p