If the amount of foams reaches a certain level as the fluid migrates continuously, much of the foam will come together and generate great additional force to crude oil, this additional force can be transformed into displacing force to improve oil recovery.
Wang Y, Jin J, Bai B, Wei M
CC BY 4.0
<a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4451013/bin/pone.0128414.s004.mpg">S4 Video</a> from <cite style="font-style:normal">Wang Y, Jin J, Bai B, Wei M (2015). "<a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4451013">Study of Displacement Efficiency and Flow Behavior of Foamed Gel in Non-Homogeneous Porous Media</a>". <i>PLOS ONE</i>. <a href="https://en.wikipedia.org/wiki/Digital_object_identifier" class="extiw" title="w:Digital object identifier">DOI</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1371/journal.pone.0128414">10.1371/journal.pone.0128414</a>. <a href="https://en.wikipedia.org/wiki/PMID" class="extiw" title="w:PMID">PMID</a> <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pubmed/26030282">26030282</a>. <a href="https://en.wikipedia.org/wiki/PubMed_Central" class="extiw" title="w:PubMed Central">PMC</a>: <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4451013">4451013</a>.</cite>