An experimental feasibility study on the use of CO2-soluble polyfluoroacrylates for CO2 mobility and conformance control applications

https://doi.org/10.1016/j.petrol.2019.106556Get rights and content

Highlights

  • CO2-soluble polyfluoroacrylates (PFA) can thicken CO2 at reservoir conditions.

  • However, CO2 + PFA solutions are unsuitable for mobility control due to adsorption.

  • PFA adsorption induces significant permeability reduction, especially in sandstone.

  • Dual parallel core tests show that CO2 + PFA solutions provide conformance control.

Abstract

High molecular weight polyfluoroacrylate (PFA) is an amorphous, sticky, hydrophobic, oil-phobic, CO2-soluble homopolymer. 1 wt% PFA-in-CO2 solutions are four times as viscous as pure CO2. Although these solutions provided modest mobility control, unexpectedly large increases in pressure drop occurred because a portion of the PFA adsorbed onto the pore surfaces, altering wettability and significantly permeability. Further, PFA exhibited diminished solubility in CO2 in the presence of light extracted hydrocarbons. Although these effects rendered CO2-PFA solutions inappropriate for mobility control, excellent conformance control for dual parallel brine-saturated cores was attained when a CO2-PFA solution was first injected into the isolated high permeability sandstone core. This core was then placed in parallel with a low permeability sandstone core, and all of the subsequently injected CO2 was diverted to the low permeability core. Conformance control was not as effective in limestone, possibly due the low pH-induced erosion of the limestone that mitigated PFA adsorption.

Keywords

CO2 enhanced oil recovery
Polyfluoroacrylate
Mobility control
Conformance control
Polymer adsorption

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