Adsorption Kinetics of Hydrolysed Polyacrylamide and its Impact on Laboratory Testing and Field Performance

Célia Silva, Alan Beteta, Katherine McIver, Kenneth Stuart Sorbie

Research output: Contribution to conferencePaper


Polymer flooding is one of the most mature enhanced oil recovery (EOR) techniques, where the injection water viscosity is increased through addition of a high molecular weight polymer. This results in a lower viscosity contrast between the displacing water phase and the displaced oil phase leading to a more efficient oil displacement. In field operations, one of the most critical parameters for successful polymer flooding is the polymer adsorption. During transport the polymer will irreversibly adsorb onto the reservoir, with the extent of adsorption depending on various factors, such as the polymer chemistry, reservoir mineralogy, brine composition, temperature etc. For a given application, there will be an upper limit of adsorption above which the polymer concentration will be significantly depleted, leading to either a diminished EOR performance or a requirement to increase the polymer concentration.

Polymer flooding has predominately used hydrolysed polyacrylamide (HPAM) to viscosify the injection water. In this work, it is demonstrated that there is a large kinetic component to the adsorption of HPAM on silica sand. While an adsorption of ∼24 µg/g was measured after 24 hours, this increased continuously over 14 days to a plateau of ∼110 µg/g. This behaviour is shown to be present at a range of concentrations under both aerobic and anaerobic conditions. To the authors knowledge, the kinetic adsorption of HPAM and its impact both on lab experiments and field polymer flooding has not been very extensively discussed in the literature.

From our experimental measurements of HPAM kinetic (and equilibrium) adsorption, a series of both core and field scale numerical simulations are carried out to demonstrate the potential impact of this relatively slow polymer kinetics at each length and time scale. At the core scale, we demonstrate that flooding at quite normal experimental rates may lead to significant underestimates of the true level of equilibrium polymer adsorption. In the reservoir, where residence time is much greater than 14 days, the polymer adsorption can reach kinetic equilibrium resulting in significantly retarded propagation of the polymer front, and hence the oil bank, and a requirement to overdose lower concentration polymer floods.

The ability to accurately plan polymer flooding projects is essential to fully optimise recovery performance as efficiently as possible, minimise the environmental footprint and reliably predict polymer breakthrough for production chemistry requirements. Thus, a complete understanding of the polymer adsorption and adsorption kinetics is critical for continued development of polymer EOR.
Original languageEnglish
Number of pages25
Publication statusPublished - 2 Oct 2023
EventIOR+ 2023 - The Hague, Netherlands
Duration: 2 Oct 20234 Oct 2023


ConferenceIOR+ 2023
CityThe Hague


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