Application of Polymer Flooding in Systems with Varying Viscous/Gravity Ratio

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Polymer flooding is a well-established method for enhancing oil recovery, typically described as mobility control, whereby the polymer is used to increase the viscosity of the injected water (µw) to be closer to the oil viscosity (µo). More recently, viscous crossflow (VX) has been attributed as a key mechanism in the polymer flooding of more viscous oils (say µo >50m cP). We believe that this mechanism accounts for the very high recovery factors observed in highly adverse viscosity ratio systems. However, a second crossflow mechanism may also operate during polymer flooding when gravity is important (i.e. in water slumping). In such systems, the oil is in fact swept downwards into the underlying water channel prior to the sweep of the bypassed “attic” oil as the polymer re-balances the viscous-gravity forces. Indeed, this is also a type of VX mechanism, which was first reported some time ago by Goodyear et al (1995).

In this work, we show the strong potential of polymer flooding in gravity dominated systems to significantly accelerate oil production and access otherwise unattainable resources. The base data set extends previous work using the Captain reservoir, to study a wide range of oil and reservoir properties (density, reservoir thickness, inter-well distance, and injection rate) before exploring the potential for polymer flooding at significantly higher oil viscosities (412 cPs & 2,000 cP). Finally, systems with low oil viscosities and low densities are examined to establish the potential acceleration of oil in near “stable” displacement systems.

The results presented in this paper show that across many sensitivities, polymer flooding is extremely effective in accelerating production and reducing water production. As the viscous / gravity balance increases, much less water slumping occurs but vertical sweep can still be significantly improved by polymer flooding in heavy oil systems, where the water neither slumps nor fully contacts the upper reservoir. Most interestingly, polymer flooding shows acerated production at µo=4 mPa.s and even at near unity mobility secondary polymer flooding was able to accelerate oil production in homogeneous systems, while tertiary polymer flooding was effective in layered systems.

The work presented here demonstrates that polymer flooding can be effective across an extremely wide range of reservoirs, even those with near unity viscosity ratios. Polymer flooding goes beyond mobility control and is effective in overcoming gravity induced water slumping. Over the Energy Transition, there will still be a demand for oil which must be produced as efficiently as possible. This research shows polymer flooding can be applied to high viscosity, high density oils through to low viscosity, low density oils and accelerate the production with reduced water handling.
Original languageEnglish
Number of pages21
Publication statusPublished - 2 Oct 2023
EventIOR+ 2023 - The Hague, Netherlands
Duration: 2 Oct 20234 Oct 2023


ConferenceIOR+ 2023
CityThe Hague


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