Eric Mackay

Heriot-Watt University

Inter-phase component transfer from EOR to CCUS applications

Compositional reservoir simulators, such as GEM, are used to model component transport in oleic, gaseous and aqueous phases.  The distribution of these components within each grid block is used, together with pressure and temperature, to determine physical properties of the carrier phases that impact flow, such as viscosity and density.  In many EOR and CCUS applications, it is also important to calculate the mutual solubility of components in multiple solvents, and the transfer of components and heat between phases.  We discuss EOR and CCUS applications where inter-phase component transfer is important, and identify where learnings can be shared between both applications.

Interactions between liquid phases and the reservoir rock may be important, such as heat exchange and geochemical reactions such as dissolution, precipitation, ion exchange, etc.  Here we primarily address component transfer between fluid phases, focussing on components that are soluble in the aqueous and non-aqueous phases, such as CO2, H2S, CH1, H2O and H2, and on heat transfer.  Partitioning of CO2 and lighter end hydrocarbon components between gaseous and oleic phases has been extensively studied in terms of impact on hydrocarbon mobilisation during EOR, including subtle effects such as impact of viscous crossflow.  CO2 dissolution in the aqueous phase is also recognised as an important trapping mechanism during CCUS; here we introduce its impact on plume migration velocities in aquifers subject to even modest background drift fluxes.  During waterflooding of oil reservoirs, partitioning of CO2 from the oleic to the aqueous phase can impact near injection well geochemistry, until such time as a CO2 desaturated front has propagated away from the well.  This is further complicated by the thermal front, which propagates more slowly than the saturation front, but impacts CO2 solubilities.  Key to all these processes is the speed with which various fronts propagate through the porous medium.