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CO2 Dissolution Trapping Rates in Heterogeneous Porous Media – Kieran Gilmore

The rate of carbon dioxide (CO2) dissolution in saline aquifers is the least well‐constrained of the secondary trapping mechanisms enhancing the long‐term security of geological carbon storage. CO2 injected into a heterogeneous saline reservoir will preferentially travel along high permeability layers increasing the CO2 ‐water interfacial area which increases dissolution rates. We provide a conservative, first‐principles analysis of the quantity of CO2 dissolved and the rate at which free‐phase CO2 propagates in layered reservoirs. At early times, advection dominates the propagation of CO2 . This transitions to diffusion dominated propagation as the interfacial area increases and diffusive loss slows propagation. As surrounding water‐filled layers become CO2 saturated, propagation becomes advection dominated. For reservoirs with finely bedded strata, ∼10% of the injected CO2 can dissolve in a year. The maximum fraction of CO2 that dissolves is determined by the volumetric ratio of water in low permeability layers and CO2 in high permeability layers.

Studying Organic Friction Modifiers in Tribological Contacts with Neutron and X-ray Reflectometry – Sandy Armstrong

Organic Friction Modifiers (OFMs) are fatty amphiphilic molecules which are used to enhance lubricant oils, improving vehicle efficiency, and lowering CO2 emissions. OFM mode of action is thought to involve their adsorption at metallic surfaces, where they form compact surface films. Films on contacting metallic surfaces are believed to form planes of low shear resistance between the opposing surfaces, thereby reducing friction. The true nature of the OFM operating mechanism remains obscure as probing interfacial structures formed under tribological conditions is experimentally challenging.

To understand the interfacial behaviour of OFMs under shear at elevated temperatures and pressures, a novel tribometer rig has been developed that enables the in-situ study of surfactants in tribological contacts with neutron and X-ray reflectometry. Both techniques can probe the interface without significant perturbation to the system and can resolve structures with nanometre resolution. Results collected with the tribometer at shear rates of up to 3000 s-1 will be presented and discussed, with an emphasis on modelling the data.

This talk is part of the BPI Seminar Series series.

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