Abstract Volcaniclastic rocks are commonly overlooked as reservoirs or seals in hydrocarbon plays because their compositions are variably unstable and reactive during burial diagenesis. This study investigated the petrography and petrophysical characteristics of 60 volcaniclastic and four siliciclastic samples from three Paleogene volcanic provinces – East Greenland, Faroe Islands and Ethiopia. The volcaniclastic samples have highly variable helium porosities (average 25.2%), but negligible total optical porosities (average 1.9%), implying reduced reservoir potential. The samples have, however, highly variable air permeabilities (average 11 mD), suggesting that they could make tight reservoirs. The permeabilities are related to either early calcite cements or the devitrification of volcanic glass. Mercury injection capillary pressure data were collected for a subset of 33 samples that at leakage/breakthrough saturations could, under near-surface conditions, hold oil column heights of between 4 and 1181 m (average 240 m). The best seals consistently have zeolite contents of >20 vol% owing to their small pore throat radii. Conversely, the worst seals are dominated by smectite and a conspicuous absence of zeolite minerals. The zeolite-rich volcaniclastic rocks could, therefore, make good shallow seals. These features also apply to CO 2 storage, but questions remain about the reactivity of the volcanic material and secondary minerals with injected CO 2 , but also the adsorbent properties of zeolites, particularly clinoptilolite, in the presence of CO 2 .

Abstract Shale rocks are highly structurally and chemically heterogeneous, such that the pore structure–transport relationship is complex. Shales typically have porosity over many length-scales from the molecular up to macroscopic fractures. This work utilizes gas overcondensation to probe pore sizes from micropores to very large macropores all in the same experiment without the potential for damage due to high pressures when conducting mercury porosimetry. Indeed, the Bowland Shale samples studied here are generally inaccessible to mercury intrusion. The gas overcondensation method can also be augmented using scanning loops to assess the spatial juxtaposition of very different pore sizes, and this has been used to determine that some large macropores are shielded by pore necks less than 4 nm in size in the Bowland Shale. In addition, the adsorption calorimetry method has been used to assess the accessibility of the void space. It has been found that mass transport is limited by particular ‘hour-glass’-like pore necks that fill at quite low saturation, and thus present a barrier to molecular migration. The shielding of macroporosity by narrow necks was particularly significant for the Above Marine Band sample, with lower shielding observed in the Marine Band and Below Marine Band materials.

Abstract Using MESSENGER Mercury Dual Imaging System data, we produced three new maps of Sibelius Crater, Mercury. Geomorphological and spectral maps were combined into a single hybrid map containing units associated with ejecta deposits, crater floor landforms and impact melt ponding. Spatial measurement of these units shows that ∼50% of the mapped melt pond area lies within a large, degraded impact crater (crater B), beyond the significantly lower northern Sibelius rim, with a potential melt flow to a smaller, degraded impact structure further north (crater C). Freshly processed spectral data from the eight-colour Map Projected Multispectral Reduced Data Record data highlight the emplacement of multiple uplifted ejecta units with distinct spectral properties. A new, high-resolution digital elevation model was created to help define and analyse crater floor uplift features and disrupted crater rims and to create detailed cross-sections. These illustrate a proposed location of B's central uplift structure exposed in the northern wall slopes of Sibelius. Small features at the limit of visibility, such as a groove possibly associated with a rolling or sliding mega-boulder and lobate melt flow on the crater floor with accompanying channel opening, are highlighted for future investigations by BepiColombo's instruments once it reaches orbit.