CO2 wettability of seal and reservoir rocks and the implications for carbon geo-sequestration

We review the literature data published on the topic of CO2 wettability of storage and seal rocks. We first introduce the concept of wettability and explain why it is important in the context of carbon geo-sequestration (CGS) projects, and review how it is measured. This is done to raise awareness of this parameter in the CGS community, which, as we show later on in this text, may have a dramatic impact on structural and residual trapping of CO2. These two trapping mechanisms would be severely and negatively affected in case of CO2-wet storage and/or seal rock. Overall, at the current state of the art, a substantial amount of work has been completed, and we find that: 1. Sandstone and limestone, plus pure minerals such as quartz, calcite, feldspar, and mica are strongly water wet in a CO2-water system. 2. Oil-wet limestone, oil-wet quartz, or coal is intermediate wet or CO2 wet in a CO2-water system. 3. The contact angle alone is insufficient for predicting capillary pressures in reservoir or seal rocks. 4. The current contact angle data have a large uncertainty. 5. Solid theoretical understanding on a molecular level of rock-CO2-brine interactions is currently limited. 6. In an ideal scenario, all seal and storage rocks in CGS formations are tested for their CO2 wettability. 7. Achieving representative subsurface conditions (especially in terms of the rock surface) in the laboratory is of key importance but also very challenging

Experimental investigation into the sealing capability of naturally fractured shale caprocks to supercritical carbon dioxide flow

Geological storage of CO is considered a solution for reducing the excess CO released into the atmosphere. Low permeability caprocks physically trap CO injected into underlying porous reservoirs. Injection leads to increasing pore pressure and reduced effective stress, increasing the likelihood of exceeding the capillary entry pressure of the caprocks and of caprock fracturing. Assessing on how the different phases of CO flow through caprock matrix and fractures is important for assessing CO storage security. Fractures are considered to represent preferential flow paths in the caprock for the escape of CO. Here we present a new experimental rig which allows 38 mm diameter fractured caprock samples recovered from depths of up to 4 km to be exposed to supercritical CO (scCO) under in situ conditions of pressure, temperature and geochemistry. In contrast to expectations, the results indicate that scCO will not flow through tight natural caprock fractures, even with a differential pressure across the fractured sample in excess of 51 MPa. However, below the critical point where CO enters its gas phase, the CO flows readily through the caprock fractures. This indicates the possibility of a critical threshold of fracture aperture size which controls CO flow along the fracture

Brine/CO

It has been long recognized that interfacial interactions (interfacial tension, wettability, capillarity and interfacial mass transfer) govern fluid distribution and behaviour in porous media. Therefore the interfacial interactions between CO2, brine and reservoir oil and/or gas have an important influence on the effectiveness of any CO2 storage operation. There is a lack of experimental data related to interfacial properties for all the geological storage options (oil & gas reservoirs, coalbeds, deep saline aquifers). In the case of deep saline aquifers, there is a gap in data and knowledge of brine-CO2 interfacial properties at storage conditions. More specifically, experimental interfacial tension values and experimental tests in porous media are necessary to better understand the wettability evolution as a function of thermodynamic conditions and it’s effects on fluid flow in the porous media. In this paper, a complete set of experimental values of brine-CO2 Interfaciale Tension (IFT) at pressure, temperature and salt concentration conditions representative of those of a CO2 storage operation. A correlation is derived from experimental data published in a companion paper [Chalbaud C., Robin M., Lombard J.-M., Egermann P., Bertin H. (2009) Interfacial Tension Measurements and Wettability Evaluation for Geological CO2 Storage, Adv. Water Resour. 32, 1, 1-109] to model IFT values. This paper pays particular attention to coreflooding experiments showing that the CO2 partially wets the surface in a Intermediate-Wet (IW) or Oil-Wet (OW) limestone rock. This wetting behavior of CO2 is coherent with observations at the pore scale in glass micromodels and presents a negative impact on the storage capacity of a given site

High Pressure X-ray Diffraction Study on Phase Transitions of CuInTez₂

CuInTe2 is a ternary semiconductor that crystallize in the chalcopyrite structure of space group I4̄2d. X-ray diffraction measurements up to 30 GPa were carried out on this material at the energy dispersive station DW11 of the LURE-Orsay, France. A phase transition was observed at 5.9 GPa and this high pressure phase have been indexed as cubic NaCl-type estructure. The bulk moduli are 62 GPa for the chalcopyrite phase and 85 GPa for the cubic phase. The volume reduction at the transition pressure is about 9.8 % </jats:p

Cromatografia de troca-iônica aplicada ao isolamento da fração ácida do óleo de copaíba (Copaifera multijuga) e da sacaca (Croton cajucara)

Plant extracts are usually complex mixtures which contain several molecules of different sizes with varied functional groups. Such extracts are a challenge to the chemist of natural products. Ion exchange chromatography in non-aqueous medium, used for separation of basic or acidic fractions from plant extracts, is an important unit operation in preparative scale separations. Anionic macroporous resin in non-aqueous medium was used with success in this study for separation of the acid fraction of Copaifera multijuga (Copaiba oil), rich in labdanic diterpenes and for the methanolic extract of Croton cajucara (acetyl aleuritoric acid)