Experimental Study of Cement - Sandstone/Shale - Brine - CO2 Interactions

Background

Reactive-transport simulation is a tool that is being used to estimate long-term trapping of CO₂, and wellbore and cap rock integrity for geologic CO₂ storage. We reacted end member components of a heterolithic sandstone and shale unit that forms the upper section of the In Salah Gas Project carbon storage reservoir in Krechba, Algeria with supercritical CO₂, brine, and with/without cement at reservoir conditions to develop experimentally constrained geochemical models for use in reactive transport simulations.

Results

We observe marked changes in solution composition when CO₂ reacted with cement, sandstone, and shale components at reservoir conditions. The geochemical model for the reaction of sandstone and shale with CO₂ and brine is a simple one in which albite, chlorite, illite and carbonate minerals partially dissolve and boehmite, smectite, and amorphous silica precipitate. The geochemical model for the wellbore environment is also fairly simple, in which alkaline cements and rock react with CO₂-rich brines to form an Fe containing calcite, amorphous silica, smectite and boehmite or amorphous Al(OH)₃.

Conclusions

Our research shows that relatively simple geochemical models can describe the dominant reactions that are likely to occur when CO₂ is stored in deep saline aquifers sealed with overlying shale cap rocks, as well as the dominant reactions for cement carbonation at the wellbore interface.     

细胞自动生成破裂模型中非均质性对破裂形成的影响

岩石破裂是个复杂的过程，它一般涉及到破裂过程的复杂性和多样性，以及材料的非均生。因此，必然要采用理论方法建立破裂模型。本文根据破裂系统的基本物理特征，充分考虑点阵要素的非均质性，试图遵循一定规则来建立破裂模型，模拟控制地震形成的破裂过程。     

Endocrine disruption in a marine amphipod? Field observations of intersexuality and de-masculinisation

Intersexuality has been found in both males and females of the marine/estuarine amphipod, Echinogammarus marinus, at polluted and reference sites in East Scotland. Polluted sites had significantly more intersex specimens than reference sites, however the cause of intersexuality is unclear. Discriminant analysis of morphometric data showed that normal male specimens from the most polluted site resembled pooled intersex males, suggesting that subtle endocrine disruption (ED) maybe occurring in these otherwise apparently normal males. The main discriminating character was gnathopod size, recognised to be under androgenic gland control. The association of distinctive morphometry with intersexuality may provide a new approach to biomarkers of ED in crustaceans. The opportunities for other novel biomarkers, for example biochemical or behavioural markers, may also be explored through study of intersex animals.     

Population and resources in Mauritius

"The island of Mauritius was facing a crisis by the 1950s as the relationship between its population and resources became unbalanced....A two-pronged strategy was set in place to change the relationship between population and resources. Firstly, an aggressive family-planning policy was established, reducing population growth. Secondly, the economy was diversified with tourism, financial services and, especially, manufacturing in the Mauritius Export Processing Zone, creating extra finance and resources. The changes have not been cost-free but Mauritius ends the century, not as a classic case of overpopulation, but more [as] a model micro-state that has overcome many population and resource problems, largely through its own efforts."     

Modelling the VUV emission spectrum of N2: preliminary results on the effects of rotational interactions on line intensities

A theoretical model of the excited singlet ungerade electronic states of the nitrogen molecule is presented. This work is an extension of a previous study (D. Stahel, M. Leoni and K. Dressler, J. Chem. Phys. 79, 2541-2558, 1983) with the addition of rotational interactions between states of different symmetry. These rotational interactions together with the homogeneous couplings frequently lead to extreme mixing of the states. This model is being used to analyse the high resolution vacuum ultraviolet emission spectrum which is currently being recorded photoelectrically. The ultimate goal of this work is the reliable interpretation of the low resolution emission spectra observed from planetary atmospheres, notably that of Titan, and the transitions assigned as being important in the Voyager 1 spectra of Titan are discussed in detail.     

Condensation and vaporization studies of CH3OH and NH3 ices: major implications for astrochemistry

In an extension of previously reported work on ices containing H2O, CO, CO2, SO2, H2S, and H2, we present measurements of the physical and infrared spectral properties of ices containing CH3OH and NH3. The condensation and sublimation behavior of these ice systems is discussed and surface binding energies are presented for all of these molecules. The surface binding energies can be used to calculate the residence times of the molecules on grain surfaces as a function of temperature. It is demonstrated that many of the molecules used to generate radio maps of and probe conditions in dense clouds, for example CO and NH3, will be significantly depleted from the gas phase by condensation onto dust grains. Attempts to derive total column densities solely from radio maps that do not take condensation effects into account may vastly underestimate the true column densities of any given species. Simple CO condensation onto and vaporization off of grains appears to be capable of explaining the observed depletion of gas phase CO in cold, dense molecular cores. This is not the case for NH3, however, where thermal considerations alone predict that all of the NH3 should be condensed onto grains. The fact that some gas phase NH3 is observed indicates that additional desorption processes must be involved. The surface binding energies of CH3OH, in conjunction with this molecule's observed behavior during warm up in H2O-rich ices, is shown to provide an explanation of the large excess of CH3OH seen in many warm, dense molecular cores. The near-infrared spectrum and associated integrated band strengths of CH3OH-containing ice are given, as are middle infrared absorption band strengths for both CH3OH and NH3.     

Detection of the 2165 inverse centimeter (4.619 micron) XCN band in the spectrum of L1551 IRS 5

We report the detection of a broad absorption band at 2165 cm-1 (4.619 microns) in the spectrum of L1551 IRS 5. New laboratory results over the 2200-2100 cm-1 wavenumber interval (4.55-4.76 microns), performed with realistic interstellar ice analogs, suggest that this feature is due to a CN-containing compound. We will refer to this compound as XCN. We also confirm the presence of frozen CO (both in nonpolar and polar matrices) through absorption bands at 2140 cm-1 (4.67 microns) and 2135 cm-1 (4.68 microns). The relative abundance of solid-state CO to frozen H2O is approximately 0.13 while the abundance of XCN seems comparable to that of frozen CO.