Diagenesis and Formation Stress in Fracture Conductivity of Shaly Rocks; Experimental-Modelling Approach in CO2-Rock Interactions

In large scale subsurface injection of carbon dioxide (CO2) as obtainable in carbon sequestration programs and in environmentally friendly hydraulic fracturing processes (using supercritical CO2), long term rock-fluid interaction can affect reservoir and seal rocks properties which are essential in monitoring the progress of these operations. The mineralogical components of sedimentary rocks are geochemically active particularly under enormous earth stresses, which generate high pressure and temperature conditions in the subsurface. While geomechanical properties such as rock stiffness, Poisson’s ratio and fracture geometry largely govern fluid flow characteristics in deep fractured formations, the effect of mineralization can lead to flow impedance in the presence of favorable geochemical and thermodynamic conditions. Simulation results suggested that influx-induced mineral dissolution/precipitation reactions within clay-based sedimentary rocks can continuously close micro-fracture networks, though injection pressure and effective-stress transformation first rapidly expand the fractures. This experimental modelling research investigated the impact of in-situ geochemical precipitation at 50°C and 1,000 psi on conductivity of fractures under geomechanical stress conditions. Geochemical analysis were performed on different samples of shale rocks, effluent fluid and recovered precipitates both before and after CO2-brine flooding of crushed shale rocks at high temperature and pressure conditions. Bulk rock geomechanical hardness was determined using micro-indentation. Differential pressure drop data across fractured composite core were also measured with respect to time over a five a day period. This was used in estimating the conductivity of the fractured core. Three experimental runs per sample type were carried out in order to check the validity of observed changes. The results showed that most significant diagenetic changes in shale rocks after flooding with CO2-brine reflect in the effluent fluid with calcium based minerals dissolving and precipitating under experimental conditions. Major and trace elements in the effluent fluid (using ICP-OES analysis) indicated that multiple geochemical reactions are occurring with almost all of the constituent minerals participating. The geochemical composition of precipitates recovered after the experiments showed diagenetic carbonates and opal (quartz) as the main constituents. The bulk rock showed little changes in composition except for sharper peaks on XRD analysis, suggesting that a significant portion of amorphous content of the rocks have been removed via dissolution by the slightly acid CO2-brine fluid that was injected. However total carbon (TOC) analysis showed a slight increase in carbon content of the bulk rock. Micro-indention results suggested a slight reduction in the hardness of the shale rocks and this reduction appear dependent on quartz content. The differential pressure drop, its 1st derivative and estimated fracture conductivity suggests that reactive transport of dissolved minerals can possibly occlude fracture flow path at varying degree depending on equivalent aperture width, thereby improving caprock integrity with respect to leakage risks under CO2 sequestration conditions. An exponential-natural logarithm fit of the fracture conductivity can be obtained and applied in discrete fracture network modelling. The fit yielded lower and upper boundary limits for fracture conductivity closure. Higher temperature and pressure conditions of experimental investigations may be needed to determine the upper limit of shale rock seal integrity tolerance, under conditions that are similar to sequestration of CO2 into deep and hot sedimentary rocks

The histological appearance of the proximal aspect of the dorsal condylar sagittal ridge of the third metacarpal and metatarsal bone in young Warmblood horses: normal appearance and correlation with detected radiographic variations

The objective of this study is to describe the normal histological appearance of the dorsoproximal aspect of the sagittal ridge of the third metacarpal/metatarsal bone in young Warmblood horses, and to compare it to the different radiographic variations (irregular, indentation, lucency, notch) described at this level. A total of 25 metacarpo/metatarsophalangeal joints of 12 Warmblood horses were used. Five samples of each radiographically described group were selected for histological processing. Each category was compared with the normal control group. Each group showed a bone cortex, covered by hyaline cartilage and longitudinally aligned collagen fibres covered by loosely organized connective tissue proximally. The normal and irregular group showed a smooth bone cortex. In the indentation and lucency group, a depression in the cortex was detected. The notch group presented an expansion of the cortex. The collagen fibres and connective tissue were located in the depression in the indentation group whereas the location varied in the lucency and notch group. The radiologic detected differences are translated into detectable histological differences. Further research is warranted to determine whether these variations are developmental or congenital and to evaluate their potential influence on the joint function during hyperextension

Microstructural development during the quenching and partitioning process in a newly designed low-carbon steel

This paper presents a detailed characterization of the microstructural development of a new quenching and partitioning (Q&P) steel. Q&P treatments, starting from full austenitization, were applied to the developed steel, leading to microstructures containing volume fractions of retained austenite of up to 0.15. The austenite was distributed as films in between the martensite laths. Analysis demonstrates that, in this material, stabilization of austenite can be achieved at significantly shorter time scales via the Q&P route than is possible via a bainitic isothermal holding. The results showed that the thermal stabilization of austenite during the partitioning step is not necessarily accompanied by a significant expansion of the material. This implies that the process of carbon partitioning from martensite to austenite occurs across low-mobility martensite–austenite interfaces. The amount of martensite formed during the first quench has been quantified. Unlike martensite formed in the final quench, this martensite was found to be tempered during partitioning. Measured volume fractions of retained austenite after different treatments were compared with simulations using model descriptions for carbon partitioning from martensite to austenite. Simulation results confirmed that the carbon partitioning takes place at low-mobility martensite–austenite interfaces.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.OLD Metals Processing, Microstructures and PropertiesOLD Surface and Interface Engineerin

SILAC-based proteome analysis of Starmerella bombicola sophorolipid production

Starmerella (Candida) bombicola is the biosurfactant-producing species that caught the greatest deal of attention in the academic and industrial world due to its ability of producing large amounts of sophorolipids. Despite its high economic potential, the biochemistry behind the sophorolipid biosynthesis is still poorly understood. Here we present the first proteomic characterization of S. bombicola for which we created a lys1 Delta. mutant to allow the use of SILAC for quantitative analysis. To characterize the processes behind the production of these biosurfactants, we compared the proteome of sophorolipid producing (early stationary phase) and nonproducing cells (exponential phase). We report the simultaneous production of all known enzymes involved in sophorolipid biosynthesis including a predicted sophorolipid transporter. In addition, we identified the heme binding protein Dap1 as a possible regulator for Cyp52M1. Our results further indicate that ammonium and phosphate limitation are not the sole limiting factors inducing sophorolipid biosynthesis

FLO1 is a variable green beard gene that drives biofilm-like cooperation in budding yeast

The budding yeast, Saccharomyces cerevisiae, has emerged as an archetype of eukaryotic cell biology. Here we show that S. cerevisiae is also a model for the evolution of cooperative behavior by revisiting flocculation, a self-adherence phenotype lacking in most laboratory strains. Expression of the gene FLO1 in the laboratory strain S288C restores flocculation, an altered physiological state, reminiscent of bacterial biofilms. Flocculation protects the FLO1 expressing cells from multiple stresses, including antimicrobials and ethanol. Furthermore, FLO1(+) cells avoid exploitation by nonexpressing flo1 cells by self/non-self recognition: FLO1(+) cells preferentially stick to one another, regardless of genetic relatedness across the rest of the genome. Flocculation, therefore, is driven by one of a few known "green beard genes,'' which direct cooperation toward other carriers of the same gene. Moreover, FLO1 is highly variable among strains both in expression and in sequence, suggesting that flocculation in S. cerevisiae is a dynamic, rapidly evolving social trait