Procedure to determine the impact of the surface film resistance on the hygric properties of composite clay/fibre plasters

International audienc

Reactive transport experiments of coupled carbonation and serpentinization in a natural serpentinite. Implication for hydrogen production and carbon geological storage

Serpentinization and carbonation of ultramafic formations is a ubiquitous phenomenon, which deeply influences the biogeochemical cycles of water, hydrogen, carbon…while supporting the particular biosphere around the oceanic hydrothermal vents. Carbonation of peridotites and other mafic and ultramafic rocks is also a hot topic in the current energy landscape as the engineered sequestration of mineral CO2 in these formations could help reduce the atmospheric emissions and cope with climate change. In this study, we present two reactive percolation experiments performed on a natural serpentinite dredged from the ultraslow South-West Indian Oceanic Ridge. The serpentinite cores (length 3–4 cm and dia. 5.6 mm) were subjected for about 10 days to the continuous injection of a NaHCO3-saturated brine at respectively 160 °C and 280 °C. Petrographic and petrophysical results as well as outlet fluid compositions were compared to numerical batch simulations performed with the PHREEQC open software allowing to reconstruct the mineralogical evolution of both cores. The most striking observation is the fast and dramatic decrease of the permeability for both experiments principally due to the precipitation of carbonates. On the contrary, serpentine was found to be less impacting as it precipitates in low-flow zones, out of the main percolation paths. In total, about 5.6% of the total injected CO2 was retained in the core, at 280 °C. In the same time, hydrogen was consistently produced with a total recovered H2 corresponding to 0.8% of the maximum H2 possible. The global behavior of the cores is interpreted as the result from an interplay between interacting spatio-temporal lengthscales controlled by the Damköhler number

A NOVEL DEVICE FOR YARN PRESSURE VARIATION MEASUREMENT IN WILD WINDING

International audienc

Water-rock interactions and self-remediation: Lessons from a hydraulic fracturing operation in the Vaca Muerta formation, Argentina

International audienceIn order to analyze the effect of a new gelling agent for hydraulic fracturing, fluid samples from different stages of the operation (hydraulic fracturing fluid, coil tubing, flowback and produced waters) were collected from a well in the Vaca Muerta formation in Argentina. Collected samples were analyzed for major and trace elements, first within a few days after sampling, then reanalyzed 6 months later and again 2 years after sampling. Results show that the salinity of samples increased quickly with time, from 2000 mg/L up to 43,000 mg/l a month later, due to the mixing of hydraulic fracturing fluids with formation water. No evidence of water-rock reactions was observed. Results from the later analyses showed that the composition of the samples evolved with time with a sensible decrease of concentration for most trace elements over the course of these two years (e.g. Ba from 137 mg/L to 55 mg/L, Mn from 8 mg/L to 5 mg/L) and heavy metals (e.g. As /L to 1 f/L, Co /L to /L, Cr from /L to /L). Interpretation of the results shows that delayed, post-sampling, precipitation of barite in the preserved samples is the reason for such a decrease. This opens a very interesting option for mitigation and remediation of wastewaters from hydraulic fracturing as natural or even triggered precipitation of barite could involve most of the dissolved heavy metals and decrease strongly their concentrations