Procedia Earth and Planetary Science最新文献

Amongst the existing models able to describe highly concentrated aqueous systems and solid-liquid or gas-liquid equilibria up to elevated temperatures and pressures, the semi-empirical Pitzer model has been shown to be powerful. Calculation codes are now available for applying this model to such complex natural and industrial systems. The key point remains the building of related thermodynamic databases of high quality. In this work, we present elements of a strategy to build and extend such a database for widespread use.

Solutions of different chemical compositions will precipitate gypsum crystals with different morphology. The dependence of gypsum morphology on the chemical composition can therefore be a tool for interpreting the paleo-chemistry and environments of solutions from which gypsum in the geological record precipitated. In addition, the morphology of the gypsum that will precipitate in the Dead Sea once the Red Sea-Dead Sea conduit is built will determine if the crystals will remain in suspension in the surface brine, thereby leading to “whitening” of the lake. Despite its importance, little is known about the impact of the different parameters on the morphology of gypsum precipitated from natural brines. In the present study we conducted single point batch experiments with mixtures of Dead Sea - Red Sea brines and utilized image processing techniques to study the morphology of the gypsum that precipitated from different solution compositions at different degrees of oversaturation. The results from the first data set towards the understanding of what controls the morphology of gypsum while providing a preliminary tool for the forecast of the future of the Dead Sea are presented here.

The present study of thermal water from Bad Bellingen, Steinenstadt, Bad Krozingen, Mooswald, and Weinheim located in the southern part of the Upper Rhine Graben was undertaken in the framework of a multidisciplinary hydrogeochemical research project and concerns ⁸⁷Sr/⁸⁶Sr isotope investigation. The aquifer lithologies of thermal waters are Triassic Upper Muschelkalk, Jurassic Hauptrogenstein and Tertiary Miocene sediments. The ⁸⁷Sr/⁸⁶Sr ratios (N=9) range from 0.70912 to 0.71096. The Sr isotopic composition of thermal water is controlled by the fault system of the Rhine Graben rift. Fluids from Upper Muschelkalk aquifers ascent along the Eastern Boundary fault zone. The deep-water ascent most likely reaches into the crystalline basement.

Water-quality and isotopic data were collected in central Nevada, USA in an exploration hydraulic fracturing area with no previous oil or gas production. The target shales of the Elko Formation are unique fresh-water hydrocarbon reservoirs with relatively dilute source water (8.5 g/L total dissolved solids [TDS]). Additionally, the Elko Formation is underlain by a fresh-water carbonate aquifer (0.2-0.3 g/L TDS) that outcrops downgradient of the exploration area. The water quality and isotopic data were used to evaluate pre-hydraulic fracturing conditions in this undeveloped area. The same data were also collected for groundwater and surface-water sites about two months and one year after exploration hydraulic fracturing. No systematic differences in water chemistry were observed between pre- and post-hydraulic fracturing samples. Based on water chemistry of shallow groundwater, surface water, and from the production zone, the most useful constituents identified for monitoring for potential future incursion of reservoir-associated fluids into the near-surface environment are TDS (or electrical conductivity), chloride, propane, methanol, ethanol, and 2-butoxyethanol. Groundwater flow and transport models were developed to evaluate the potential movement of hydrocarbons and hydraulic fracturing fluids from the targeted zones, which are about 1800 to 3600 m beneath the land surface, to shallow groundwater (<300 m below land surface). Model simulations indicate that hydraulic fracturing fluid remains contained within the target shales for at least 1,000 years for most development scenarios.