Impact of drilling mud on chemistry and microbiology of an Upper Triassic groundwater after drilling and testing an exploration well for aquifer thermal energy storage in Berlin (Germany)

After completion of an exploration well, sandstones of the Exter Formation were hydraulically tested to determine the hydraulic properties and to evaluate chemical and microbial processes caused by drilling and water production. The aim was to determine the suitability of the formation as a reservoir for aquifer thermal energy storage. The tests revealed a hydraulic conductivity of 1–2 E-5 m/s of the reservoir, resulting in a productivity index of 0.6–1 m³/h/bar. A hydraulic connection of the Exter Formation to the overlaying, artesian “Rupelbasissand” cannot be excluded. Water samples were collected for chemical and microbiological analyses. The water was similarly composed as sea water with a maximum salinity of 24.9 g/L, dominated by NaCl (15.6 g/L Cl and 7.8 g/L Na). Until the end of the tests, the water was affected by drilling mud as indicated by the high pH (8.9) and high bicarbonate concentration (359 mg/L) that both resulted from the impact of sodium carbonate (Na₂CO₃) additives. The high amount of dissolved organic matter (>?58 mg/L) and its molecular-weight distribution pattern indicated that residues of cellulose, an ingredient of the drilling mud, were still present at the end of the tests. Clear evidence of this contamination gave the measured uranine that was added as a tracer into the drilling mud. During fluid production, the microbial community structure and abundance changed and correlated with the content of drilling mud. Eight taxa of sulfate-reducing bacteria, key organisms in processes like bio-corrosion and bio-clogging, were identified. It can be assumed that their activity will be affected during usage of the reservoir.     

CHEMICAL CHARACTERISTICS OF WETLAND′S INFLOW DRY DIFFUSE DUST AND DIRT FROM IMPERVIOUS SURFACE

1INTRODUCTIONIn impervious area dry dustand dirtbuildup con-tains heavy metals,nutrients,pesticides and organ-ics.Many studies(APWA,1969;Sartor and Boyd,1972;Pitt and Amy,1973;Pitt,1979,1985;Yousef and Wanielista,1990;Wanielista andYousef,1993,Ball,et al.…     

FRW bulk viscous cosmology with modified cosmic Chaplygin gas

In this paper we study FRW bulk viscous cosmology in presence of modified cosmic Chaplygin gas. We obtain generalized Friedmann equations due to bulk viscosity and modified cosmic Chaplygin gas. Then, we calculate time-dependent energy density and discuss Hubble expansion parameter.     

Land use and land cover classification over a large area in Iran based on single date analysis of satellite imagery

Accelerated soil erosion, high sediment yields, floods and debris flow are serious problems in many areas of Iran, and in particular in the Golestan dam watershed, which is the area that was investigated in this study. Accurate land use and land cover (LULC) maps can be effective tools to help soil erosion control efforts. The principal objective of this research was to propose a new protocol for LULC classification for large areas based on readily available ancillary information and analysis of three single date Landsat ETM+ images, and to demonstrate that successful mapping depends on more than just analysis of reflectance values. In this research, it was found that incorporating climatic and topographic conditions helped delineate what was otherwise overlapping information. This study determined that a late summer Landsat ETM+ image yields the best results with an overall accuracy of 95%, while a spring image yields the poorest accuracy (82%). A summer image yields an intermediate accuracy of 92%. In future studies where funding is limited to obtaining one image, late summer images would be most suitable for LULC mapping. The analysis as presented in this paper could also be done with satellite images taken at different times of the season. It may be, particularly for other climatic zones, that there is a better time of season for image acquisition that would present more information.     

Investigation of spatio-temporal patterns of seasonal streamflow droughts in a semi-arid region

Natural Hazards - Spatio-temporal patterns of seasonal streamflow droughts were investigated for the semi-arid Karkheh watershed, located in western Iran with an area of 41,470 km2,...     

Landform classification from a digital elevation model and satellite imagery

The Iranian Soil and Water Research Institute has been involved in mapping the soils of Iran and classifying landforms for the last 60 years. However, the accuracy of traditional landform maps is very low (about 55%). To date, aerial photographs and topographic maps have been used for landform classification studies. The principal objective of this research is to propose a quantitative approach for landform classification based on a 10-m resolution digital elevation model (DEM) and some use of an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image. In order to extract and identify the various landforms, slope, elevation range, and stream network pattern were used as basic identifying parameters. These are extractable from a DEM. Further, ASTER images were required to identify the general outline shape of a landform type and the presence or absence of gravel. This study encompassed a relatively large watershed of 451 183 ha with a total elevation difference of 2445 m and a variety of landforms from flat River Alluvial Plains to steep mountains. Classification accuracy ranged from 91.8 to 99.6% with an average of 96.7% based upon extensive ground-truthing. Since similar digital and ASTER image information is available for Iran, an accurate landform map can now be produced for the whole country. The main advantages of this approach are accuracy, lower demands on time and funds for field work and ready availability of required data for many regions of the world.     

Effects of excitation frequency on detection accuracy of orthogonal wavelet decomposition for structural health monitoring

Accurate estimation of stiffness loss is a challenging problem in structural health monitoring. In this study orthogonal wavelet decomposition is used for identifying the stiffness loss in a single degree of freedom spring-mass-damper system. The effects of excitation frequency on accuracy of damage detection is investigated. Results show that pseudo-alias effects caused by the orthogonal wavelet decomposition (OWD), affect damage detectability. It is demonstrated that theproposed approach is sunable for damage detection when the excitation frequency is relatively low. This study shows how a priori knowledge about the signal and ability to control the sampling frequency can enhance damage detectability.     

A moving‐mesh finite‐volume method to solve free‐surface seepage problem in arbitrary geometries

The main objective of this work is to develop a novel moving‐mesh finite‐volume method capable of solving the seepage problem in domains with arbitrary geometries. One major difficulty in analysing the seepage problem is the position of phreatic boundary which is unknown at the beginning of solution. In the current algorithm, we first choose an arbitrary solution domain with a hypothetical phreatic boundary and distribute the finite volumes therein. Then, we derive the conservative statement on a curvilinear co‐ordinate system for each cell and implement the known boundary conditions all over the solution domain. Defining a consistency factor, the inconsistency between the hypothesis boundary and the known boundary conditions is measured at the phreatic boundary. Subsequently, the preceding mesh is suitably deformed so that its upper boundary matches the new location of the phreatic surface. This tactic results in a moving‐mesh procedure which is continued until the nonlinear boundary conditions are fully satisfied at the phreatic boundary. To validate the developed algorithm, a number of seepage models, which have been previously targeted by the other investigators, are solved. Comparisons between the current results and those of other numerical methods as well as the experimental data show that the current moving‐grid finite‐volume method is highly robust and it provides sufficient accuracy and reliability. Copyright © 2007 John Wiley & Sons, Ltd.     

Alteration of fluid properties during the initial operation of a geothermal plant: results from in situ measurements in Groß Schönebeck

Recently, the thermal fluid loop has been established and continuosly operated for 7 days at the geothermal in situ laboratory in Groß Schönebeck (North German Basin). During this initial phase of fluid production, the fluid temperature, measured at the surface, continuously increased until a stable value of about 98 °C was established. Fluid physicochemical properties (pH, redox, density, temperature, and pressure) were measured online and in situ with a newly developed fluid monitoring system (FluMo). Additionally, fluid samples have been collected at various temperatures (in 5–10 °C steps) directly at the production well at about 10 bar pressure. From the pressurized sampling tool, the fluid was directly transferred into a heated autoclave, which allowed filtration (0.2 μm) in the absence of oxygen. Physicochemical parameters [pH, redox, electric conductivity, total dissolved solids (TDS)] as well as acid capacity (K _S 4.3) of these samples have been measured onsite at atmospheric conditions. Concentrations of anions, total organic carbon, and metals were analyzed later in the laboratory. Both, measurements in collected samples or in situ (FluMo) analysis of most the parameters density, electric conductivity, or TDS indicated relatively constant values over the whole production time (1.17–1.18 g · cm^?3, 215–221 mS · cm^?1, 241–260 g · L^?1, respectively). Good correlation was also found for pH values (pH = 6.6–6.9), whereas the redox values varied between ?1 and 46 mV when determined at 25 °C and decreased strongly when measured in situ with increasing temperature (?110 mV at 90 °C). The elemental composition of collected samples remained also relatively constant for most compounds and was clearly higher as compared with samples collected in 2011. Results of this study demonstrate that realistic, comprehensive, and time-resolved physicochemical data can be obtained by FluMo. These detailed data sets can be crucial to understand the complex geochemical processes in a thermal water loop and eventually to take required measures on time.     

Thermal–hydraulic measurements and modelling of the brine circuit in a geothermal well

Wellhead temperature and pressure are critical parameters of a geothermal well. Their prediction requires knowledge of the geofluid properties and detailed thermal modelling of the well and formation. High salinity and gas content complicate the task. This article presents a comprehensive thermal–hydraulic wellbore model, which is parameterized and validated with data from the Gross Schoenebeck site, and used for a long-term prognosis. Geofluid properties are calculated based on the specific gas and salt contents by determining the vapour–liquid equilibrium.