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First International Conference on Frontiers in Shallow Subsurface Technology
- Conference date: 20 Jan 2010 - 22 Jan 2010
- Location: Delft, Netherlands
- Published: 20 January 2010
41 - 48 of 48 results
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Visualization setup for the investigation of interfacial area for two-phase flow in a micro-model
Authors N.K. Karadimitriou, S.M. Hassanizadeh and P. KleingeldOne of the most challenging issues in the experimental investigation of interfacial area and its properties for two-phase flow in a micro-model is the visualization method. A micro-model is a micro-structure that represents a porous medium. The choice of the appropriate method depends on the dimensions of a micro-model and whether the experiments concern steady-state or dynamic effects. In the case of relatively small micro-models for steady-state or dynamic experiments, the use of a microscope in combination with a camera is the most effective method. When it comes to experiments where the micro-model is bigger than the optical frame of a microscope, the direct use of cameras is preferable. In this work, we present the visualization method for an elongated micro-model, with dimensions of the flow network of 1x10 mm2. The purpose of the experiment is the investigation of the role of fluid-fluid interfacial area in two-phase flow under dynamic conditions. Because of the dimensions of the micro-model, the use of a microscope is impossible without moving the micro-model. In our setup, four high resolution cameras with frame rate of 15 fps will be used. Each camera will cover an area of 1x1.7 mm2, thus a total area of 1x6.8 mm2 will be observed at any time. These cameras will record the distribution of phases. Then, with the aid of a computer and proper software, specific interfacial area and phase saturation will be determined as a function of time.
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Determination of longitudinal and transverse thermal dispersion coefficients in a fluid saturated porous medium
Authors Muhammad Imran and Ruud J. SchottingGeothermal energy is a clean and environment friendly renewable natural source of energy continuously produced inside the earth as a result of the decay of radioactive material. Hydrothermal energy from geothermal reservoirs is utilized by pumping the hot water from deeper formations to the surface by production wells and after heat extraction, it (cooled water) is injected back to the geological formation by injection wells for the maintenance of hydraulic regime, to avoid subsidence and for long term utilization of geothermal potential of the reservoir. The present work aims at the impact of both longitudinal and transverse thermal dispersion coefficients on heat transfer characteristics (Nusselt number, Rayleigh number, Pe) in forced convective flow in a layered (isotropic, heterogeneous) saturated porous medium numerically (FEM) by using one temperature model describing the thermal equilibrium between fluid and solid phases with volume averaging. We investigate the dependency of both thermal dispersion coefficients on fluid flow and properties by coupling the 2-D steady convection-conduction model with steady fluid flow. An important step is to specify the distance between the production and injection wells to avoid the entry of cool water into the production well.
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Borehole radar monitoring in shallow oilfield applications
Authors Mattia Miorali, Evert Slob and Rob ArtsWe use a 2D Finite-Difference-Time-Domain electromagnetic (EM) wave simulator to model a borehole radar system located in a shallow oilfield production environment. Main aim of this study is to investigate if radar technology is suitable for detecting and monitoring fluid saturation changes in the proximity of production wells. An analysis of the main constraints for an implementation of a radar system as permanent down-hole sensor has been performed. The main constraints are given by the conductivity of the formation and by the effect of the borehole casing on the emitted EM signal. An antenna shield is necessary to reduce the destructive interference between the emitted signal and the reflections by the metal parts of the wellbore. Moreover, different reservoir scenarios are considered. The heterogeneity of the background formation strongly affects the retrieval of the target reflections and gradual fluid saturation changes reduce the amount of the reflections.
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ATES-ThermoGIS: a dedicated web portal to boost the application of shallow geothermal energy in the Netherlands
Authors Hendrik J. Simmelink, Sterre Dortland and Rob A.A. van der KrogtIn order to expand Aquifer Thermal Energy Storage (ATES) into a substantial share within the current Dutch sustainable energy policy, it is necessary to boost the yearly growth of ATES systems from the current 10% to 30% in the next decade. To support this challenge, TNO and Deltares are developing the ThermoGIS web portal, an information and knowledge system for ATES systems. The web portal will provide various stakeholders of ATES, such as policy makers, spatial planners, project developers and city councils with regional-scale information on the potential of ATES in their area of interest. The information system is based on hydrogeological information of the Dutch subsurface that is translated into feasible thermal energy storage capacity of the aquifers. ThermoGIS directly shows whether design storage-system dimensions can be met. The web portal allows overlaying these conditions with other subsurface and geographical information, necessary for assessing limiting factors and risks, such as groundwater quality conditions, locations of groundwater protection zones and contaminated areas. Furthermore, it will also accommodate assessment of various legal criteria for ATES. Hence, the portal system seamlessly meets the requirements of a national ‘traffic light system’ for ATES as was recently recommended by the governmental ATES Task Force, aiming to diminish regulation and optimize technical implementation of ATES.
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A case study of electricity generation from low quality geothermal energy sources
Authors A. A. Eftekhari, T.J. Heimovaara and J. BruiningThis study investigates whether the low efficiency of electricity generation from low quality geothermal energy sources can be improved by using night sky radiation. Useful energy or work can be generated from a heat source when there is a temperature difference ΔT, e.g., between the heat source (T > T0) and a heat sink T0. It is also possible to have a low temperature heat "source" (T < T0) as long as the Carnot efficiency factor (T0-T)/T0 is sufficiently large. By way of example we use a geothermal energy plant from which a maximum of useful energy (electricity) is to be extracted. We only give a schematic exergy analysis of geothermal energy extraction, which includes the exergy necessary for circulating water and material costs for a 20-year project. The useful energy produced is calculated using a device that contains series of Peltier elements that are exposed on one side to the produced hot water and on the other side to a vessel loosing heat to the night sky. The result is compared to a similar device where the cold side assumes an ambient temperature of 10o C. As expected, the process using night cooling is the more efficient process, but the present efficiency of Peltier elements is insufficient for an exergetically viable electricity production. It turns out that the use of night sky radiation leads to about the same efficiency as groundwater cooling.
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Cleaning tar deposits by diluted air combustion
Authors A.A. Mailybaevz, J. Bruining, D. Marchesin, S. Rudolph and T.J. HeimovaaraWe study one-dimensional flows possessing a combustion wave when air is injected into the porous medium filled with high viscosity non aqueous phase liquids (VNAPL), medium viscosity oil, light oil and water. The polluting VNAPL is burnt and the water is vaporized, we describe combustion regimes in the form of a sequence of travelling waves and derive formulae for parameters in these waves. We show that there are combustion regimes in which VNAPL or oxygen is partially consumed in combustion as well as a regime in which both VNAPL and oxygen are consumed completely. Explicit conditions for each combustion regime are given.
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Exploring the shallow subsurface of the North Sea
Authors Edwin Tervoort and Joek PeuchenThe beach is no longer the frontier of human activity. The shallow subsurface in the North Sea, for example, is used by numerous industries (Figure 1). The North Sea seabed is the site of communication and electricity transfer cables; pipelines that transport hydrocarbons, water and waste; military exercises and munitions dumps; sand extraction (currently over 25 million m3/year); and platforms, windmills and other structures for extracting and harnessing energy sources. Some areas have been set aside for ecological and historical resource preservation, but most of the sea will become ‘busier’ and more crowded as existing offshore industrial activities expand and new uses are introduced. New uses of the North Sea may be geothermal energy production, artificial islands for airports and energy, a network of electricity interconnectors, CO2 storage, and harnessing tides to produce electricity. All these activities, even those associated with ships and floating structures, require structures that are based on and interact with the shallow subsurface: they all require ‘foundations.’
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Imaging frozen glacio-fluvial bedrock valley infill using Ground Penetrating Radar
Authors Michael Afanasyev, J.E.A. Stormss and I.L. de WinterA Ground Penetrating Radar (GPR) survey was conducted in April of 2008, in Sandflugtdalen, a permafrosted glaciofluvial bedrock valley in West Greenland. GPR has good depth penetration of permafrost, up to 80 m using low-frequency (50 MHz) antennae. Data has been processed to improve resolution and visibility of reflections from subsurface structures. Using the principles of radar stratigraphy, radar facies, surfaces and packages are identified in the dataset. Average bedrock depth in Sandflugtdalen is 50 meters. Bedrock barriers, overlaid by push moraines, divide Sandflugtdalen in 3 subbasins. Sediment volume in the mapped area is estimated as 0.37 km3. Modeling the bedrock and mapping the sedimentary architecture in a filled glacial valley generates a base-case for model validation of short-term climate changes and effects on glacier and sedimentary system.
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