scholarly journals Reservoir characterization of the Upper Jurassic geothermal target formations (Molasse Basin, Germany): role of thermofacies as exploration tool

2015 ◽  
Vol 3 (1) ◽  
pp. 41-49 ◽  
Author(s):  
S. Homuth ◽  
A. E. Götz ◽  
I. Sass
Keyword(s):  
Thermal Conductivity ◽  
Reservoir Characterization ◽  
Upper Jurassic ◽  
Dominant Factor ◽  
Physical Parameters ◽  
Minor Effect ◽  
Molasse Basin ◽  
Reservoir Property ◽  
Triaxial Cell ◽  
Reservoir Conditions

<p><strong>Abstract.</strong> The Upper Jurassic carbonates of the southern German Molasse Basin are the target of numerous geothermal combined heat and power production projects since the year 2000. A production-orientated reservoir characterization is therefore of high economic interest. Outcrop analogue studies enable reservoir property prediction by determination and correlation of lithofacies-related thermo- and petrophysical parameters. A thermofacies classification of the carbonate formations serves to identify heterogeneities and production zones. The hydraulic conductivity is mainly controlled by tectonic structures and karstification, whilst the type and grade of karstification is facies related. The rock permeability has only a minor effect on the reservoir's sustainability. Physical parameters determined on oven-dried samples have to be corrected, applying reservoir transfer models to water-saturated reservoir conditions. To validate these calculated parameters, a Thermo-Triaxial-Cell simulating the temperature and pressure conditions of the reservoir is used and calorimetric and thermal conductivity measurements under elevated temperature conditions are performed. Additionally, core and cutting material from a 1600 m deep research drilling and a 4850 m (total vertical depth, measured depth: 6020 m) deep well is used to validate the reservoir property predictions. Under reservoir conditions a decrease in permeability of 2–3 magnitudes is observed due to the thermal expansion of the rock matrix. For tight carbonates the matrix permeability is temperature-controlled; the thermophysical matrix parameters are density-controlled. Density increases typically with depth and especially with higher dolomite content. Therefore, thermal conductivity increases; however the dominant factor temperature also decreases the thermal conductivity. Specific heat capacity typically increases with increasing depth and temperature. The lithofacies-related characterization and prediction of reservoir properties based on outcrop and drilling data demonstrates that this approach is a powerful tool for exploration and operation of geothermal reservoirs.</p>

scholarly journals S-wave experiments for the exploration of a deep geothermal carbonate reservoir in the German Molasse Basin

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Britta Wawerzinek ◽  
Hermann Buness ◽  
Hartwig von Hartmann ◽  
David C. Tanner
Keyword(s):  
Upper Jurassic ◽  
Carbonate Reservoir ◽  
P Wave ◽  
Seismic Survey ◽  
Seismic Exploration ◽  
Molasse Basin ◽  
S Wave ◽  
Induced Earthquakes ◽  
Conversion Point ◽  
Facies Classification

AbstractThere are many successful geothermal projects that exploit the Upper Jurassic aquifer at 2–3 km depth in the German Molasse Basin. However, up to now, only P-wave seismic exploration has been carried out. In an experiment in the Greater Munich area, we recorded S-waves that were generated by the conventional P-wave seismic survey, using 3C receivers. From this, we built a 3D volume of P- to S-converted (PS) waves using the asymptotic conversion point approach. By combining the P-volume and the resulting PS-seismic volume, we were able to derive the spatial distribution of the vp/vs ratio of both the Molasse overburden and the Upper Jurassic reservoir. We found that the vp/vs ratios for the Molasse units range from 2.0 to 2.3 with a median of 2.15, which is much higher than previously assumed. This raises the depth of hypocenters of induced earthquakes in surrounding geothermal wells. The vp/vs ratios found in the Upper Jurassic vary laterally between 1.5 and 2.2. Since no boreholes are available for verification, we test our results against an independently derived facies classification of the conventional 3D seismic volume and found it correlates well. Furthermore, we see that low vp/vs ratios correlate with high vp and vs velocities. We interpret the latter as dolomitized rocks, which are connected with enhanced permeability in the reservoir. We conclude that 3C registration of conventional P-wave surveys is worthwhile.

Magnetic Erasures Due to Impact Induced Interfacial Heating and Magnetostriction

1999 ◽  
Vol 122 (1) ◽  
pp. 264-268 ◽  
Author(s):  
M. Suk ◽  
P. Dennig ◽  
D. Gillis
Keyword(s):  
Thermal Conductivity ◽  
High Speed ◽  
Magnetic Layer ◽  
Substrate Material ◽  
Contact Stresses ◽  
Dominant Factor ◽  
Disk Drives ◽  
Mechanical Contact ◽  
Low Thermal Conductivity ◽  
Interfacial Temperature

High-velocity intermittent contacts between a slider and a disk may lead to data erasure due to interfacial heating and high-speed mechanical contact stresses. These potential modes of erasure are investigated by artificially introducing high contact stresses that are not likely to be observed in disk drives. Nevertheless, the mechanisms of erasure are delineated in this study with little ambiguity by comparing the results from three different substrate materials, namely Al-Mg, glass, and Si. We show that written flux patterns can be erased if either the substrate material has low thermal conductivity or if the magnetic layer is damaged. We conclude that if the disk is not plastically damaged by high-speed contacts, then the magnetostriction effect or stress-induced erasure is insignificant. In this case, the dominant factor in erasure is a rise in the interfacial temperature, which is exacerbated by low thermal conductivity of the substrate. [S0742-4787(00)03401-9]

Thermal aspects of Oldroyd-B nanofluid over accelerated surface with variable thermal conductivity and modified diffusion theories

2021 ◽  
pp. 2150185
Author(s):  
Samaira Aziz ◽  
Iftikhar Ahmad ◽  
Sami Ullah Khan ◽  
Nasir Ali
Keyword(s):  
Thermal Conductivity ◽  
Concentration Profile ◽  
Heated Surface ◽  
Variable Thermal Conductivity ◽  
Physical Parameters ◽  
Rheological Analysis ◽  
Heating Systems ◽  
Boundary Layer Equations ◽  
Relaxation Parameters ◽  
Thermal Sciences

The growing interest in emerging nanotechnologies has led the scientists towards to investigate the interaction of nanoparticles with fluids. Current continuation endeavors the rheological analysis for the Oldroyd-B nanomaterial across periodically accelerated and heated surface. The interesting features of thermophoresis and Brownian motions are presented by following famous Buongiorno nanofluid model. Further, Cattaneo–Christov heat and mass flux expressions are exploited to determine the characteristics of thermal and mass diffusions. As a novelty, the variable thermal conductivity and heat absorption/generation consequences are also utilizing the energy equation. The flow model has been developed by using concerning boundary layer equations which are converted into dimensionless forms by using appropriate variables. The analytical solution of such transmuted equations is computed by using homotopy analytic method. Various physical parameters of interest are scrutinized through various graphs. The observations from analysis convey a declining change in nanofluid concentration and temperature with variation of thermal and solutal relaxation parameters, respectively. Moreover, thermophoresis parameter causes an enhancement of concentration profile while a retarded concentration profile results with increment of Schmidt number. The obtained theoretical results reflect significant applications in cooling and heating systems, thermal sciences, manufacturing processes, extrusion systems, enhancement of transport of energy and heat resources.

Effect of Variable Thermal Conductivity Calibration Functions on Fin Temperature Distribution

2019 ◽  
Vol 393 ◽  
pp. 47-58 ◽  
Author(s):  
Partner Luyanda Ndlovu ◽  
Raseelo Joel Moitsheki
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Variational Iteration Method ◽  
Variable Thermal Conductivity ◽  
Solution Technique ◽  
Physical Parameters ◽  
Calibration Function ◽  
Shooting Technique ◽  
Extended Surfaces ◽  
Fourth Order Method

In this article, we introduce a new thermal conductivity calibration function in modeling heat transfer through extended surfaces. The variable thermal conductivity functions are studied on a stand alone basis and further compared to one another. The calculations are carried out using the Variational Iteration Method (VIM) which is an analytical solution technique. The series solutions are bench-marked against the numerical results obtained by applying the Runge-Kutta fourth order method coupled with shooting technique. The effects of some physical parameters such as the thermogeometric fin parameter and thermal conductivity gradient, on temperature distribution are illustrated and explained.

Analysis of Structural Vibrations of Vertical Axis Wind Turbine Blades via Hamilton’s Principle — Part 2: Exact and Approximate Solutions

2020 ◽  
Vol 20 (09) ◽  
pp. 2050099
Author(s):  
Jianyou Huang ◽  
Chia-Ou Chang ◽  
Chien-Cheng Chang
Keyword(s):  
Natural Frequencies ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Angular Speed ◽  
Chord Length ◽  
Dominant Factor ◽  
Physical Parameters ◽  
Vertical Axis Wind Turbine ◽  
Lateral Bending ◽  
Blade Length

In this part 2, we provide a detailed solution to the beam equations derived in Part 1 for a VAWT blade. The main results have been outlined in the abstract of Part 1 which includes the effects of various geometrical and physical parameters such as blade length [Formula: see text], chord length [Formula: see text], radius [Formula: see text] and angular speed [Formula: see text] as well as material damping [Formula: see text]. It is shown that among the four dimensions of deformation lateral bending is the dominant factor in determining the natural frequencies of the blade. In case the blade is rotating with a constant angular speed, the dispersion relation of the 1 degree-of-freedom (DOF) motion for lateral bending can be exactly derived that an implicit function of the natural, i.e. resonant frequencies has to be solved by a root-finding method. The mode shape function is then explicitly obtained. In particular, the natural frequencies of the 1-DOF motion for the rotating blade are shown to be conveniently approximated by simple analytical formulas in terms of those for the stationary blade and the angular speed of rotation. The dependence of the natural frequencies on the chord length can also be approximated analytically by a ratio formula for given blade length to chord ratio. In addition, resonance maps of natural frequency plotted versus various parameters are provided to fully exploit the usefulness of the main results. Through a series of analysis of 2-DOF systems, we show the respective importance of the centrifugal force, coupling deformation and the Coriolis force in modifying the natural frequencies of the 1-DOF model rather than simply ignoring any of these effects.

scholarly journals Temporal evolution of fault systems in the Upper Jurassic of the Central German Molasse Basin: case study Unterhaching

2017 ◽  
Vol 107 (2) ◽  
pp. 635-653 ◽  
Author(s):  
Ingmar Budach ◽  
Inga Moeck ◽  
Ewald Lüschen ◽  
Markus Wolfgramm
Keyword(s):  
Temporal Evolution ◽  
Upper Jurassic ◽  
Molasse Basin ◽  
Fault Systems

Lattice Boltzmann Simulations for Thermal Conductivity Estimation in Heterogeneous Materials

2009 ◽  
Vol 283-286 ◽  
pp. 364-369 ◽  
Author(s):  
M.R. Arab ◽  
Bernard Pateyron ◽  
Mohammed El Ganaoui ◽  
Nicolas Calvé
Keyword(s):  
Thermal Conductivity ◽  
Porous Medium ◽  
Lattice Boltzmann ◽  
Numerical Study ◽  
Theoretical Models ◽  
Short Description ◽  
Physical Parameters ◽  
Two Dimensional ◽  
Lattice Boltzmann Simulations ◽  
Boltzmann Method

For simulating flows in a porous medium, a numerical tool based on the Lattice Boltzmann Method (LBM) is developed with regards to the classical D2Q9 model. A short description of this model is presented. This technique, applied to two-dimensional configurations, indicates its ability to simulate phenomena of heat and mass transfer. The numerical study is extended to estimate physical parameters that characterize porous materials, like the so-called Effective Thermal Conductivity (ETC) which is of our interest in this paper. Obtained results are compared with those which could be found analytically and by theoretical models. Finally, a porous medium is considered to find its ETC.

Study on Influence of Thermal Conductivity of Building Material on People's Physiology and Psychology

2013 ◽  
Vol 779-780 ◽  
pp. 278-281
Author(s):  
Ameng Zhao ◽  
Guang Cheng Cui ◽  
Yong Zhuo Ding ◽  
Ting Yu ◽  
Jing Chao Xu
Keyword(s):  
Thermal Conductivity ◽  
Building Material ◽  
Building Materials ◽  
Environmental Science ◽  
Subjective Rating ◽  
Physical Parameters ◽  
Theta Waves ◽  
Coefficient Of Thermal Conductivity ◽  
Physiological Indexes ◽  
Electrocardiogram Ecg

This study was conducted to discover the relations between thermal property of building materials and people's physiology and psychology. Heart rate variability of electrocardiogram ( ECG ) and alpha, beta, theta waves of electroencephalogram ( EEG) were examined in ten adult healthy volunteers. And also a combined analysis on inner correlations among physical parameters of material, human physiological indexes and subjective rating was proceeded. Physiological experiment research was carried out in environmental science laboratory. Environmental stimuli derived mainly from the building material to be tested. The results suggest that the density and coefficient of thermal conductivity are decisive effect factors on the physiological changing degree of human.

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