Den technologischen Hintergrund für diese Arbeit liefert die bei der Erschließung tiefer Lagerstätten (Erdgas, Erdöl, Erdwärme) eingesetzte Stimulationstechnik des Hydraulic Fracturing. Bei dieser Technik werden mittels hydraulischem Druck Risse im Lagerstättengestein erzeugt, die durch Einspülen von Feststoffkörnern (Proppants) offengehalten werden sollen. Der inhaltliche Schwerpunkt liegt auf der theoretischen und experimentellen Untersuchung der Einbettung von Proppants in das Lagerstättengestein unter besonderer Berücksichtigung des Einflusses auf die hydraulische Leitfähigkeit eines durch Proppants gestützten Risses. Thematisch teilt sich die Arbeit in die beiden Schwerpunkte: (1) Berechnung der Proppant-Einbettung auf der Grundlage kontaktmechanischer Ansätze und (2) experimentelle Untersuchungen an realen Proppant-Schüttungen. Zur mathematischen Formulierung der Proppant-Einbettung wurde die in der Werkstofftechnik entwickelte Theorie des mechanischen Verhaltens rauer Oberflächen unter Lasteintrag (Kontaktmechanik) mit der ebenfalls aus der Werkstofftechnik bekannten Messung und Interpretation der Oberflächenhärte nach Meyer gekoppelt. Diese neuartige Formulierung ermöglicht es, die Einbettung von Proppants in Abhängigkeit der Materialeigenschaften der Formation, des Spannungszustandes, der Korngrößenverteilung und der Proppants-Konzentration zu berechnen. Zur Prognose des Erfolges einer Stimulation wurde ein 2D-numerischer Algorithmus (MATLAB®) entwickelt, der den Gesamtprozess der Einbettung, der Durchlässigkeitsentwicklung und deren Folgen für die Produktivität der Sonden widerspiegelt. Zur Verifizierung des Berechnungsalgorithmus wurde die Einbettung realer Proppant-Schüttungen in Lagerstättengesteinen (Tonschiefer, Shale) untersucht. Hierfür wurde in einer dafür konzipierten Flutzelle ein durch Proppants gestützter Riss nachgebildet, belastet und durchströmt. Ziel der Versuche war dabei zu messen, welchen Einfluss ein Spannungsanstieg auf die Einbettung und damit auf die hydraulische Leitfähigkeit hat. Diese Versuche wurden an zwei verschiedenen Shale-Gesteinen mit zwei verschiedenen Proppant-Konzentrationen durchgeführt. Zusätzlich zu den hydraulischen Experimenten wurden mechanische Untersuchungen (Härtemessungen) ausgeführt und nach der Meyer-Analyse der Werkstofftechnik interpretiert. Ein besonderer Vorteil dieser Auswertungsmethode liegt in ihrer durch Dimensionsanalyse erzielten Übertragbarkeit der Ergebnisse von Werkstoffen auf Gesteine. Der Vergleich von gemessenen und berechneten Einbettungen und hydraulischen Leitfähigkeiten ergab eine zufriedenstellende Übereinstimmung und erlaubt es festzustellen, dass mit der neuen Formulierung die planerische Voraussage von Frac-Stimulation möglich ist, wobei alleine die relativ einfachen laborativen Messverfahren zur Härtemessung (Gestein) und zur Korngrößenanalyse (Proppant) erforderlich sind.

The work of an engineer is closely intertwined with safety. An engineer’s perception of the “safety” task is traditionally inherent in his or her design. However, in the technical world most machines and systems designed by engineers contain a human element, which engineers have to consider in their work. In the oil and gas upstream industry – especially drilling, production and workover operations – petroleum engineers (including drilling and production engineers) are responsible not only for design but also for operational and organizational aspects. The human factor becomes more important in complex offshore operations. Incorporating safety into a sys-tem design requires identifying, analyzing and evaluating risks and ensuring that any not accounted for are taken into consideration. This process requires communication among everyone involved in the process. Analysis of accidents in the oil and gas industry shows that often a lack of that communication led to incident triggering events. In this thesis, the author proposes a novel communication model that improves this exchange of information and supposedly makes the process of risk assessment more effective. In addition, the new model also incorporates factors such as emotions, feelings, needs and imagination into the risk assessment process. This broadens the information base for the risk identification and analysis and creates an atmosphere of psychological ownership for the stakeholders in the process, which leads to a perceived safety climate in the organization where the new model is applied. The innovative communication or consultation model, as it is also referred to in risk assessments, is based on a structured process used in conflict resolution called mediation. Mediation is an alternative conflict resolution process that is centered on mutual under-standing and listening to each other’s needs. The process is composed of elements that characterize it. These elements of mediation are used to assess other communication processes and to develop new communication models. The application of the elements of mediation and the safety-mediation consultation into the risk assessment process enables this process to be enhanced with human factors such as emotions, feelings, intuition and imagination. The inclusion of all stakeholders creates psychological ownership, improves communication, enables organizational learning and expands the knowledge base for risk analysis. The applicability of the safety-mediation consultation process for a human factor-based risk assessment is presented and tested using illustrative examples and field cases from the international oil and gas industry. Possible concerns and limitations are also discussed. This thesis shows that mediation and elements of the mediation process can be applied to improve communication in the international oil and gas industry. This is facilitated by educated safety mediators, who help the petroleum engineer and operational crew on a drilling rig to achieve a better understanding by ensuring that they hear and fully register each other’s needs.

The aim of this research work is to deepen the understanding of joint shear behavior under different boundary conditions. For this purpose, joint closure tests under quasi-static and dynamic conditions, direct shear and cyclic shear tests under CNL and DNL boundary conditions of plane joints are performed using GS-1000 big shear box device. The dissertation also presents the procedure to simulate the shear box device and simulating the behavior of plane joints at the micro-scale using FLAC3D. Special attention has been given to understand the influencing factors of the normal stress level, direct shear rate, horizontal cyclic shear frequency, normal impact frequency, horizontal cyclic shear displacement amplitude and vertical impact force amplitude. Lab test and numerical simulation results show that the quasi-static joint stiffness increases with increasing normal force. Dynamic joint stiffness decreases with increasing superimposed normal force amplitudes. Normal impact frequencies have little influence on the joint stiffness. Rotations and stress changes at the plane joint during shearing are proven. Rotations and development of stress gradients can be decreased significantly by increasing the size of the bottom specimen and applying a shear velocity at the upper shear box and normal loading piston. Furthermore, peak shear force increases with increasing normal force. Friction angle of cyclic shear tests is smaller than that of direct shear tests. Moreover, significant time shifts between normal and shear force (shear force delay), normal force and friction coefficient (friction coefficient delay) during direct shear tests under DNL boundary conditions are observed and the reference quantity ‘shear-velocity-normal-impact-frequency’ (SV-NIF) to describe the behavior under DNL boundary conditions is defined. Peak shear force and minimum friction coefficient increase with increasing SV-NIF. Relative time shift between normal force and shear force decreases with increase of SV-NIF. The mechanical behavior of the GS-1000 big shear box device is simulated and the loss of normal force caused by the tilting of the loading plate is quantified. Finally, the novel direct and cyclic shear strength criterions under DNL conditions are put forward. The shear strength criterions are in close agreement with the measured values, which indicates that the novel shear strength criterions are able to predict the shear strength under DNL conditions.

Cotttaer sandstone is a quite popular material used for sculptures and monuments for almost 1,000 years. Such sculptures and monuments will be damaged after several years. The reasons for that could be different: mechanical damage due to carving by sculptors, expansion stresses due to salt crystallization or temperature change. Damages also happen sometimes after inappropriate consolidation. Cottaer sandstone before and after consolidation was investigated by lab testing and numerical simulations in this thesis. The aim is to develop a simulation strategy which can simulate the thermomechanical coupled damage behavior at grain size level. The main research works of this thesis are as follows: *Uniaxial compression tests, Brazilian tension tests and size effect tests were carried out to investigate the mechanical parameters of original Cottaer sandstone. *Ultrasonic wave velocity measurement and special biaxial flexural tests were carried out to determine how deep the consolidation material penetrates and how much strength of sandstones is increased by using two different injection materials. *A Voronoi-based numerical simulation strategy was developed which considers grain size, grain shape and pore size. Mineral components, intra- and inter-granular contacts and intra- and inter-granular fracturing were considered as well. *Uniaxial compression tests and Brazilian tension tests of unconsolidated sandstone were simulated. This simulation strategy can capture inter- and intra-granular fracturing. *Prediction of thermo-mechanical coupled behavior of consolidated and unconsolidated sandstone samples was performed. The simulation results show that thermal properties of grains and filled pores have influence on temperature distribution and fracture development in the sandstone. Also, thermal induced displacements are strongly influenced by boundary condition.

Even in times of renewable energy revolution fossil fuels will play a major role in energy supply, transportation, and chemical industry. Therefore, increasing demand for crude oil will still have to be met in the next decades by developing new oil re-serves. To cope with this challenge, companies and researchers are constantly seeking for new methods to increase the recovery factor of oil fields. For that reason, many enhanced oil recovery (EOR) methods have been developed and applied in the field. EOR methods alter the physico-chemical conditions inside the reservoir. One possibility to achieve this is to inject an aqueous solution containing special chemicals into the oil-bearing zone. Polymers, for example, increase the viscosity of the injected water and hence improve the displacement of the oil to the production well. The injection of surfactant solutions results in reduced capillary forces, which retain the oil in the pores of the reservoir. Some surfactants form viscoelastic solutions under certain conditions. The possibil-ity to apply those solutions for enhanced oil recovery has been investigated by some authors in the last years in low salinity brines. Reservoir brines, however, often contain high salt concentrations, which have detrimental effects on the properties of many chemical solutions applied for EOR operations. The Triphenoxymethane derivatives, which were the subject of study in this thesis, form viscoelastic solutions even in highly saline brines. The aim of this thesis was to investigate the efficiency and the mode-of-action of this new class of chemical EOR molecules with respect to oil mobilization in porous media.

The anisotropic behavior of a rock mass with persistent and planar joint sets is mainly governed by the geometrical and mechanical characteristics of the joints. The aim of the study is to develop a continuum-based approach for simulation of multi jointed geomaterials. There are two available numerical techniques for the strain-stress analysis of rock masses: continuum-based methods and discontinuum based methods. Joints are simulated explicitly in discontinuous methodology. This technique provides a more accurate description for the behavior of a rock mass. However, in some projects, the explicit definition becomes impractical, especially with increasing number of joints. Besides, the calculation efficiency will be significant reduced as the number of joints increases within the model. Considering the above mentioned shortcomings of the discontinuous method, the continuum-based approach is widely used in rock mechanics. Within the continuum methods, the discontinuities are regarded as smeared cracks in an implicit manner and all the joint parameters are incorporated into the equivalent constitutive equations. A new equivalent continuum model, called multi-joint model, is developed for jointed rock masses which may contain up to three arbitrary persistent joint sets. The Mohr-Coulomb yield criterion is used to check failure of the intact rock and the joints. The proposed model has solved the issue of multiple plasticity surfaces involved in this approach combined with multiple failure mechanisms. The multi-joint model is implemented into FLAC and is verified against the distinct element method (UDEC), analytical solutions, and experimental data. Uniaxial compression tests with artificial rock-like material (gypsum) are carried out in the laboratory in order to verify the developed constitutive model and to investigate the behavior of jointed specimen. Samples with two crossing joints covering more than 20 angle configurations and two different property sets were prepared and tested. Simulation results are in good agreement with experimental observations. The developed model is applied to two potential practical applications: the stability analysis of a slope and a tunnel under different stress conditions. Finally, the main achievements of the whole PhD study are summarized and future research work is proposed.

High-level radioactive waste (HLW) poses threat to the biosphere. Geological disposal is accepted as a safe way for HLW disposal. Waste canisters made of Sintered Silicon Carbide (SSiC) are proposed and geomechanical safety aspects relating to such SSiC canisters are investigated. First part of the thesis reviews the state-of-the-art and demands for HLW disposal. The reason for considering Silicon Carbide (SiC) as canister material is explained. Especially in terms of corrosion and lifetime, ceramics and especially SiC is superior to metals or concrete. The only concern is its brittle behavior. The second part of the thesis presents results on static and dynamic mechanical properties of SiC in general and in particular for SSiC based on literature review and own lab tests. Although strength values for SiC and especially SSiC are very high, the extreme brittle behavior has to be considered in case of impact or point-like loading. The third and most extensive part of the thesis part contains numerical simulations, which consider most critical potential loading situations during transport and installation of the canisters underground. Both, pure elastic continuum and DEM based models are used considering the following loading situations (critical scenarios): Freefall of canister during transport or installation (FF), Impact by falling rock block at disposal site (RF), Point loading due to accidental insertion of small stone below the canister (PL), Anisotropic earth pressure loading after disposal (EP). Coating to protect the canisters against damage is investigated and preliminary parameters in terms of stiffness and thickness are recommended.

The present-day challenge of oil industry is gradual decrease of conventional light crude reserves and increased consumption of hard-to-recover heavy crude. The goal of thesis is to establish change regularities of structural-mechanical properties and thermody-namic activation parameters for viscous flow in oil dispersed systems (ODS) of various composition (paraffin and naph-thene and aromatic bases) from Timan-Pechora petroleum region (Russia) in a broad range of temperatures and shear rates and under the exposure of external fields, and also to experimentally determine phase diagrams of binary hydrocarbon systems (nonadecane – decaline and nonadecane – naphthalene) modeling ODS mixture of completely opposite nature. Study results can be used for predicting and preventing structure formation during production, transport and storage of ODS's with various content of solid paraffins, resins and asphaltenes.:INTRODUCTION CHAPTER 1. ANALYSIS OF THE MODERN CONDITION AND METHODS OF RESEARCH OF HEAVY OILS 1.1 The current state of hydrocarbon reserves 1.2 Oil classification 1.3 Oil chemical composition 1.4 Influence of components of oil dispersed systems on their low-temperature properties 1.5 Structuring in oil dispersed systems 1.6 Rheological models of oil dispersed systems 1.7 Evaluation of the thermodynamic characteristics of the activation of the viscous flow of oil dispersed systems 1.8 Chemical composition and structural-mechanical properties of the oils from Timan-Pechora province 1.9 Modern methods of influencing the structure and properties of oil dispersed systems CONCLUSIONS TO CHAPTER 1 CHAPTER 2. OBJECTS AND METHODS OF RESEARCH 2.1 Objects of research 2.1.1 Physical and chemical properties of oils from Timan-Pechora province 2.1.2 Physical and chemical properties of high-boiling fractions from Timan-Pechora province 2.1.3 Physical and chemical properties of light distillate from heavy oil and individual hydrocarbons (nonadecane, decaline and naphthalene) 2.2 Research methods 2.2.1 Methods of conducting research on the physicochemical properties of oils 2.2.2 Methods of determining the group hydrocarbon composition of oil dispersed systems 2.2.3 Method for determination of low-temperature properties of binary systems 2.2.4 Methods for determining the structural and mechanical properties of oil dispersed systems from Timan-Pechora province 2.2.5 Characteristics of sources of external impact on oil 2.2.6. Methods of processing samples by external influence CONCLUSIONS TO CHAPTER 2 CHAPTER 3. INVESTIGATION OF LOW-TEMPERATURE PROPERTIES OF BINARY AND OIL DISPERSED SYSTEMS 3.1 Justification of the computational models used to describe the phase diagrams of binary systems 3.2 Investigation of low-temperature properties on model binary systems of nonadecane-decaline and nonadecane-naphthalene 3.3 Investigation of the low-temperature properties of a light distillate mixture (NK-330 °C) of heavy naphthenic-aromatic Yarega oil and light paraffin haryaga oil CONCLUSIONS TO CHAPTER 3 CHAPTER 4. INVESTIGATION OF CHANGES IN STRUCTURAL AND MECHANICAL PROPERTIES OF OILS AND THEIR HIGH-BOILING FRACTIONS UNDER EXTERNAL EXPOSURE 4.1 Determination of the type of liquid in oil dispersed systems at different temperatures 4.2 Determination of the dependence of the ultimate shear stress of oil dispersed systems on temperature 4.3 Investigation of the thixotropic properties of the oils from Timan-Pechora province 4.4 Impact of external fields on the rheological properties of heavy oil 4.5 Effects of external fields and diluents on the rheological properties of heavy oil CONCLUSIONS TO CHAPTER 4 CHAPTER 5. RESEARCH OF THERMODYNAMIC CHARACTERISTICS OF THE ACTIVATION OF A VISCOUS FLOW OF OILS AND HIGH-BOILING FRACTIONS UNDER DIFFERENT CONDITIONS (TEMPERATURES AND SHEAR RATE) 5.1 Liquidus temperature and activation energy of viscous flow of oil dispersed systems 5.2 Thermodynamic characteristics of the activation of a viscous flow of oil dispersed systems 5.3 Investigations of the strength of intermolecular interaction in oil dispersed systems as a function of the frequency of molecule jumps 5.4 Change in the activation energy of viscous flow of oil dispersed systems with increasing shear rate 5.5 Changes in thermodynamic characteristics of the activation of a viscous flow of oil dispersed systems with increasing shear rate 5.6 Changes in the strength of intermolecular interaction in oil dispersed systems with increasing shear rate CONCLUSIONS TO CHAPTER 5 CONCLUSION LIST OF ACCEPTED REDUCTIONS BIBLIOGRAPHY ANNEX 1. Act of introduction of development in LLC LUKOIL-Ukhtaneftepererabotka APPENDIX 2. Patent of the Russian Federation 'Method of preparation of heavy oil for refining

Im Projekt wurde das Lagrangeverfahren zur Rückrechnung auf Geruchsquellen als IT-Lösung realisiert. Damit können bei Geruchsbeschwerden in Gemengelagen erstmalig Hauptverursacher ermittelt werden. Das Projekt wird als LfULG-Amtshilfe für Immissionsschutzbehörden eingesetzt. Redaktionsschluss: 31.12.2011, Stand: 30.11.2021

This thesis deals with optimization of sound projectors, based on knowledge on the auditory perception. In sound projection it is desired that the lagging projected sound dominates the localization. One of the most limiting factors here is the leading direct sound, which, however, can only be reduced to a limited extent since the focusing capabilities of sound projectors are physically limited. In order to enable the perception-based optimization, it was therefore essential to gain an understanding of the perceptual role of the direct sound in achieving localization dominance of the projected sound, and which perception-based requirements for sound projection result from this role. A review of existing literature on the perception in scenarios with leading and lagging sound revealed that further insights into lag localization dominance were needed to this end. These insights were gained by conducting several psychoacoustic investigations in an anechoic chamber, reproducing the sounds via individual loudspeakers. Lag localization dominance seemed to be strongly influenced by the temporal characteristics of the playback signal. Afterwards, comprehensive perception-based requirements for sound projection were derived and their consequences for the design of sound projectors were discussed. On this basis, a method for the perception-based optimization was developed with the goal to reduce the influence of the direct sound on localization. This method was named localization masking. Localization masking is based on the additional generation of one or more sounds arriving earlier and from another direction than the direct sound at the position of the listener. An investigation under laboratory conditions, using cascaded lead-lag pairs representing the sounds involved, suggested that localization masking has the potential to achieve that goal. Localization masking enabled the initial lag, representing the projected sound, to dominate the localization up to a 7 dB higher level of the initial lead, representing the direct sound. Finally, localization masking was investigated under realistic conditions. Localization masking was applied to real sound projectors in a real room and proved to work. Localization masking enabled a given projector to be effectively used with a playback signal that requires stronger focusing capabilities. Furthermore, localization masking enabled a projector with less strong focusing capabilities to be effectively used with a given playback signal.