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As same as other countries in the world, China is also facing the problem of a severe shortage of energy. Specifically, the demand for natural gas is rising explosively after the energy consumption structure has changed from oil to gas. Due to various reasons and motivations, shale has been considered having great reserves and believed in alleviating the energy crisis. Nevertheless, the massive investment in developing shale has a disappointing interest with low-yielding production. Scholars have done many researches and experiments for investigating the causes and increasing the productivity of shale formation, in field and in laboratory respectively. Based on the statistics, more details, and further discussion, in this dissertation a probable method for more effectively producing was demonstrated. Although the hydro-fracturing technology has been conducted in field frequently, sometimes the decrease of permeability has been observed after the treatment. To figure out this phenomenon, the investigation started from the basic characterization of matrix. Believed in the most component in shale, quartz consisted of silica which could dissolve in fluid. Been assigned as variables, temperature, pH, and salinity have been implemented for explanation of dissolution. Temperature played a great role in the process. Combined with confining pressure, the reconsolidation happened inside samples. Through more experiments the mechanism of reconsolidation has been discovered that both confining pressure and temperature are necessary for gelling in fracture. Perspective on the whole formation, well logs were a super supplement to laboratory experiments. It serviced not only a further confirmation, but also pointed out the relationship between desorption capacity and different components. Samples from upper and lower formations have been used for going further. The exchange which exists between N2 and CH4 could be a great idea to exploit gas from reservoir. Feldspar supported space for adsorbed gas, and it was also easy to release. In contrast, the organic matter in which a network of pores developed has ability to trap the gas deeply because of the specific surface area. Quartz had positive effect on production because of containing the organic matter, while the influence of clay minerals on adsorption and desorption could be neglected. Based on the analysis of reconsolidation and desorption, an idea has been conceived using foam as fracturing fluid for increasing gas production. Compared to the pure fluid, foam has less water, which could prevent the reconsolidation. Nitrogen could be the gas to foam. The exchange between N2 and CH4 will increase the production of gas. In order to serve the condition that increases the time of exchange and makes negative effect on reconsolidation simultaneously, the foaming test with ABS and K12 has been evaluated first. For better stability of foam more experiment have been done. Three formulas were recommended which could keep the balance between the increasing viscosity and decreasing volume. The work interpreted in this thesis has enhanced our understanding of microscopic properties of shale and was expected to make contribution to further research of fracturing and production design.

Microbial Enhanced Oil Recovery (MEOR) represents a promising economic and sustainable EOR approache but is still scarcely employed due to its image as a “black-box” technology. Within the framework of this dissertation, opportunities for in situ MEOR in a low-temperature (37 °C) and high-salinity (180 g*L-1) oilfield by stimulating the growth of anaerobic fermentative bacteria of the order Halanaerobiales was assessed using dynamic sandpacks operated anaerobically under 5 bar with different materials including crushed reservoir rock and resulting in reservoir-representative permeabilities of 10,000 – 800 mD. Wettability alteration, mineral dissolution and potentially selective plugging were the main contributors for oil mobilization, but were not fully accounted for in water-wet sandpacks with quartz sand. However, incremental recovery in sandpacks with reservoir rock was 23.2 ± 6.4 %, with respect to the Original Oil In Place (OOIP). Sucrose consumption rates in sandpacks with oil-wet crushed reservoir rock with a cumulative content of 1.2 % carbonates and sulfides was six-fold higher compared to inert quartz sand, i.e. 3.7 mM*d-1. The dissolution of surface-coating minerals was confirmed by both XPS measurements and a decrease in specific surface area and is assumed to have induced the observed wettability change towards more water-wet conditions which was concurrent with significant incremental oil recovery. Besides promoting oil recovery, microorganisms can also have detrimental effects in oil reservoirs, most notably by the activity of Sulfate Reducing Microorganisms (SRM). Molybdate was tested as a SRM-specific souring control agent not interfering with the chosen MEOR approach. 0.5 mM molybdate resulted in the sustained and complete inhibition of SRM over twenty days in batch experiments, but significant adsorption of ≥ 34 µmolMolybdate*g-1Rock to reservoir rock was observed, mainly controlled by accessory amounts of pyrite and iron (hydr)oxides. In summary, this thesis combined reservoir engineering, microbiological and geological aspects for an interdisciplinary approach on MEOR. It was shown for the first time that MEOR is applicable to reservoirs with a salinity of up to 180 g*L-1, thus extending previous recommendations for a maximum salinity of 10 %. In addition, these results indicate that in situ, fermentation based MEOR has potential for supporting the transition phase between the age of fossil fuels to alternative energy sources as an economic and sustainable tertiary recovering technique for enhancing oil recovery from mature fields., Microbial Enhanced Oil Recovery (MEOR) kann maßgeblich zu einer effizienteren Ausbeutung von sich bereits lange in Produktion befindlichen Erdöllagerstätten beitragen, findet bisher allerdings auf Grund der vorherrschenden Reputation als „Black Box“-Technologie nur selten Anwendung. Im Rahmen dieser Dissertation wurde das Potential für in situ MEOR in einer Onshore-Lagerstätte mit einer Salinität von 180 g*L-1 und einer Temperatur von 37 °C mittels fermentativen Wachstum anaerober, halophiler Bakterien der Ordnung Halanaerobiales, das durch die Injektion von Saccharose in situ angeregt wurde, erkundet. Hierzu wurden sogenannte Sandpacks mit verschiedenen Materialien und einer lagerstättenspezifischen Permeabilität von 10,000 – 800 mD angefertigt, die unter 5 bar mit verschiedenen, dem Testfeld entnommenen Fluiden geflutet wurden. Die Änderung der Benetzbarkeit, Mineralauflösung und sowie potentiell selektives Plugging wurden als Hauptmechanismen für MEOR identifiziert, allerdings konnten nicht all diese Effekte in Sandpacks mit reinem Quarzsand beobachtet werden, sodass die inkrementelle Mehrentölung lediglich ungefähr ein Drittel im Vergleich zu Sandpacks mit Lagerstättengestein, die eine Mehrentölung von 23,2 ± 6,4 % aufwiesen, betrug. Die Saccharose-Abbaurate in Sandpacks mit Lagerstättengestein mit einem kumulativen Gehalt von 1.2 % Karbonaten und Sulfiden betrug im Vergleich zu Sandpacks mit inertem Quarzsand etwa das sechsfache, 3,7 mM*d-1. Zeitgleich wurden eine Abnahme der spezifischen Oberfläche sowie eine Auflösung von oberflächlichen Eisenmineralen mittels XPS registriert. Die beobachteten Änderungen der relativen Permeabilitäten deuten zudem darauf hin, dass dieser hauptsächlich oberflächliche Prozess die Benetzbarkeitsänderung in Richtung einer hydrophileren Oberfläche des porösen Mediums ausgelöst hat. Mikroorganismen können eine Erdöllagerstätte auch nachteilig beeinflussen, maßgeblich durch die Aktivität von Sulfat reduzierenden Mikroorganismen (SRM). Molybdat wurde hier als ein SRM-spezifisches und den MEOR-Ansatz nicht nachteilig beeinflussendes Inhibierungsmittel getestet. Die Zugabe von 0.5 mM Molybdat führte in Batchversuchen zu einer Hemmung der Aktivität von SRM über den gesamten Versuchszeitraum von 20 Tagen, allerdings wurde mit einer geschätzten Langmuir-Sättigung von ≥ 34 µmolMoO4*g-1Gestein eine beträchtliche Adsorption am Lagerstättengestein festgestellt. Die vorliegende Dissertation vereint unter Berücksichtigung geologischer Aspekte sowohl Aspekte des Lagerstätteningenieurwesens als auch der Mikrobiologie. Es wurde erstmals gezeigt, dass MEOR auch in Ölfeldern mit einer Salinität von 180 g*L-1 Anwendung finden kann und die Ergebnisse lassen darauf schließen, dass in situ MEOR eine vielversprechende und gleichzeitig ökologische Methode darstellt, um während der bevorstehenden Übergangsphase zwischen dem Ölzeitalter hin zu einer wie auch immer gearteten alternativen Energieversorgung einen bedeutsamen Beitrag zu leisten.

This study focuses on the environmental impact assessment of trace elements concentrations in spent shale, which is the main residual besides gas and steam from the utilization of oil shale. The study area El-Lajjun covers 28 km2, located in the centre of Jordan approximately 110 km south of Amman. It belongs mainly to the Wadi Mujib catchment and is considered to be one of the most important catchments in Jordan. The Wadi El-Lajjun catchment area (370 km2) consists of two main aquifer systems: The intermediate aquifer (Amman Wadi As Sir Aquifer or B2/A7) and the deep sandstone aquifer (Kurnub/Ram Group Aquifer). The B2/A7 aquifer (Upper Cretaceous) is considered as the main source of fresh water in Jordan. El-Lajjun oil shale was deposited in a sedimentary basin and comprises massive beds of brown-black, kerogen-rich, bituminous chalky marl. The oil shale was deposited in shallow marine environment. It is by definition a sedimentary rock containing organic material in the rock matrix. The shale oil extraction is an industrial process to decompose oil shale and to convert the kerogen into shale oil by hydrogenation, pyrolysis or by a thermal dissolution. Several classifications of extraction technologies are known; the classification with respect to the location where the extraction takes place distinguishes between off-site, on-site, and in situ. The oil shale utilization may have serious repercussions on the surrounding environment if these issues are not investigated and evaluated carefully. Ten representative oil shale rock samples with a total weight about 20 kg were collected from different localities of oil shale exposures in the study area. A standardized laboratory Fischer Assay test was performed with the samples to determine oil shale characteristics and to obtain spent shale, which was used in this study for further investigations. Sequential extraction was used to evaluate the changes in the mobility and distribution of the trace elements: Ti, V Cr, Co, Zn, As Zr, Cd, Pb and U. Column leaching experiments were performed to simulate the leaching behavior of the above elements from oil shale and spent shale to evaluate the possible influence on the groundwater in the study area. The concentrations in the leachate were below the maximum contaminant levels of the Environmental Protection Agency (EPA) for drinking water and the Jordanian standards for drinking water. An immobilization method by using Kaolin was applied to reduce the mobilization and bioavailability of the trace elements fraction that are contained in the spent shale. Immobilization was evaluated as a function of liquid-solid ratio (solid-liquid partitioning) and as a function of pH. A comparison between the results obtained from column leaching experiments and the results that were obtained from immobilization for the oil shale and spent shale samples indicated that the immobilization reduced the mobility of the trace element except for Ti, V, and Cr. However, even the concentrations of these elements were lower than the maximum acceptable limits of the Jordanian Standard Specifications for waste water. The catchment of the study area (Wadi El-Lajjun catchment) is ungauged. Therefore, the soil conservation service (SCS) runoff curve number method was used for predicting direct runoff from rainfall. The results obtained showed that the infiltration of water is very small (approximately 0.6 cm/year) and rarely can´t reach the groundwater through the oil shale beds. Thus, a contamination of groundwater is unlikely under normal conditions. DRASTIC was used to assess groundwater vulnerability for the B2/A7 aquifer with respect to pollution by oil shale utilization. The aquifer vulnerability map shows that the area is divided into three zones: low (risk index 10-100; intermediate (risk index 101–140) and high groundwater vulnerability (risk index 141-200). The high risk areas are small and mainly located in the northeastern corner of the El-Lajjun graben, where the hydraulic conductivity is relatively high and rocks are highly fractured and faulted. The water table of the deep sandstone aquifer (Kurnub/Ram group) in the El-Lajjun area is relatively deep. At least two geological formations above the Kurnub aquifer are aquitards and protect the deep aquifer. However, the area is highly fractured and thus there is a certain possibility for contact with surface pollutants. Finally, further research with respect to trace elements including REE elements and isotopes in the intermediate and deep sandstone aquifers are highly recommended. Isotopic signatures will be very helpful to investigate to which extend hydraulic connections between the aquifers exist. Further and in particular mineralogical studies on the spent shale and the possibilities for industrial utilization are recommended because huge quantities of spent shale are expected. Because most oil shale extraction technologies especially the power generation require considerable amounts of water detailed studies on water supply for the oil shale treatment have to be performed.