Large-scale dynamic hydrofracturing, healing and fracture network characterization

Permeability of a rock is a dynamic property that varies spatially and temporally. Fractures provide the most efficient channels for fluid flow and thus directly contribute to the permeability of the system. Fractures usually form as a result of a combination of tectonic stresses, gravity (i.e. lithostatic pressure) and fluid pressures. High pressure gradients alone can cause fracturing, the process which is termed as hydrofracturing that can determine caprock (seal) stability or reservoir integrity. Fluids also transport mass and heat, and are responsible for the formation of veins by precipitating minerals within open fractures. Veining (healing) thus directly influences the rock’s permeability. Upon deformation these closed factures (veins) can refracture and the cycle starts again. This fracturing-healing-refacturing cycle is a fundamental part in studying the deformation dynamics and permeability evolution of rock systems. This is generally accompanied by fracture network characterization focusing on network topology that determines network connectivity. Fracture characterization allows to acquire quantitative and qualitative data on fractures and forms an important part of reservoir modeling. This thesis highlights the importance of fracture-healing and veins’ mechanical properties on the deformation dynamics. It shows that permeability varies spatially and temporally, and that healed systems (veined rocks) should not be treated as fractured systems (rocks without veins). Field observations also demonstrate the influence of contrasting mechanical properties, in addition to the complexities of vein microstructures that can form in low-porosity and permeability layered sequences. The thesis also presents graph theory as a characterization method to obtain statistical measures on evolving network connectivity. It also proposes what measures a good reservoir should have to exhibit potentially large permeability and robustness against healing. The results presented in the thesis can have applications for hydrocarbon and geothermal reservoir exploration, mining industry, underground waste disposal, CO2 injection or groundwater modeling.

Cultural citizenship and its implications for citizenship education: Chinese university students’ civic experience in relation to mass media and the university citizenship curriculum

A growing body of research has argued that university citizenship curricula are inefficient in promoting civic participation, while there is a tendency towards a broader citizenship understanding and new forms of civic engagements and citizenship learning in everyday life. The notion of cultural citizenship in this thesis concentrates on media practices’ relation to civic expression and civic engagement. This research thus argues that not enough attention has been paid to the effects of citizenship education policy on students and students’ active citizenship learning in China. This thesis examines the civic experience of university students in China in the parallel contexts of widespread adoption of mass media and of university citizenship education courses, which have been explicitly mandatory for promoting civic morality education in Chinese universities since 2007. This research project raises significant questions about the meditating influences of these two contexts on students’ perceptions of civic knowledge and civic participation, with particular interest to examine whether and how the notion of cultural citizenship could be applied in the Chinese context and whether it could provide certain implications for citizenship education in China. University students in one university in Beijing contributed to this research by providing both quantitative and qualitative data collected from mixed-methods research. 212 participants contributed to the questionnaire data collection and 12 students took part in interviews. Guided by the theoretical framework of cultural citizenship, a central focus of this study is to explore whether new forms of civic engagement and civic learning and a new direction of citizenship understanding can be identified among university students’ mass media use. The study examines the patterns of students’ mass media use and its relationship to civic participation, and also explores the ways in which mass media shape students and how they interact and perform through the media use. In addition, this study discusses questions about how national context, citizenship tradition and civic education curricula relate to students’ civic perceptions, civic participation and civic motivation in their enactment of cultural citizenship. It thus tries to provide insights and identify problems associated with citizenship courses in Chinese universities. The research finds that Chinese university students can also identify civic issues and engage in civic participation through the influence of mass media, thus indicating the application of cultural citizenship in the wider higher education arena in China. In particular, the findings demonstrate that students’ citizenship knowledge has been influenced by their entertainment experiences with TV programs, social networks and movies. However, the study argues that the full enactment of cultural citizenship in China is conditional with regards to characteristics related to two prerequisites: the quality of participation and the influence of the public sphere in the Chinese context. Most students in the study are found to be inactive civic participants in their everyday lives, especially in political participation. Students express their willingness to take part in civic activities, but they feel constrained by both the current citizenship education curriculum in universities and the strict national policy framework. They mainly choose to accept ideological and political education for the sake of personal development rather than to actively resist it, however, they employ creative ways online to express civic opinions and conduct civic discussion. This can be conceptualised as the cultural dimension of citizenship observed from students who are not passively prescribed by traditional citizenship but who have opportunities to build their own civic understanding in everyday life. These findings lead to the conclusion that the notion of cultural citizenship not only provides a new mode of civic learning for Chinese students but also offers a new direction for configuring citizenship in China. This study enriches the existing global literature on cultural citizenship by providing contemporary evidence from China which is a developing democratic country, as well as offering useful information for Chinese university practitioners, policy makers and citizenship researchers on possible directions for citizenship understanding and citizenship education. In particular, it indicates that it is important for efforts to be made to generate a culture of authentic civic participation for students in the university as well as to promote the development of the public sphere in the community and the country generally.