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Results
CO2 Geological Sequestration Modelling and Injection Induced Fracturing Analysis of the Caprock
Liu, X. L. (State Key Laboratory of Hydroscience and Engineering, Tsinghua University) | Lin, P. (State Key Laboratory of Hydroscience and Engineering, Tsinghua University) | Wang, E. Z. (State Key Laboratory of Hydroscience and Engineering, Tsinghua University) | He, G. H. (State Key Laboratory of Hydroscience and Engineering, Tsinghua University) | Han, G. F. (Institute of Mechanics, Chinese Academy of Sciences)
Abstract In geological sequestration, CO2 is injected under high pressure into deep underground rock formations, including deep saline aquifers. This paper presents the invading supercritical CO2-brine two-phase numerical model to describe CO2 flow and transport processes in deep saline aquifers. The effects of anisotropy and different kinds of heterogeneity like horizontal and vertical layers and also existence of barriers between layers on the CO2 flow and transport in a saturated porous media with brine are investigated using the presented two-phase model. Following to simulation results, it can be obtained that the permeability of the rock formations and the permeability anisotropy should be considered as the most important parameters in CO2 flowand transport processes and its distribution in the rock formations. Furthermore, the capillary pressure on the buoyancy-driven flow of CO2 is analyzed, and the XFEM is adopted to simulate the injection induced fracturing process of the naturally fractured caprock. Introduction An ever-increasing amount of scientific evidence suggests that anthropogenic release of CO2 has led to a rise in global temperatures over the past hundreds of years, especially since the Industrial Revolution (Crowley, 2000; Bradley, 2011). Among various greenhouse gases, CO2 is the greatest contributor to global warming. Reducing the concentration of CO2 in the atmosphere is a major challenge to migrate greenhouse gas. Carbon Capture and Sequestration (CCS) is one of the options for mitigating CO2 emission contributing to global warming (Gale, 2002; Baines and Worden, 2004; Pacala and Socolow, 2004; White et al., 2004; Schrag, 2007). CO2 emitted by sources such as power plants is separated and captured, and then is stored underground in geological reservoirs in CCS. Three most viable reservoirs for CO2 storage are deep saline formations, unmineable coal bed seems, and oil or gas reservoirs. While from a capacity perspective, deep saline formations offer significant potential. This approach would lock up the CO2 for thousands of years. Studying the migration behavior of supercritical CO2 and its leakage risk after it is injected into deep saline formations is the main concern in this paper. Injection of CO2 into deep saline formations for the purpose of emission avoidance dates back to the early 1980s. The first large-scale pure CO2 geological sequestration project, Sleipner, was built in 1996. Since then, CO2 geological sequestration has gained increasing attention as a carbon mitigation approach from academia and industry. In the short-term CO2 injection process, the migration of the injected CO2 in geological media is mainly controlled by the buoyancy driven volume flowbecause of its smaller density compared with brine.
- North America > United States (0.28)
- Europe > United Kingdom (0.28)
- Europe > Norway > Norwegian Sea (0.25)
- Geology > Petroleum Play Type (0.75)
- Geology > Geological Subdiscipline (0.69)
- Geology > Rock Type > Sedimentary Rock (0.48)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
- Health, Safety, Environment & Sustainability > Environment > Climate change (1.00)
Theoretical Analysis on Electromagnetic Emission of Rock Fracturing Process
Lin, P. (State Key Laboratory of Hydroscience and Engineering, Tsinghua University) | Liu, X. L. (State Key Laboratory of Hydroscience and Engineering, Tsinghua University) | Kang, S. Z. (State Key Laboratory of Hydroscience and Engineering, Tsinghua University) | Wang, C. (State Key Laboratory of Hydroscience and Engineering, Tsinghua University)
Abstract It is significant to study electromagnetic emission of tensile cracking in rock for seismic science and rock mechanics. The electromagnetic emission during single crack propagation of 2-D rock test specimen is studied. A model to describe the electromagnetic emission during propagation process of single crack is proposed. Hertz array is introduced along the crack surface in this model. The distribution law of electromagnetic field is detected during the rock fracturing process. When ignoring the effect of phase difference, the electromagnetic field during the crack propagation is the spatial overlay of radiation by Hertz oscillators along the fracturing surface. The electromagnetic field created by Hertzian array may be one small part of the actual field. The issue discussed above is complex, systematically and microcosmically study should be done to describe the electromagnetic emission properties of rock material. Introduction Since fracture coalescence study play an important role on understanding the basic failure mechanics of rock. Many extensive research have been done to understand and elucidate crack initiation, propagation, interaction and coalescence by using different materials and methods under different compressive direction since twenties century (Horii, 1985b, Tang, Lin & Wong, 2001, 2003, 2006, 2007). When a solid is fractured, work is performed to create new material surfaces in a thermodynamically irreversible manner. In Griffith's theory (Griffith, 1924) of ideally brittle materials, the work of fracture is spent in the rupture of cohesive bonds. The fracture surface energy, which represents the energy required to form a unit of new material surface, corresponds to a normal separation of atomic planes. The energy required for the rupture of atomic bonds is only a small portion of the dissipated energy in the fracture process. The plastic zone accompanying the crack tip is very small and the physical process of the crack tip has been the focus of much attention. Electromagnetic wave will emerged with rock fracturing, this phenomenon is firstly observed in singular electromagnetic status during earthquake procedure (Warwick, 1982, Parrot, 1985, Fraser Simth, 1990, Adams, 1990). Singular electromagnetic phenomenon occurred during the recent big earthquake. The frequency of the electromagnetic VLF and ULF, and explanation is that electromagnetic field appeared due to redistribution, generation and movement of free charges.