Gas and fluid injection triggering shallow mud mobilization in the Hordaland Group, North Sea
Published:January 01, 2003
Helge Løseth, Lars Wensaas, Børge Arntsen, Martin Hovland, 2003. "Gas and fluid injection triggering shallow mud mobilization in the Hordaland Group, North Sea", Subsurface Sediment Mobilization, P. Van Rensbergen, R. R. Hillis, A. J. Maltman, C. K. Morley
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During a regional seismic interpretation study of leakage anomalies in the northern North Sea, mounds and zones with a highly chaotic seismic reflection pattern in the Tertiary Hordaland Group were repeatedly observed located above gas chimneys in the Cretaceous succession. The chaotic seismic reflection pattern was interpreted as mobilized sediments. These mud diapirs are large and massive, the largest being 100 km long and 40 km wide. Vertical injections of gas, oil and formation water are interpreted to have triggered the diapirs.
On the eastern side of the Viking Graben, another much smaller type of mud diapir was observed....
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Subsurface Sediment Mobilization
Sedimentary facies in the subsurface are usually interpreted from a epositional/stratigraphical perspective: the depositional layering is generally considered to remain undisturbed, except in a few settings. But, there is growing evidence that subsurface sediment mobilization (SSM) is more widespread than previously thought, as new observations arise from the ever-increasing resolution of subsurface data. Many examples are from hydrocarbon provinces but studies elsewhere, for example in preparation for the underground storage of hazardous waste, have yielded unexpected examples. Although until now the different aspects of SSM, including soft sediment deformations, sand injections, shale diapirs, mud volcanoes, etc, have been separated, the new discoveries emphasize their inter-connection, regardless of scale, depth, location, grain size or trigger mechanism. This volume integrates the different aspects of sediment mobilization in the subsurface and their structural consequences, allowing a more generaland a more coherent view of the subject.