Published:January 01, 2011
This paper uses three-dimensional seismic data to investigate the typologies, genetics, and mechanisms of soft-sediment deformational processes on the Ebro Continental Margin (offshore northeastern Spain). The study focuses on the two major types of soft-sediment deformation in the region: slope failure and fluid-escape structures. Such processes have operated almost continuously throughout the post-Pleistocene history of the Ebro Continental Margin, and have played a critical role in its overall evolution and construction. This study shows that vertical stacking patterns of submarine canyons create preferential pathways for fluid migration and slope failure. In these areas, three-dimensional seismic analysis reveals a potential cause-and-effect relationship between focused fluid migration and repeated slope failure. The proposed model is that focused fluid flow from sands within stacked submarine canyons leads to overpressure generation and reduction of sediment shear strength, making sediment susceptible to failure. The presence of a widespread region of fluid-escape structures and slope failures on the Ebro Continental Margin has important implications for offshore facilities. The relatively high resolution provided by the seismic data has been sufficient to be used for a geohazard assessment study, aimed at exploratory well design and field development. The results from this study have led to a detailed program of seafloor and near-surface evaluation over a proposed area in the area.
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Mass-Transport Deposits in Deepwater Settings
Historically, submarine-mass failures or mass-transport deposits have been a focus of increasingly intense investigation by academic institutions particularly during the last decade, though they received much less attention by geoscientists in the energy industry. With recent interest in expanding petroleum exploration and production into deeper water depths globally and more widespread availability of high-quality data sets, mass-transport deposits are now recognized as a major component of most deep-water settings. This recognition has lead to the realization that many aspects of these deposits are still unknown or poorly understood. This volume contains twenty-three papers that address a number of topics critical to further understanding mass-transport deposits. These topics include general overviews of these deposits, depositional settings on the seafloor and in the near-subsurface interval, geohazard concerns, descriptive outcrops, integrated outcrop and seismic data/seismic forward modeling, petroleum reservoirs, and case studies on several associated topics. This volume will appeal to a broad cross section of geoscientists and geotechnical engineers, who are interested in this rapidly expanding field. The selection of papers in this volume reflects a growing trend towards a more diverse blend of disciplines and topics, covered in the study of mass-transport deposits.