The major geo-hazard for pipelines laid across the continental slope are the sudden and mostly unpredictable downslope soil movement generally called mass gravity flows. Slope failures developing into mass gravity flow that might damage a pipeline is a key issue for pipeline design. Geo-hazard assessment is a multi-disciplinary effort and it involves expertise in geology, geophysics, sedimentology, geotechnics, fluid dynamics and modelling. The present paper presents an integrated approach to assess geo-hazards across the continental slope. In addition to the individual aspects of geo-hazard assessment, such as potential flow pattern recognition, soil properties mapping, slope stability and mass flow modelling, the paper describes the importance of proper planning of the activities, starting at a very early stage to optimise the collection of survey data, and the interaction among the different disciplines, which are not sequentially linked but highly integrated.
Pipeline design across continental slopes has become a major area of interest of ocean engineering as a consequence of the rapid development of Oil & Gas Industry in deep and ultra-deep environments. In this context, the offshore pipeline industry is now offering new or upgraded lay vessels able to reach depths in excess of 1000 metres (lorio et al., 2000). The Continental slopes are geologically complex areas characterised by steeply sloping seabed, irregular bathymetry and locally abundant sediments. Offshore installations in the continental slopes of the Gulf of Mexico, West Africa, the Philippines, the northern margin of the North Sea but also of enclosed basins like the Black Sea and the Caspian Sea have focused the effort of engineers to study this geologically hazardous environments (Niedoroda et al., 2000a, 2000b, Reed et al., 2000). Their efforts are justified by the difficulty of deep sea intervention or protective works, which calls for more restrictive design requirements to ensure reliability over the operating life-span.
