Abstract

With the movement of offshore exploration into deeper waters, the risk ofencountering geohazards has become much greater. Fortunately, recent advancesin sonar technology, positioning capabilities, and computer processing powerhave revolutionized the way we can image and explore the deep seafloor and thusdirectly address the issue of deepwater geohazards. At the core of thesetechnologies has been the development of multibeam sonar and 3-D seismicsystems that can provide near 100 percent coverage of relatively large areas ofthe seafloor with high resolution. The massive amounts of data produced bythese systems present many challenges, but also offer tremendous opportunitiesin terms of visualization and analysis. Interactive 3-D visualization andexploration tools specifically designed to facilitate the interpretation andanalysis of very large (10's to 100's of megabytes), complex, multi-componentspatial data sets collected during exploration and site surveys. These toolsoffer a powerful new approach to addressing the problems of geohazard riskassessment and mitigation. If properly georeferenced and treated, complex datasets can be presented in a natural and intuitive manner that allows theintegration of multiple components, each at their inherent level of resolution, and without compromising the quantitative nature of the data. Artificialsun-illumination, shading, and 3-D rendering can be used with digitalbathymetric data (DTM's) to form natural looking and easily interpretable, yetquantitative, landscapes. Color can be used to represent depth or otherparameters (like backscatter or sediment properties) which can be draped overthe DTM, or high-resolution imagery can be texture mapped on bathymetric orsubsurface data. When combined with interactive analytical tools, this approachcan greatly increase the speed and confidence with which deepwater hazards canbe assessed and mitigated.

Introduction

As offshore exploration pushes into deeper and deeper waters the risk ofencountering geohazards is rapidly increasing. The relatively benignenvironment of most shallow water exploration and production is quickly givingway to the unstable, steep slopes, density flows, and gas hydrate zones of thecontinental slope and upper rise. It is the combination of processes that makethese deeper water areas viable hydrocarbon prospects (high sedimentationrates, potential for trap formation, etc) that also adds to the potential riskof geohazards. As depths increase, the cost of all aspects of exploration andproduction increase and with this, the financial impact of losses associatedwith geohazards takes on increasing significance.

The answer does not lie in simple scaling. Traditional survey techniques usedfor shallow water exploration and site survey lose resolution (both horizontaland vertical) with increasing water depth and thus are not adequate foridentifying deepwater geohazards1. Fortunately, with the push into deep waterhas come the development of an array of new technologies which, when broughttogether, can give us an unprecedented ability to explore, in high-resolution, the geohazard potential of the deep seafloor.

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