New Tools for Geohazards- Combining Reservoir Evaluation Tools and Seismic Geomorphology to Improve the Interpretation of the Shallow Section

摘要

Interpreters of deepwater 3-D seismic data have adopted orrndeveloped seismic geomorphologic techniques to makerngeohazard assessments. The overall quality and reliability ofrngeohazards assessments based on map-view interpretations ofrn3-D seismic data have made them much more useful forrnmaking important well planning decisions for deepwaterrnexploration/development wells than from interpretations basedrnonly on 2-D and/or traditional analogue geohazards data.rnAlthough far superior to traditional geohazards analysis, thernassessments do not provide quantitative information aboutrnimportant and difficult deepwater geohazard problems such asrnshallow water flow (SWF) and buried gas hydrate that are not,rnor not directly, imaged by amplitudes. Because 3-D seismicrndata is being used for geohazard assessment, other techniquesrnthat use the same data set - such as seismic inversion - mightrnbe successfully applied to SWF and gas hydrate prediction andrnassessment. These seismic inversion techniques have beenrndeveloped and applied to reservoir-level studies previously,rnand have only recently been used for shallow geohazardrnstudies. There are data limitations to applying seismicrninversion to the shallow section, namely the type and qualityrnof the logs that constrain the widespread adaptation of seismicrninversion techniques, although empirical models may be ablernto substitute for these in some cases. This paper describes therncurrent seismic geomorphologic approach taken in geohazardsrnwhen conventional 3-D or high resolution 3-D seismic data arernavailable and briefly reviews work done by others usingrnseismic inversion. In particular, there is an expandedrndiscussion of methods developed by Lu and McMechanrn(2002) and Lu and others (2003) to characterize SWF and gasrnhydrates using inversion methods and a comparison to thernseismic geomorphologic approach to addressing theserngeohazards.