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Deep-Water Seabed Characterization Using Geostatistical Analysis of High Density/High Resolution Previous HitVelocityNext Hit Field

 

Cauquil, Eric1, Vincent Curinier1, Stéphanie Legeron-Cherif2, Florent Piriac2, Alain Leron2, Nabil Sultan3 (1) Total, Paris La Défense, France (2) ERMS (3) IFREMER

 

Deepwater geohazards present geophysical signatures including interval Previous HitvelocityNext Hit anom­alies, with high Previous HitvelocityNext Hit for gas hydrates / hardground and low Previous HitvelocityNext Hit for gas bearing sed­iments. This paper describes a methodology for regional geohazard assessments using geo­statistical analysis of high density / high resolution (HDHR) Previous HitvelocityNext Hit field.

A 3D HDHR Previous HitvelocityNext Hit field is obtained using Total’s internal Previous HitvelocityNext Hit picking software (DeltaStack3D) that picks Previous HitvelocityNext Hit automatically at every CDP gather. Time sampling, depending on seismic frequency content, is driven by the definition of constraints along a seed line which are propagated in 3D in order to take into account lateral geological varia­tions. The interval Previous HitvelocityNext Hit cube is then computed from this RMS Previous HitvelocityNext Hit field.

From this interval Previous HitvelocityNext Hit field, ERMS applied a standard Spatial Quality Assessment (SQA) procedure using geostatistics, with spatial analysis of Previous HitvelocityNext Hit data, estimation (fac­torial kriging) of “possible artefacts” and “geological” spatial components, and derivation of Spatial Quality Index (SQI„¥, patented by ERM.S). Final products are interval Previous HitvelocityNext Hit charts, where filtered residuals could detect small scale geological features.

Previous HitVelocityNext Hit anomaly charts have been compared to in-situ geotechnical measurements con­ducted by IFREMER with PENFELD (deep water CPT). A total of 21 CPT and sonic measure­ments have been acquired over the study area, allowing detection of gas, gas hydrates lay­ers and carbonate concretions. The comparison between HDHR Previous HitvelocityNext Hit field and in situ measurements showed a very good correlation.

This geostatistical analysis of HDHR Previous HitvelocityTop field calibrated on in situ measurement pro­vides a relevant methodology for regional deep water seabed characterisation.