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Introduction to Geo-hazards in Deep Water and Associated with Exploration Around Salt

John Dribus
Schlumberger

Abstract

Following the lead of the US BOEMRE, the oil and gas industry has been following a three-step approach to addressing various drilling hazards that may be encountered in deep water: Identification, Prevention, and Mitigation. This presentation focuses on an important additional step: Understanding the geologic origin of hazards. By relating the near surface and subsurface geological hazards to the petroleum system which has filled the basin over time and hopefully charged the prospect with commercial hydrocarbons, we can better understand when to expect various hazards. This talk reviews the geologic origin, characteristics, and behaviors of the three main deep water hazard types recognized by the US BOEMRE:

  • Man-made surface hazards including linear geometry and single site geometry hazards.
  • Sea-floor geologic hazards including pockmarks, mud volcanoes, unstable slopes, mass sediment movement, and reefs, buildups, and salt cap rock.
  • Sub-surface geologic hazards including shallow water or gas flows, reactivated faults, gas chimneys, gas hydrates, and centroid effect.

In addition, potential drilling hazards often associated with massive and layered salt are reviewed including possible problems drilling in to top of salt, drilling through massive and layered salt complexes, and emerging from salt into rubble zones, feeders, or other potential hazards.

AAPG Search and Discovery Article #90200 © AAPG Geoscience Technology Workshop, Fifth Annual AAPG-SPE Deepwater Reservoir, January 28-29, 2014, Houston, Texas