ABSTRACT

Shallow gas, which occurs at depths less than 1000 m below seafloor (Floodgate & Judd 1992), may pose a hazard to offshore open-hole or riser-less drilling operations, such as geotechnical drilling or drilling of the tophole section of oil and gas wells. For this reason, shallow gas hazard assessments are routinely performed prior to geotechnical drilling (Kortekaas & Peuchen 2008). Normally, hazard assessments are based on indications of gas accumulations in geophysical data. When limited or no geophysical data are available, the geological setting can be used to predict whether shallow gas is present.