Focus on Shallow Gas Systems

Abstract

Recent exploration activities in two of the largest deltas in the world, the still active Nile delta and the Cenozoic Southern North Sea (SNS) deltas, proved the potential of shallow gas resources. However, shallow gas production is still limited due to a lack of understanding of this gas system. For both the Nile and the SNS delta, there is an on-going debate about the origin of the gas. For both settings, the origin of shallow gas may be deep subsurface thermogenic sources, microbial sources in shallower strata, or a mixture of both. The origin of shallow gas was studied in the Dutch SNS delta as part of a comprehensive multidisciplinary workflow developed and applied to enhance the quantitative knowledge and understanding of the shallow gas play in the delta (Ten Veen et al., 2014). Timing and quantification of microbial gas generation in the SNS delta was studied using a combination of different modeling approaches, and included new detailed basal and surface thermal boundary conditions. Modeling results indicate that intra SNS delta deposits are an important source of microbial gas that are able to fill most of the available traps in the Dutch SNS delta.