Seismic Chimney Formation Induced by Upward-migrating Methane in the Nordland Group, Southern Viking Graben

Abstract

The Nordland Group in the Southern Viking Graben hosts seismic chimneys, represented by anomalies in seismic data and resid- ual methane accumulations. These anomalies are generally interpreted as focused fluid flow structures, and thus pose the risk of potential fluid leakage by geological subsurface utilization. Our aim was to assess if excess pore pressure, resulting from buoy- ancy effects due to upward-migrating methane in the Utsira Formation may be responsible for formation of these anomalies. Our hydromechanical simulation results demonstrate that tensile failure in the Nordland Group already occurs before the maximum methane column heights develop in the Utsira Formation below.