f Monitoring of an underground flow by sea bottom seismic instruments - A case study

In January 1989, when drilling a deep Jurrasic well in the Southern North Sea, offshore Norway, Saga Petroleum a.s had to shut in the well by activating the BOP. The semisubmersible rig was moved off the location and a relief well was spudded. When a jack-up rig was reconnected to the well three months later, the pressure in the well had dropped considerably, indicating internal underground flow.