The figure shows typical gas-hydrate-related drilling and production problems encountered during drilling programs in the Arctic (from Collett and Dallimore 2002). Gas release scenario (left): over-pressured free gas is encountered unexpectedly beneath a gas hydrate layer. Gas leakage scenario (centre): possible disturbance of gas hydrate by drilling that has dissociated gas hydrate and caused free gas migration outside of the drill casing. Collapsed casing scenario (right): possible disturbance of gas hydrate caused by conventional production of warm hydrocarbon at depth.
From collection: Frozen Heat - A Global Outlook on Methane Gas Hydrates