Natural-gas hydrates are ice-like solids that form when free water and natural gas combine at high pressure and low temperature. This can occur in gas and gas/condensate wells, as well as in oil wells. Detailed reviews of gas-hydrate chemistry, physics, and oilfield engineering are found in Makogon and Sloan. This page focuses on prevention, inhibition, and removal of hydrates in production. Other pages provide more detail on hydrate formation and predicting hydrate formation. Shut-in gas wells are particularly prone to serious hydrate problems, if the well has been producing some water.