Oil and gas well emergency closure - by liquefied gas cooling hydrocarbon below freezing point

摘要

Wells which produce oil and/or natural gas at a high pressure and offshore wells have to be closed by other means if the conventional safety devices like blow-out preventers have failed. This can be achieved by converting the oil or natural gas by cooling into a solid phase and/or by solidifying the moisture contained in it to ice. This prevents disastrous pollution of the environment. The pref. means of cooling the casing near the well mouth is liquefied gas (nitrogen) which is introduced in the well or riser through a lateral auxiliary borehole which seals well within minutes.