Horizontal natural gas storage caverns and methods for producing same

A method of producing a storage cavern in a naturally-occurring underground salt formation, the method comprising:

• drilling a first bore hole from an above-ground surface location into the underground salt formation;
• slanting the first bore hole during drilling to produce an elongate conduit extending along a substantially horizontal plane in the underground salt formation;
• inserting a blocked off end of a pipe string into the first bore hole;
• introducing a length of the pipe string, comprising holes of predetermined size at predetermined spacings, into the elongate conduit;
• charging solvent for salt to the pipe string so that the solvent exits from the holes;
• and
• leaching salt from the salt formation around the pipe string to create a cavity extending into the salt formation, said cavity substantially completely surrounded by walls comprising formations of salt.

A method of producing a storage cavern for gaseous material in a naturally-occurring underground salt formation, the method comprising:

• introducing a perforated pipe string, in a substantially horizontal plane, into the salt formation;
• supplying solvent, at controlled rates, through holes of predetermined size at predetermined spacings in said pipe string;
• and
• leaching salt from the salt formation around the pipe string to produce a cavity extending into the salt formation, said cavity substantially completely surrounded by walls comprising formations of salt.