[Balding_Eagle]

The type of wells that are (were) being drilled are known for the steep decline rates.

That is also true of oil pulled from storage in salt domes, although I would guess the decline rate is much steeper from the salt dome.

[crusty old prospector]

To hollow out a salt dome would take quite a while. You would have to continually pump fresh water into it and then dispose of the brine. It can be done but it would take a while.