Re: Salt domes

Biswajit Banerjee — Thu, 24 Jul 2008 01:54:52 -0400

I was hoping for someone else to chime in before I did. But since there seems to be no comers yet let me give it a shot. Caveat: I've looked at the deformation of salt pillars when mined but never at the behavior of in-situ salt.

Whether you want treat the salt as a non-Newtonian fluid or as a solid depends on the time scale that you're interested in (see Deborah number in Wikipedia and other more reliable sources). Also, it's hard to determine whether a material will fracture if you treat it as a fluid that can essentially wrap around itself many times without cracking - think lava before it cools enough to crack. The solid-fluid intermediate stage is a fascinating but largely unstudied domain in the mechanics literature.

If you're dealing with small timescales, a viscoelastic-plastic model is probably the better way to go. Salt creeps considerably under pressure but doesn't flow as readily as lava.

The interface between the cap rock and the salt is best modeled as a frictional contact surface (when you're using solid mechanics) but as a no-slip bc when you're calling the salt a fluid. Unless there is a thin layer of water at the interface which lubricates the flow, I would expect a significant amount of friction and probably cracking due to that.

I'll try to come up with a better response if I get the time.

-- Biswajit

iMechanica - salt domes - Comments

Re: Salt domes