I should have used the term 'dark pool'.

The dark pool gets its name because details of these trades are concealed from the public, clouding the transactions like murky water. Some traders that use a strategy based on liquidity feel that dark pool liquidity should be publicized.

About the other well? Who knows, secrecy is the name of the game when it comes to the Mako trough. This article will give you an idea.

http://agoracom.com/ir/Falcon/forums/discussion/topics/307946-enough-for-100-years-%E2%80%93-secrecy-is-abundant-around-the-mako-gas-field/messages/1056398#message