onshore northern perth basin - 1995, page-8

Borrks,
you might want to read up on Fracking..

http://www.crainscleveland.com/article/20120214/BLOGS03/120219920&template=mobile

There's a download link there.. i cant post it for some reason it wont copy on and past on this android device..

anyway.. look at page 48.. that will give you an idea of "then and now"
And I am sure there will be plenty more chime in with some good info for you to read..

If you are unsure on this science I suggest you spend some time reading. As it could be worth your while..