While the fracing technology explained in earlier slides has been around for years, gas drillers are now developing and using greatly expanded fracing techniques to use on the Marcellus Shale and other shale formations, and they have started using horizontal drilling technology on shale formations that even further expands the use of these expanded fracing techniques. The most common problems arising out of gas well drilling, even the horizontal drilling of those gas wells that use the expanded fracing technology, will still be those problems explained above regarding drilling and cementing the surface casing etc. (There are also potential problems with where the frac water comes from and what happens to it when it flows back to the surface that are beyond the scope of this slide show.) Although problems caused by the expanded fracing technology in horizontal drilling will be very unusual, there is at least one set of circumstances in which this could happen. Go to this explanation of a possible comment on a well permit for a further explanation of this set of circumstances.