I think we have risk with the old wells, but we also have risk with the new wells.
From the studies I have been looking at, even with the good cements, it's quite difficult to get a perfect seal from the well casing to the formation. The more you're going to go in and perf and frac, if you comingle your CBM with your conventional and then come in and perf and frac with the shales...I believe every time you do this you're compromising even a top-quality cement.
I think the best way to assess the cumulative effects of this is to measure the gas migrating through the soils. There are experts in Alberta who have done this research. In fact, many industry players are involved in it, so it could be carefully assessed. Possibly, we would see how good the new cements and the technologies are and improve where the weaknesses are.