Ah but they're not drilling oil and gas wells - just a hole to a lake.
There's quite a difference in the scale of difficulty - particularly when it comes to extraction and transport.
And notice how much it has cost. You need to have good probabilities of discovering very large reservoirs before it's a commercial proposition.
Or improved drilling techniques.
As I said, it's an engineering problem and it will be solved, but the return needs to be there (or the strategic imperitive due to lack of other secure supply).