Ahhh, the Internet...
...will it ever run out of whackos?
This is one of those cases (Like the time cube) where I wonder whether the writer believes what they're writing, or they're just having a bit of fun.
As for the abnormally high natrual gas (methane) presence in the well fluid: All oil wells contain some gas, it's normally sealed off in the cementing phase. If it isn't sealed off, it tends to overwhelm the oil production, since the gas is much lower viscosity and density, it produces preferentially. Given that there's a good chance that the cementing in the well didn't go as planned (If it had, nothing would be leaking,) there's a good possibility that the gas zone wasn't sealed off.
Now how a 20 mile bubble results from a well that was only 5 miles deep... That's a true mystery to me. And how exactly does escaping fluid cause the sea bed to rise? The pressure driving the fluid out has been there for millenia, and now that it's got an outlet, it'll be lowering (slightly.)
I personally will skip the bunker.