If the hole is 2 miles long, I assume the steam would condense before reaching the top. And I guess lowering the pressure again, so I don’t know if that’s possible. But I’m not a physics expert.
At depth, natural gas is in the liquid phase in the reservoir due to high temperatures and overburden pressure. Once the drillbit penetrates the seal of the formation containing natural gas or other liquids then the gas will begin to be carried up the annulus of the well in the drilling mud to the surface. As it moves closer to the surface it expands and crosses into the bubble point into the gas phase which is the dangerous condition that leads to blowouts and the loss of the well and potentially lives at the surface.
It is important to be able to detect the formation boundaries and to have the mud weight tailored to the expected pressures within the target zones so that blowouts can be avoided. Pre-drill predictions of downhole pressures are made from seismic data and can be extremely accurate, especially when correlated with borehole data from regions with similar geologic history.
I did pre-drill pressure predictions as a geophysicist. Very interesting stuff.
Here is a little info about well control and gas kicks.[0]
