Although sealing the top of this concrete cylinder may be impossible due to pressure, would it not make it easier to attach a pipe and start collecting the oil?

Although sealing the top of this concrete cylinder may be impossible due to pressure, would it not make it easier to attach a pipe and start collecting the oil? Yes, it would have to be a big pipe, but is that possible? Or, could you not attach a cone to the top of the cylinder to condense the flow into a smaller (pipe size flow)?