  Starting from Israel equations for the spherically symmetric thin shells we
introduce the effective potential and show how it can be used in constructing,
without further thorough investigation, the corresponding Carter-Penrose
diagrams describing clearly the global geometry of the composite space-time
manifolds. We demonstrate, how this new method works, by considering all
possible configurations for the neutral thin dust shell immersed into different
types of Reissner-Nordstr\"om electro-vacuum manifolds.
