Modern software systems are highly configurable in order to satisfy diverse customer requirements and application contexts. Feature models provide a well-established formalism for tailoring configuration spaces of applications. Thereupon, multi-view staged configuration approaches modularize feature models for separation of concerns and apply workflow modeling for scheduling configuration decisions. However, the complex, often oblivious and even cyclic logical dependencies among configuration decisions obstruct compositional semantics of feature model views thus spoiling intuitive modeling and rigorous analysis of staged configuration processes. In this paper, we apply workflow Petri nets (WPNs) as a formal operational model for staged configuration that makes explicit causal dependencies among feature selections. For the internal separation into composable configuration stages we further adopt the principles of open workflow nets. It is shown that the soundness notion of WPNs naturally coincides with fundamental correctness and liveness properties to be verified for staged configuration processes. We present a prototype implementation for an automated computation of staged configuration processes and provide experimental results concerning scalability properties.