Efficient and competitive provision of service compositions depends both on the composition structure, and on planning and management of computational resources necessary for provision. Resource constraints on the service provider side have impact on the provision of composite services and can cause violations of predefined SLA criteria. We propose a methodology for modeling dynamic behavior of provider-side orchestration provision systems, based on the structure of orchestrations that are provided, their interaction, statistically estimated run-time parameters (such as running time) based on log traces, and the model of resources necessary for orchestration provision. We illustrate the application of our proposed methodology on a non-trivial real world example, and validate the approach using a simulation experiment.