Ontologies can support a variety of purposes, ranging from capturing the conceptual knowledge to the organisation of digital content and information. However, information systems are always subject to change and ontology change management can pose challenges. In this sense, the application and representation of ontology changes in terms of higher-level change operations can describe more meaningful semantics behind the applied change. In this paper, we propose a fourphase process that covers the operationalization, representation and detection of higherlevel changes in ontology evolution life cycle. We present different levels of change operators based on the granularity and domainspecificity of changes. The first layer is based on generic atomic level change operators, whereas the next two layers are user-defined (generic/domainspecific) change patterns. We introduce layered change logs for the explicit operational representation of ontology changes. We formalised the change log using a graph-based approach. We introduce a technique to identify composite changes that not only assists in formulating ontology change log data in a more concise manner, but also helps in realizing the semantics and intent behind any applied change. Furthermore, we identify frequent change sequences that are applied as a reference in order to discover reusable, often domainspecific and usagedriven change patterns. We describe the pattern identification algorithms and evaluate their performance.