GeoReservoir: An ontology for deep-marine depositional system geometry description.

An ontology is a logical theory that accounts for a domain vocabulary's intended meaning, allowing us to develop a computational artifact that explicitly and formally represents the community's conceptualization related to a vocabulary. This paper presents the GeoReservoir ontology - the result of the ontological analysis of the terminology adopted by geologists in sedimentological studies about deep-marine depositional systems, which is one of the most relevant types of oil and gas reservoirs around the world. Despite the variety of studies describing the patterns of productive reservoirs, this domain demanded new approaches in conceptual modeling methodologies because the available terminology presents issues such as ambiguity and contamination of different interpretations in the terms' definitions. Previous work has dealt with these issues in geology, resulting in the GeoCore, an ontology that explicitly defines the most generic entities in geology. However, the domain in focus still demanded a specialized ontology containing the particular terms found in reports about deepmarine deposits. GeoReservoir is an extension of GeoCore, which, in its turn, extends the Basic Formal Ontology (BFO), a foundational ontology for scientific domains. GeoReservoir takes advantage of both BFO and GeoCore's foundations, allowing us to focus our effort on defining the domain-specific entities. A team of professional reservoir geologists supported the knowledge acquisition process. We developed the ontology in iterative steps from an initial prototype to a complete artifact containing the taxonomy of entities and the relations between the entities, being increasingly refined by the experts. We further present a case study demonstrating how one could describe a depositional system in GeoReservoir terms. Moreover, we validated the ontology against defined competency questions (CQs). This work's final result is offering a sound, consistent and unambiguous terminology to support the integration of data and knowledge about deep-marine depositional system geometry and lithology.