Sketch-based geological modelling with flow diagnostics: the digital back-of-the-envelope for 3D geology and subsurface flow

Sketch-based geological modelling with flow diagnostics provides an interactive and intuitive prototyping approach to quickly build geomodels and generate quantitative results to evaluate volumetrics and flow behaviour. This approach allows users to rapidly test the sensitivity of model outputs to different geological concepts and uncertain parameters, and informs selection of geological concepts, scales and resolutions to be investigated in more detailed models. Here we apply the sketching and prototyping approach to different aspects of geo-energy modelling and use in geoscience and engineering training. Rapid Reservoir Modelling (RRM) is a free open-source sketch-based geological modelling tool with an intuitive interface that allows users to rapidly sketch geological models in 3D (bitbucket.org/rapidreservoirmodelling/rrm). Geological models that capture the essence of heterogeneity of interest and related uncertainty can be created within minutes. Geological operators ensure correct truncation relationships between these 3D surfaces by the modelling engine. Flow diagnostics then computes key indicators of predicted flow and storage behaviour within seconds. Example use cases and how models can be shared, will be discussed, including: (1) Scenario screening to identify heterogeneities with the most impact on CO2 storage. Capturing uncertainty in geological concepts cannot be achieved by changing a numerical variable but can be varied easily by sketching the different concepts, such as lateral connectivity, continuity and geometry of geological heterogeneities that act as flow barriers and pathways. Capturing multiple different concepts in conventional modelling approaches is time-consuming and in practice not often carried out. (2) Use of mini-models and hierarchical models to derive effective properties. Models with varying complexity of heterogeneity are sketched at smallest relevant scale, and effective properties are calculated. Calculated effective properties can then be used to populated models sketched at larger scale. Sketching is free of existing restrictive templates, realistic subsurface models can be generated easily. (3) Training of geoscientists and engineers to investigate the impact of geological interpretations on storage volumes and connectivity. Geomodels addressing all three aspects are constructed and analysed quickly, using simple, geologically intuitive workflows that do not require prior geomodelling expertise. However, using conventional modelling packages, the learning curve to create or adapt a geological model is steep and long and can distract from training objectives. Using intuitive sketch-based approach the entry point to creating a geological model is much more accessible while still maintaining the key learning, i.e. impact of geology on subsurface applications.