Geological constraints on surface-based models through development of Rapid Reservoir Modelling

Abstract

Surface-based geological modelling (SBM) represents all geological heterogeneity that impacts the spatial distribution of petrophysical properties using surfaces. To create surface-based models, rules are required to govern how surfaces interact such that resulting models are geologically sound. Previous studies used implicit rules or assumptions, often with the requirement that surfaces are created in stratigraphic or hierarchical order. A comprehensive set of explicit and universal rules to govern the interaction of stratigraphic surfaces has yet to be formalised. In this thesis, seven operators are presented that define how stratigraphic surfaces interact for geological modelling such that universal geological rules are obeyed. The operators can be applied through any SBM technique and are independent of geological process, scale and setting. The operators are demonstrated using three hand-drafted examples of siliciclastic and carbonate strata, at centimetre to kilometre scales, using outcrop, seismic and conceptual input data. These universal stratigraphic operators are then implemented in 3D in the sketch-based interface and modelling (SBIM) research prototype software Rapid Reservoir Modelling (RRM). Three case studies are presented using examples of siliciclastic and carbonate strata from different depositional environments, at multiple scales, using seismic, outcrop, and well log data to constrain and guide the sketches. The case studies demonstrate the operators and three different techniques for moving from 2D sketch to 3D model, revealing the flexibility and broad applicability of the operators for SBIM of stratigraphy. Lastly, the stratigraphic operators are leveraged in RRM to create structural models. Test cases are a conjugate fault model and a physical model of a salt-influenced passive margin. Gaps in the applicability of stratigraphic operators for ‘sketch-what-you-see’ structural modelling and diagenesis are identified and future updates to RRM are recommended. RRM is the first SBIM software that allows rapid prototyping of geological reservoir models and represents a step-change for the field.