Field-based structural studies as analogues to sub-surface reservoirs

Abstract This paper examines a number of field analogues to structures in the sub-surface, based mainly on examples from SW Britain. Whereas sedimentological analogues are largely interpreted in terms of a clearly defined sequence of depositional events related to stratigraphy, structures can develop throughout the history of the reservoir and their timing is poorly constrained stratigraphically. This leads to fundamental differences in how the two types of analogues are used. The simplest and most direct use of structural analogues comes from comparison of field structures with those sampled in the sub-surface, where they can guide conceptual development of reservoir models. Many examples of this approach exist from the development of stratabound fracture systems to the formation of linked fault systems and fracture networks. Field analogues also play an important role in the study of sub-seismic structures, providing a link to evidence from core. One new area is the application of topology to the study of fault and fracture networks. Not only does this provide insight into fundamental relationships between structures, such as their relative age and connectivity, but it also provides new methods of analysis of great relevance to the spatial variation and scaling of structures.