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Flexible Kinematic Modeling Approaches Informed by Observations From Mechanical Forward Models and Natural Structures

Abstract

Successful petroleum exploration in structurally complex geologic settings depends upon construction of the best possible interpretations of incomplete subsurface data. Studies that investigate how geologic structures at this scale form, and how best to characterize their geometries, can serve to improve decision-making and confidence in subsurface interpretation, thus reducing exploration trap risk, and has further implications for the resultant distribution of sub-seismic strain associated with these structures.

In spite of the demonstrated value of these approaches to exploration, both kinematic and mechanical modeling approaches have shortcomings that limit the extent to which they may be practically applied in the description of natural structures. Emergent forward mechanical models, though often able to lend insight into the mechanical conditions leading to the formation of a general structural style, commonly are unable to reproduce the exact geometry of a specific natural structure. This is partially the result of the computationally intensive nature of the approach which limits the range of models that can realistically be run. Conversely, while kinematic models have been developed such that the specific geometry of a natural structure may be matched, limitations of existing derived kinematic solutions with simple end-member structural geometries restricts their application in more complex cases.

In this study, we demonstrate how observations from natural structures and general mechanical models developed using the discrete element method may be used to inform specific modifications to kinematic assumptions—for instance, the activity of simultaneous slip on multiple faults, and the deviation of axial surfaces from orientations that preserve layer thickness during contraction. We show how modifications such as these can be incorporated into a velocity field-based numerical representation of the kinematics of fault-related folding. Through this integrated approach, we are able to rapidly match the geometry of more complex natural structures through kinematic models that encompass a broader range of structures yet which are informed by mechanical plausibility. This improves the explorationist’s ability to create robust structural interpretations in a larger variety of geologic circumstances. The ability to rapidly generate diverse forward kinematic models provides a framework for the future ability to invert for complex structures.