3D Structural Frameworks: The Gold Standard in Subsurface Interpretation

Thomas Neely
ConocoPhillips, Houston, TX

Abstract

Accurate 3D models of the deformed subsurface are foundational to successful oil & gas exploration and development, and modeling 3D structural complexity in the subsurface requires specific skills and software. The gold standard in modern structural interpretation is the Structural Framework: an air-tight network of fault and horizon surfaces that completely describes the three-dimensional structural geometry of a given area, field, or prospect. The specific geometry of fault systems, basin margins, and other deformed regions are more likely to be accurately captured in a structural framework because their construction workflow promotes sculpting mental models into physical products. Within E&P settings, structural frameworks can only be built using volumetric seismic/well/data interpretation software that allow for complete geometrical descriptions using incomplete data sets.

Although building a structural framework requires skills in both structural interpretation and spatial thinking, there is a strong business case for allocating time and resources to construct hi-fidelity 3D models. Geologic maps or models that are not built within a 3D environment commonly contain errors that misrepresent the size and nature of a prospect or play fairway, or the degree and complexity of faulting therein. The "2.5D" workstation workflow for mapping and understanding fault systems, for instance, is outdated and introduces uncertainty to a given interpretation because geometric validity of fault intersections, terminations, etc … cannot be visually QC'd. Furthermore, nearly all advanced structural analyses, including fault-seal analysis, stress prediction, and fracture modeling require robust 3D models at their foundation. The examples provided here demonstrate the power and utility of structural frameworks in oil & gas exploration and development, and are testament to their role as the standard in structural interpretation as the industry explores in increasingly challenging geological settings in the 21st century.

AAPG Search and Discovery Article #120140© 2014 AAPG Hedberg Conference 3D Structural Geologic Interpretation: Earth, Mind and Machine, June 23-27, 2013, Reno, Nevada