Donald S. Stone, 2013. "Using Freehand Three-dimensional Drawings to Clarify and Verify Subsurface Structural Interpretations", Application of Structural Methods to Rocky Mountain Hydrocarbon Exploration and Development, Constance N. Knight, Jerome J. Cuzella, Leland D. Cress
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The generation of one or more three-dimensional (3-D), freehand drawings, based on integrated analysis of a two-dimensional (2-D) geologic database (e.g., borehole data, seismic profiles, surface geology, etc.), is proposed here as a rewarding exercise in the development of a final interpretation of subsurface geologic structures. A freehand 3-D drawing based on integration of 2-D interpretive structural contour maps (of at least two horizons) and structural cross sections can clarify and verify the 3-D details of complex subsurface geologic structures, check on the internal consistency of the interpretation, uncover untenable, interpretive, geologic configurations, and highlight possible obscure trap geometries. In some cases freehand 3-D drawings can aid in the visualization of impenetrable 3-D images produced by computer software programs. Isometric projection or linear perspective drawings are generally the most useful kinds of 3-D renditions, but strict adherence to these disciplines is not a requirement in the generation of an initial 3-D sketch. Generating a 3-D image using computer software is dominantly the functional domain of the left hemisphere of the brain (left brain), whereas the generation of freehand 3-D drawings is dominantly the functional domain of the right brain and requires penetrative visualization in the conversion of 2-D data to 3-D imagery. The right brain excels in intuitive, creative, imaginative structural interpretation. Examples of freehand 3-D drawings of complex subsurface and surface geologic structures, both self-generated and from literature, are presented along with some auxiliary 3-D analog modeling methods.
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With increasing industry emphasis on developing “unconventional” tight gas reservoirs and on enhancing recovery from existing fields, geologists are facing diverse challenges in the applications of structural geology. Identifying fracture characteristics within petroleum systems is essential. Understanding the timing of tectonics and the formation of structures is important, as these factors strongly influence hydrocarbon generation, migration, entrapment, and preservation. The purpose in publishing this collection of key papers is to aid future workers in addressing complex interrelationships between structural geology and hydrocarbon exploration and development. The first four chapters of this book focus on structural concepts and techniques. The second part of this book is a collection of Rocky Mountain fault and fracture studies. These well documented studies are valuable reference materials for all petroleum geologists.