Geospatial Modeling: A Breakthrough 3-D Technology for Understanding Complexly Faulted Geologic Structures

Karen S. Hoffman and Robert Belcher

Today's geoscientists are required to find hydrocarbons in increasingly complicated geologic structures. These structures are usually faulted and contain complex geometric relationships. Their complexity requires modeling and mapping capabilities beyond traditional surface mapping tools.

Geospatial modeling enables geoscientists to create models of complex geologic structures, calculate distributions of properties therein, visualize models in three dimensions, and analyze models through volumetric calculations. Faults and horizons are treated as individual surfaces in three-dimensional space. Fault relationships are controlled by hierarchies, and relationships between stratigraphic layers are specified by simple geologic rules. The following features can thus be accommodated: depositional layers; layers truncated by unconformities; layers cut by channels; channel in-fill; and salt diapirs. Although the resulting model is calculated from a fixed set of geological relationships, input data may change as data are added or existing interpretations altered, allowing for qu ck update. Property models may be calculated for each layer and/or each fault block. The three-dimensional property modeling utilizes fault and horizon surfaces as boundaries. Properties are correctly calculated near faults and show appropriate displacements across faults. Unique three-dimensionally consistent contour maps and cross sections are extracted from the models. The three-dimensional contouring process determines the spatial extent of layers, defines geometries of fault and unconformity truncation wedge zones, and accurately portrays fault gaps.

Increased success is important in today's market. Geospatial modeling technology can address the sizeable problems facing geoscientists working with complexly faulted geologic structures, and can significantly increase overall understanding in a timely manner.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California