Abstract: Fitting the Pieces Together: The Major Challenge in Creating Useful 3D Earth Models of Hydrocarbon Reservoirs

Raphael Mayoraz, Robert C. Belcher

The analysis and understanding of hydrocarbon reservoirs is often made difficult by the absence of a consistent 3D earth model. The key issue is the treatment of faults. By treating faults as 2D polygons or center lines, traditional mapping does not address the problem of consistently propagating faults through multiple layers, thereby creating 3D geometrical inconsistencies which unnecessarily complicate problems.

More recent attempts to create 3D models introduce powerful 3D surface modeling capabilities but still do not provide the necessary tools for managing the organization of large numbers of surfaces, namely horizons and faults, that typify most hydrocarbon reservoirs. More importantly, users must identify surface intersections and manually truncate fault and horizon models.

In a new solution, geologic objects are treated as they occur in nature: faults as surfaces and layers as volumes. This new technology uses a user-defined set of geologic relationships (fault hierarchies and geologic rules) to build a consistent 3D earth model. Fault and horizon intersections are automatically calculated in 3D, and surface models are appropriately truncated. This approach opens new doors for 3D modeling: the consistency of faulting is honored during time-to-depth migration of horizons; the computation of intermediate surfaces is automatic; the computation of 3D property distributions with or without regard to the complexly faulted layers is now possible; and finally, geospatial contour maps, cross sections, volumetrics, and output data for reservoir simulators can be erived from the 3D earth models with significantly improved consistency and precision.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France