--> Abstract: Structural and Stratigraphic Controls on Fracture System Architecture: An Example from the Carmel Formation of the San Rafael Swell, Utah, by M. P. Fischer; #90937 (1998)

Datapages, Inc.Print this page

Abstract: Structural and Stratigraphic Controls on Fracture System Architecture: An Example from the Carmel Formation of the San Rafael Swell, Utah

FISCHER, MARK P., Department of Geology, Northern Illinois University, DeKalb, IL 60115-2854

The architecture of fracture networks is described by a number of parameters, including fracture spacing, aperture, length, height, connectivity, filling, orientation, and style (i.e. joints versus shear fractures). Accurate, early characterization of such fracture system parameters is essential for successful exploration and production of fractured reservoirs, but these characterizations are often difficult to make, because the fracture system architecture can be strongly affected by a number of structural or stratigraphic variables. Ongoing work is aimed at developing methods to predict fracture system architecture using limited surface and subsurface data. This paper presents early results of work on fracture systems in Laramide-style folds using mechanical stratigraphy and four-dimensional surface analysis.

The San Rafael swell is a classic Laramide-style uplift exposing Jurassic through Cretaceous rocks in east-central Utah. Within the east-facing limb of the San Rafael monocline, the Carmel Formation can be divided into 10 mechanical units based on stratigraphic characteristics and style of deformation. In so doing, a consistent correlation between fracture system architecture and bed thickness, bedding style and rock type is apparent. In addition, observations of structural fabrics and cross-cutting relations allow the interpretation of a simple kinematic history for this portion of the monocline involving early cross-strike compression and later strike-normal and strike-parallel extension. This sequence of deformation is not consistent throughout a vertical section, however, suggesting different kinematic histories for units at initially different depths. To explain the origin of this variability, results of simple models of the 4D evolution of Laramide-style folds are presented.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah