--> Abstract: Fracture Density Modeling Using GIS: Implications for the Development of Throughgoing Fracture Zones and Subsurface Fluid Flow, by Michael R. Gross, Martin D. Finn, Dean Whitman, and German Y. Ojeda; #90914(2000)
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Michael R. Gross1, Martin D. Finn1, Dean Whitman1, German Y. Ojeda1
(1) Florida International University, Miami, FL

Abstract: Previous HitFractureNext Hit Density Modeling Using GIS: Implications for the Development of Throughgoing Previous HitFractureNext Hit Zones and Subsurface Fluid Flow

Two dimensional Previous HitfractureNext Hit density maps were created from surface exposures of the Monterey Formation, California, using Geographic Information Systems technology. The rocks underwent an early phase of extensional faulting followed by a late phase of compression. A prominent set of vertical bed-confined joints trending 010 developed in conjunction with late phase compression, followed by a later set of cross joints striking 308. Large, multilayer Previous HitfractureNext Hit zones cut through the outcrops, extending vertically and horizontally for tens of meters. These Previous HitfractureNext Hit zones strike NNW-SSE, have apertures ranging from 10 - 50 cm, contain blocks of fractured rock within tar matrix, and are the dominant permeability conduits for offshore production in the Santa Maria basin. One may initially misinterpret the Previous HitfractureNext Hit zones as faults due to their brecciated appearance and geometries resembling pull-aparts. However, close inspection reveals the Previous HitfractureNext Hit zones are extensional features that developed by the linkage of pre-existing bed-confined joints.

GIS software was used to digitize fractures from photographs and then to perform a spatial density Previous HitanalysisNext Hit of each Previous HitfractureNext Hit set as well as the total Previous HitfractureNext Hit network. Spatial Previous HitfractureNext Hit densities vary dramatically according to Previous HitfractureNext Hit set, lithology, and proximity to Previous HitfractureNext Hit zones. Most importantly, high contour intervals of Previous HitfractureNext Hit densities are often aligned in linear patterns parallel to the trend of large Previous HitfractureNext Hit zones, even in areas devoid of apparent Previous HitfractureNext Hit zones. Therefore, spatial Previous HitanalysisNext Hit of fractures may serve as a valuable technique to predict the orientation and density of hydrologically significant Previous HitfractureTop zones.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana