Modeling of Multi-Scale Fracture Networks from Satellite Imagery and Field Measurements in the Cambrian Umm Ishrin Formation, Jordan
Hydrocarbon production from fractured reservoirs can be unpredictable and analogue outcrop studies are often used to help understand how fracture networks influence fluid flow in these reservoirs. Principal properties of fracture systems such as acoustic properties, permeabilities, and geomechanic parameters, are all 3-D tensors. Field studies should therefore have the aim to capture the full 3-D fracture system. The highly fractured sandstones of the Cambrian Umm Ishrin Formation in Jordan are chosen in this study as an analogue because of their excellent “near 3-D” exposures and their properties representative of reservoir rocks. The formation consists mainly of massive fluvial sandstones interbedded with thin floodplain shales, offering an opportunity to investigate the impact of these geomechanical discontinuities on the vertical connectivity of the fractures. Multiple tectonic phases have reactivated and overprinted older fracture networks, the sequences of which are unravelled by relative and absolute age dating.
A multi-scale approach is taken to characterize and quantify the fracture system. High-resolution QuickBird images are used to interpret the large- to medium-scale fractures. Automatic lineament detection supported by manual quality control is carried out to maximize the quality of the interpreted fractures. Medium- to small-scale fractures are quantified in the field using conventional fracture measurement techniques and an unbiased digital GIS-method, recently developed in this research project.
Three distinct fracture sets are identified on representative vertical and horizontals outcrops. These mostly 2-D data are assembled in a stochastic way to form a 3-D fracture model. Fracture domains are defined as compartmentalized areas bounded by large-scale fracture corridors. The smaller-scale fracture sets observed within these domains are aligned with the orientation of the bounding fractures. Fluid flow modeling shows that the bounding fracture corridors form the principal fluid conduits across the entire stratigraphic column, while the floodplain shales act as flow barriers for the smaller scale fractures. These results can be used to improve the understanding of and possibly predict local reservoir properties below seismic resolution in inter-well areas across a fractured reservoir.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009