Multi-Scale Fracture Network Analysis from the Cambro-Ordovician Clastic Sequence in Petra, Jordan — From Outcrop Data to a Conceptual Model

A systematic multi-scale fracture network is prominently exposed in the Cambro-Ordovician sedimentary succession in southwestern Jordan. This succession consists of marine deposits, overlain by heterogeneous deltaic sediments, culminating in 500 m of massive to cross-bedded fluvial sandstones. A data set is acquired from high-resolution satellite imagery and field measurements that enables the quantification of the geometry and spatial characteristics of the fracture network in three dimensions. The fractures are grouped into orders of similar characteristic sizes; from 1st order fractures representing the large- (seismic-) scale discontinuities to 3rd order fractures observed in the field.

Two dominant sets are identified, with a mean strike of N65° and N145°. The presented results are valid for both these sets. 1st order fracture zones, composed of tightly spaced joints confined in fracture swarms, exhibit a log-normal length distribution and are regularly spaced, while the length distribution of 2nd order fractures follows a power-law and the fractures are clustered, reflecting different fracture system styles as a function of scale. The 3rd order fracture network is strongly dependent on the distribution of bedding plane discontinuities throughout different parts of the succession.

We derived a fracture model that provides semi-quantitative relationships between the stratigraphic architecture of the sedimentary sequence and the observed fracture characteristics at different scales. We propose a work flow that describes how these relationships from the analogue fracture model can be combined with sub-surface data to optimize the development of dynamic reservoir models of systematically fractured reservoirs.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California