000			02643nab a2200241 4500
005			20260520000317.0
008			260224s2014 xxu ing
041			_aInglés
245	0	0	_aNatural fractures in shale _bA review and new observations
260			_a _b _cnov. 2014
270			_a09/12/2014 ; 09/12/2014
300			_a51 p. ; 2165-2216
520			_aTranscripción del resumen del autor: Natural fractures have long been suspected as a factor in production from shale reservoirs because gas and oil production commonly exceeds the rates expected from low-porosity and low-permeability shale host rock. Many shale outcrops, cores, and image logs contain fractures or fracture traces, and microseismic event patterns associated with hydraulic-fracture stimulation have been ascribed to natural fracture reactivation. Here we review previous work, and present new core and outcrop data from 18 shale plays that reveal common types of shale fractures and their mineralization, orientation, and size patterns. A wide range of shales have a common suite of types and configurations of fractures: those at high angle to bedding, faults, bed-parallel fractures, early compacted fractures, and fractures associated with concretions. These fractures differ markedly in their prevalence and arrangement within each shale play, however, constituting different fracture stratigraphies—differences that depend on interface and mechanical properties governed by depositional, diagenetic, and structural setting. Several mechanisms may act independently or in combination to cause fracture growth, including differential compaction, local and regional stress changes associated with tectonic events, strain accommodation around large structures, catagenesis, and uplift. Fracture systems in shales are heterogeneous; they can enhance or detract from producibility, augment or reduce rock strength and the propensity to interact with hydraulic-fracture stimulation. Burial history and fracture diagenesis influence fracture attributes and may provide more information for fracture prediction than is commonly appreciated. The role of microfractures in production from shale is currently poorly understood yet potentially critical; we identify a need for further work in this field and on the role of natural fractures generally.
581			_a11
773	0		_tAAPG Bulletin _g98
942			_cARTICULO
100	1		_aGale, Julia F.W. _938548
100	1		_aLaubach, Stephen E. _942957
100	1		_aOlson, Jon E. _912292
100	1		_aEichhubl, Peter _919605
100	1		_aFall, András _952917
999			_c188703 _d188703