000			02109nab a2200205 4500
005			20260520000224.0
008			260224s2009 xxu
245	0	0	_aNatural fracture characterization in tight gas sandstones _bIntegrating mechanics and diagenesis
260			_a _b _cnov. 2009
270			_a17/06/2010 ; 17/06/2010
300			_a16 p. ; 1535-1550
520			_aTranscripción del resumen del autor. Accurate predictions of natural fracture flow attributes in sandstones require an understanding of the underlying mechanisms responsible for fracture growth and aperture preservation. Poroelastic stress calculations combined with fracture mechanics criteria show that it is possible to sustain opening-mode fracture growth with sublithostatic pore pressure without associated or preemptive shear failure. Crack-seal textures and fracture aperture to length ratios suggest that preserved fracture apertures reflect the loading state that caused propagation. This implies that, for quartz-rich sandstones, the synkinematic cement in the fractures and in the rock mass props fracture apertures open and reduces the possibility of aperture loss on unloading and relaxation. Fracture pattern development caused by subcritical fracture growth for a limited range of strain histories is demonstrated to result in widely disparate fracture pattern geometries. Substantial opening-mode growth can be generated by very small extensional strains (on the order of 10–4); consequently, fracture arrays are likely to form in the absence of larger scale structures. The effective permeabilities calculated for these low-strain fracture patterns are considerable. To replicate the lower permeabilities that typify tight gas sandstones requires the superimposition of systematic cement filling that preferentially plugs fracture tips and other narrower parts of the fracture pattern.
581			_a11
773	0		_tAAPG Bulletin _g93
942			_cARTICULO
100	1		_aOlson, Jon E. _912292
100	1		_aLaubach, Stephen E. _942957
100	1		_aLander, Robert H. _931913
999			_c171181 _d171181