HAL : hal-00554879, version 2

arXiv : 1101.2295

DOI : 10.1029/ 2011JB008565

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Journal of Geophysical Research 116 (2011) B12201

Versions disponibles :

v1 (12-01-2011)

v2 (27-03-2012)

4D imaging of fracturing in organic-rich shales during heating

Maya Kobchenko 1, Hamed Panahi 1, Francois Renard 1, 2, Dag Kristian Dysthe 1, Anders Malthe-Sorenssen 1, Adriano Mazzini 1, Julien Scheibert 1, 3, Bjorn Jamtveit 1, Paul Meakin 1

(07/12/2011)

To better understand the mechanisms of fracture pattern development and fluid escape in low permeability rocks, we performed time-resolved in situ X-ray tomography imaging to investigate the processes that occur during the slow heating (from 60° to 400°C) of organic-rich Green River shale. At about 350°C cracks nucleated in the sample, and as the temperature continued to increase, these cracks propagated parallel to shale bedding and coalesced, thus cutting across the sample. Thermogravimetry and gas chromatography revealed that the fracturing occurring at ~350°C was associated with significant mass loss and release of light hydrocarbons generated by the decomposition of immature organic matter. Kerogen decomposition is thought to cause an internal pressure build up sufficient to form cracks in the shale, thus providing pathways for the outgoing hydrocarbons. We show that a 2D numerical model based on this idea qualitatively reproduces the experimentally observed dynamics of crack nucleation, growth and coalescence, as well as the irregular outlines of the cracks. Our results provide a new description of fracture pattern formation in low permeability shales.

1 :	Physics of Geological Processes (PGP)
	University of Oslo
2 :	Institut des sciences de la Terre (ISTerre)
	CNRS : UMR5275 – IFSTTAR – Université de Savoie – Université Joseph Fourier - Grenoble I – INSU – OSUG – IRD : UR219
3 :	Laboratoire de Tribologie et Dynamique des Systèmes (LTDS)
	CNRS : UMR5513 – Ecole Centrale de Lyon – Ecole Nationale d'Ingénieurs de Saint Etienne

Domaine

:

Planète et Univers/Sciences de la Terre/Géophysique Physique/Physique/Géophysique Sciences de l'environnement/Milieux et Changements globaux

Mots Clés : primary migration – X-ray tomography – hydrocarbon – invasion-percolation – fracturing – crack – shale

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Contributeur : Julien Scheibert <>

Soumis le : Mardi 27 Mars 2012, 12:48:18

Dernière modification le : Mardi 27 Mars 2012, 16:52:52