000			02923nab a2200217 4500
005			20260525052811.0
008			260224s2015 xxu ing
041			_aInglés
100	1		_aHan, Yuanjia _955184
100	1		_aMahlstedt, Nicolaj _955185
100	1		_aHorsfield, Brian _955186
245	0	0	_aThe Barnett Shale _bCompositional fractionation associated with intraformational petroleum migration, retention, and expulsion
260			_cdic. 2015
270			_a03/03/2016 ; 03/03/2016
300			_a29 p. ; 2173-2202
520			_aTranscripción del resumen del autor: The Marathon 1 Mesquite well was drilled in Hamilton County, Texas, targeting the Barnett Shale with late oil window maturity. Combining a large suite of petrologic and high-resolution organic geochemical analyses on 120 core samples, we have been able to document qualitatively and quantitatively the effects of petroleum retention within and expulsion from five intervals within the Barnett Shale. Lithological heterogeneities control the composition and amount of retained fluids; the sorption of oil by solid organic matter is important in all intervals. Applying empirical formulas, we have been able to demonstrate not only that retention is primarily controlled by total organic carbon (TOC), but also that the "live" or "labile" component, rather than "dead" or "inert" carbon, constitutes the most active sorptive sites. Additional retention in the micropores provided by biogenic microcrystalline quartz (sponge spicules) accounts for the sweet spot defined by an "oil crossover" in the 9.14-m (30-ft) thick second interval. The fluorescing oil occurring in the axial chamber of the sponge spicules and that sorbed on organic particles are together enriched in saturated hydrocarbons, whereas the dispersed oil from the adjacent interval 3 is depleted in this compound class. Mass-balance calculations reveal that short-distance migration of petroleum into this "reservoir" interval (second) fractionates the generated oil into a higher quality oil by preferential retention in the order polar compounds > aromatic hydrocarbons > saturated hydrocarbons within the underlying organic matter and clay-rich third interval (source unit). Furthermore, molecular fractionation, i.e., a preferential expulsion of lower molecular weight hydrocarbons (n-alkanes) could be calculated. An additional practical result for source rock assessment is that corrected S2 (petroleum generated by pyrolysis) and TOC values should be calculated by combining Rock-Eval pyrolysis data on whole rocks and rocks following Soxhlet extraction. Using parameters based on unextracted rock only, the expulsion of petroleum is systematically overestimated and the degree of kerogen conversion is, therefore, concomitantly underestimated.
581			_a12
773	0		_tAAPG Bulletin _g99
942			_cARTICULO _2ddc
999			_c189462 _d189462