000 02552nab a2200217 4500
005 20260608201743.0
008 260224s2013 xxu ing
041 _aInglés
100 1 _aMilliken, Kitty L.
_913547
100 1 _aRudnicky, Mark
_952951
100 1 _aAwwiller, David N.
_952952
100 1 _aZhang, Tongwei
_952953
245 0 0 _aOrganic matter-hosted pore system, Marcellus Formation (Devonian), Pennsylvania
260 _a
_b
_cfeb. 2013
270 _a30/10/2013 ; 30/10/2013
300 _a23 p.
520 _aTranscripción del resumen del autor: The Marcellus Formation of Pennsylvania represents an outstanding example of an organic matter (OM)-hosted pore system; most pores detectable by field-emission scanning electron microscopy (FE-SEM) are associated with OM instead of mineral matrix. In the two wells studied here, total organic carbon (TOC) content is a stronger control on OM-hosted porosity than is thermal maturity. The two study wells span a maturity from late wet gas (vitrinite reflectance [Ro], ~1.0%) to dry gas (Ro, ~2.1%). Samples with a TOC less than 5.5 wt. % display a positive correlation between TOC and porosity, but samples with a TOC greater than 5.5 wt. % display little or no increase in porosity with a further increasing TOC. In a subset of samples (14) across a range of TOC (2.3-13.6 wt. %), the pore volume detectable by FE-SEM is a small fraction of total porosity, ranging from 2 to 32% of the helium porosity. Importantly, the FE-SEM-visible porosity in OM decreases significantly with increasing TOC, diminishing from 30% of OM volume to less than 1% of OM volume across the range of TOC. The morphology and size of OM-hosted pores also vary systematically with TOC. The interpretation of this anticorrelation between OM content and SEM-visible pores remains uncertain. Samples with the lowest OM porosity (higher TOC) may represent gas expulsion (pore collapse) that was more complete as a consequence of greater OM connectivity and framework compaction, whereas samples with higher OM porosity (lower TOC) correspond to rigid mineral frameworks that inhibited compactional expulsion of methane-filled bubbles. Alternatively, higher TOC samples may contain OM (low initial hydrogen index, relatively unreactive) that is less prone to development of FE-SEM-detectable pores. In this interpretation, OM type, controlled by sequence-stratigraphic position, is a factor in determining pore-size distribution.
773 _g
942 _cARTICULO
999 _c187942
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