Fracture porosity in the décollement zone of Nankai accretionary wedge using Logging While Drilling resistivity data

Bourlange, S.; Henry, Pierre; Moore, J. Casey; Mikada, Hitoshi; Klaus, A.

doi:10.1016/s0012-821x(03)00082-7

Cited by 46 publications

(65 citation statements)

References 29 publications

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“…Deformation between these zones is more sparse and dominated by resistive fractures (Figure 2). It is possible that ''background'' resistive fractures may be bedding planes or compactive shear zones [Bourlange et al, 2003], but their orientations are still relevant to stress analysis.…”

Section: Fracture Resistivitymentioning

confidence: 99%

“…RAB resistivity data show a trend of decreasing resistivity (Figure 2d) and increasing porosity through the décollement zone, in addition to high porosity underlying the zone [Bourlange et al, 2003]. Coupled with low porosity core material [Taira et al, 1991;Moore et al, 2001b], Bourlange et al [2003] suggest a compacted décollement fault zone with dilatant fractures, although core properties may represent isolated clasts rather than bulk properties. Overpressures suggest that sediment permeability is insufficient to allow fluid expulsion [Screaton et al, 2002].…”

Section: Fractures Resistivity and Fluid Flowmentioning

confidence: 99%

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Deformation and in situ stress in the Nankai Accretionary Prism from resistivity‐at‐bit images, ODP Leg 196

McNeill

Ienaga

Tobin

et al. 2004

Geophysical Research Letters

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Borehole resistivity images from ODP Leg 196 allow rapid and complete qualitative assessment of deformation within the toe of the Nankai prism, Japan. Borehole breakouts were common within the prism but prominent in the trench‐wedge unit around the frontal thrust, suggesting reduced sediment strength. Breakouts indicate consistent σ2 orientations (∼050°), compatible with northwesterly convergence. Deformation is dominated by discrete zones, including the frontal thrust and décollement zone. Prism fractures trend ∼NE–SW, consistent with convergence. The décollement shows minimal deformation and the dominant structural trend is ∼N–S. Prism deformation zones are characterized by high resistivity (compaction), whereas the décollement is apparently dilated, both with conductive fractures. Distribution of fracture orientations varies between log units confirming lithologic and rheologic influence. Pore pressure is elevated within the décollement and the misalignment of conductive fractures may reduce permeability.

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Section: Fracture Resistivitymentioning

confidence: 99%

Section: Fractures Resistivity and Fluid Flowmentioning

confidence: 99%

Deformation and in situ stress in the Nankai Accretionary Prism from resistivity‐at‐bit images, ODP Leg 196

McNeill

Ienaga

Tobin

et al. 2004

Geophysical Research Letters

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“…We assumed that the pore fluid was similar to seawater. The formula used to calculate the seawater resistivity (σ f ) as a function of the temperature (in °C) is described by Bourlange et al (2003):…”

Section: Estimation Of Porosity From Resistivity Logsmentioning

confidence: 99%

Methods

2013

Proceedings of the IODP

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“…The water bound to the hydrated minerals is a function of the number of cations present between the layers of hydrated minerals [Ransom and Hegelson, 1994]. The number of cations can be obtained from cation exchange capacity (CEC) measurements [Henry, 1997;Bourlange et al, 2003;Conin et al, 2008]. The effective porosity (' e ) is expressed as…”

Section: Calibration Of Brie Equations For Clays From Iodp Site C0009mentioning

confidence: 99%

Quantification of free gas in the Kumano fore-arc basin detected from borehole physical properties: IODP NanTroSEIZE drilling Site C0009

Doan

Conin

Henry

et al. 2011

Geochem. Geophys. Geosyst.

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[1] The Kumano fore-arc basin overlies the Nankai accretionary prism, formed by the subduction of the Philippine Sea Plate beneath the Eurasian plate offshore the Kii Peninsula, SW Honshu, Japan. Seismic surveys and boreholes within the framework of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) project show evidence of gas hydrates and free gas within the basin. Here we use high-quality borehole sonic data from Integrated Oceanic Drilling Program (IODP) Site C0009 to quantify the free gas distribution in the landward part of the basin. The Brie theory is used to quantify gas content from sonic logs, which are calibrated from laboratory measurements on drill cores. First, we show that the sonic data are Copyright 2011 by the American Geophysical Union 1 of 12 mainly sensitive to the fluid phase filling the intergranular pores (effective porosity), rather than to the total porosity that includes water bound to clay minerals. We then compare the effective porosity to lithodensityderived porosity that acts as a proxy for total porosity. The combination of these two data sets also allows assessment of clay mineralogy of the sediments. Second, we compute free gas saturation and find a gasrich interval that is restricted to a lithological unit characterized by a high abundance of wood fragments and lignite. This unit, at the base of the fore-arc basin, is a hydrocarbon source that should be taken into account in models explaining gas distribution and the formation of the bottom-simulating reflector within the Kumano fore-arc basin.

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Fracture porosity in the décollement zone of Nankai accretionary wedge using Logging While Drilling resistivity data

Cited by 46 publications

References 29 publications

Deformation and in situ stress in the Nankai Accretionary Prism from resistivity‐at‐bit images, ODP Leg 196

Deformation and in situ stress in the Nankai Accretionary Prism from resistivity‐at‐bit images, ODP Leg 196

Methods

Quantification of free gas in the Kumano fore-arc basin detected from borehole physical properties: IODP NanTroSEIZE drilling Site C0009

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