TY - JOUR
T1 - In Situ Permeability and Scale Dependence of an Active Accretionary Prism Determined From Cross-Borehole Experiments
AU - Kinoshita, C.
AU - Saffer, D. M.
N1 - Funding Information:
This work was supported by NSF grants OCE-0623633 and OCE-1334436 to D. S. Robert Valdez provided his experimental data shown in Figure 5 and supporting information. Y. Kano and J. Mori provided useful comments that improved this paper. This research used pressure data from IODP Hole C0002G, which is shown in supporting information, and can be downloaded directly (http://offshore.geosc.psu.edu). We used the Generic Mapping Tools (GMT) software (Wessel & Smith,) for the preparation of figures.
Funding Information:
This work was supported by NSF grants OCE-0623633 and OCE-1334436 to D. S. Robert Valdez provided his experimental data shown in Figure 5 and supporting information. Y. Kano and J. Mori provided useful comments that improved this paper. This research used pressure data from IODP Hole C0002G, which is shown in supporting information, and can be downloaded directly (http://offshore.geosc.psu.edu). We used the Generic Mapping Tools (GMT) software (Wessel & Smith, 1991) for the preparation of figures.
Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.
PY - 2018/7/28
Y1 - 2018/7/28
N2 - Permeability controls fluid flow in the Earth's crust and affects a wide range of processes including advective transport and pore pressure generation. However, in situ measurements of permeability are few, especially in active tectonic settings or at scales relevant to regional flow. We analyze formation fluid pressure records from oceanic boreholes in the Nankai accretionary prism offshore southwest Japan, focusing on unexpected responses to drilling operations conducted at boreholes ~100 m to the northeast. We develop a 2-D numerical model of transient fluid flow and conduct a parametric grid search to define hydraulic diffusivity. A value of 0.19–0.46 m2/s (corresponding to a permeability of 9.8 × 10−13 to 2.4 × 10−12 m2) yields the best fit to observed pressure responses. Together with laboratory measurements on core samples and drillstrem tests reported in previous studies, our analysis indicates a strong scale dependence of permeability, likely reflecting the presence of permeable faults and fractures.
AB - Permeability controls fluid flow in the Earth's crust and affects a wide range of processes including advective transport and pore pressure generation. However, in situ measurements of permeability are few, especially in active tectonic settings or at scales relevant to regional flow. We analyze formation fluid pressure records from oceanic boreholes in the Nankai accretionary prism offshore southwest Japan, focusing on unexpected responses to drilling operations conducted at boreholes ~100 m to the northeast. We develop a 2-D numerical model of transient fluid flow and conduct a parametric grid search to define hydraulic diffusivity. A value of 0.19–0.46 m2/s (corresponding to a permeability of 9.8 × 10−13 to 2.4 × 10−12 m2) yields the best fit to observed pressure responses. Together with laboratory measurements on core samples and drillstrem tests reported in previous studies, our analysis indicates a strong scale dependence of permeability, likely reflecting the presence of permeable faults and fractures.
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U2 - 10.1029/2018GL078304
DO - 10.1029/2018GL078304
M3 - Article
AN - SCOPUS:85051008834
SN - 0094-8276
VL - 45
SP - 6935
EP - 6943
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 14
ER -