Data report: permeability of sediments from Sites C0011 and C0012, NanTroSEIZE Stage 2: subduction inputs

Abstract

Constant rate of strain (CRS) consolidation experiments and flowthrough permeability experiments are used to characterize the flow behavior of hemipelagic mudstones at Integrated Ocean Drilling Program Sites C0011 and C0012. Flow-through permeability experiments on samples from Site C0011 (366.76-687.15 meters below seafloor [mbsf]) provide estimates of vertical permeability (k v) that range from 7.03 × 10-17 to 1.38 × 10-18 m 2. Flowthrough experiments on samples from Site C0012 (273.51-473.11 mbsf) provide estimates of in situ k v from 6.09 × 10-19 to 2.86 × 10-19 m 2 and in situ horizontal permeability (k h) of 6.54 × 10-19 m 2. At Site C0012 (115.44-255.31 mbsf), CRS-based estimates of in situ k v range from 1.12 × 10-17 to 2.54 × 10-18 m 2 and in situ k h ranges from 1.66 × 10-17 to 6.55 × 10-18 m 2. For the four depths at Site C0012 where vertical and horizontal permeability calculations were made, the permeability ratio (k v /k h) ranges from 0.38 to 0.99. Where calculated, k v /k h does not show any depth trends. Neglecting one anomalous data point, all data show permeability decreases with increasing depth and decreasing porosity. Flowthrough data document greater permeability at Site C0011 compared to Site C0012 at equivalent depths below 350 mbsf. In lithologic Units III and IV, permeability estimated by flow-through experiments at Site C0011 is greater than at Site C0012. Drilling and coring disturbance exists in all samples and adjacent shipboard samples, suggesting that all permeability estimates have been impacted by sample disturbance, should be viewed with caution, and should be considered an upper limit on in situ permeability. the overall research objectives of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) to constrain, monitor, and understand faulting and seismogenesis along megathrusts (Tobin and Kinoshita, 2006).

Consolidation state of incoming sediments to the Nankai Trough subduction zone: Implications for sediment deformation and properties

“…Shipboard porosity data are shown in Figures a and c for comparison [ Saito et al ., ; Henry et al ., ]. In situ permeabilities reported in other studies [ Hüpers and Kopf , ; Dugan and Zhao , ] are shown in Figures b and d for comparison (triangles).…”

“…For all of our samples, permeability varies log‐linearly with porosity at stresses above (i.e., during plastic yielding in virgin compression) (Figures c–f). All of the mudstone samples from both Sites C0011 and C0012 exhibit similar relationships between permeability ( k ) and porosity ( ϕ ), as also documented in the previous studies on mudstones and shales [ Neuzil , ; Gamage and Screaton , ; Skarbek and Saffer , ; Screaton and Ge , ; Hüpers and Kopf , ; Reece et al ., ; Dugan and Zhao , ; Screaton et al ., ]. The best‐fit relation to our data for mudstone samples is .…”

“…We estimated the in situ porosity and permeability for each sample from our experimental data by taking measured values at stresses equal to (computed from shipboard bulk density measurements and assuming hydrostatic pore pressure) (Figure and Table ) [e.g., Long et al ., ; Hüpers and Kopf , ; Dugan and Zhao , ]. For CRS tests, we extracted values of porosity and permeability from the experimental data for each experiment at stresses equal to for that sample; for triaxial and IL tests, we interpolated based on the trends defined by measurements for each experiment.…”

“…The estimated in situ permeability of the sandstones ranges from 10 −13 to 10 −15 m 2 , and does not vary systematically with depth (Figures b and d). Our estimates of in situ permeability are consistent with the previous studies (e.g., Figure , open triangles) [ Hüpers and Kopf , ; Dugan and Zhao , ].…”

Nuclear magnetic resonance characterization of shallow marine sediments from the Nankai Trough, Integrated Ocean Drilling Program Expedition 333

“…To determine the permeability at the initial porosity, the sample is consolidated sufficiently to obtain virgin consolidation, and the permeability-porosity data from the virgin consolidation portion of the test are extrapolated back to the initial porosity using a log linear fit. Further details on CRS tests and their interpretations can be found in Daigle and Dugan [2009], Daigle and Dugan [2011b], and Dugan and Zhao [2013]. Permeabilities determined from CRS experiments ranged from 2.3 × 10 À14 m 2 to 5.9 × 10 À19 m 2 , generally decreasing with depth.…”