Applications for evaluation of physical properties - An example of siliceous rock permeability -

Abstract:

ODP Leg. 186, two sites (Site 1150 and Site 1151) were drilled on the continental slope of the deep-sea forearc basin of northern Japan. Diatomaceous sediments were recovered Site 1150 and Site 1151, and the depth of each site is 1181.60 mbsf and 1113.60 mbsf, respectively. This area is under the influence of the Oyashio current and is one of the highly bio-productive regions of the North Pacific Ocean (Motoyama et al., 2004). The combination of high productivity and active tectonic deformation that often caused high rate accumulating of fossil and organic rich sediments. Likewise, IODP Exp. 341 was implemented on off South Alaska. Pelagic and MTD ‘s layer were recognized with IRD(Ice Rafted Debris).

In Tohoku, The onboard results of porosity measurements show high value (50-70 %) down to 1000 mbsf, and obviously higher than nearby subduction trench, Nankai Trough (Taylor and Fisher, 1993). There is a possibility that diatomaceous shell keep a frame structure from effective stress and load pressure. On another drilling site result, DSDP Leg. 19 located 60 km to the north of ODP sites, was reported high value of porosity, but recognized only shallow range (>500 mbsf) (Shephard and Bryant, 1980). Also, South Alaska sediments show high sedimentation rate and cyclic MTD's Layer. Permeability was lower than Tohoku sediments in spite of upper depth.

We focused on the relationships between physical property, microstructure, and logging data at deep range(-1000 mbsf). Logging data were collected using wireline logging (Sacks and Suyehiro, 2003; IODP Prel. Rept., 341., 2014). Based on these results, it is expected that microstructure and logging can be integrated into a general model of core-log correlation.

In this presentation, We show results of microstructure using SEM, measured physical properties, and wireline logging data, respectively.