Determination of the Relationships of Electrical Resistivity, Sound Velocity, and Density/Porosity of Sediment and Rock by Laboratory Techniques and Well Logs from Deep Sea Drilling Project Sites 415 and 416 off the Coast of Morocco

Abstract

Comparisons of compressional-sound velocity and its relationship to wet-bulk density from well-log data with those of laboratory data, from depths of 113 meters to 273 meters below sea floor in Miocene nannofossil marl and chalk, indicate that the porosities of laboratory samples are about 5 porosity units greater than those of in situ sediments (or on the logs). This is in agreement with predictions by Hamilton (1976) for porosity rebound with the release of overburden pressure. The electrical-resistivity relationship with porosity agrees well with the Archie (1942) type relationship. The models, in decreasing order of agreement are: Boyce (1968), Archie (1942), Kermabon et al. (1969), Winsauer et al. (1952), andMaxwell (1904). In general, acoustic anisotropy increases with age and depth. Anisotropy is typically 0 to 5 per cent (maximum of 14%) faster parallel to bedding in Tertiary sediments, from 0 to 661 meters below the sea floor, and typically 0 to 30 per cent in mainly Mesozoic sedimentary rock, from 661 to 1624 meters. Acoustic anisotropy is particularly significant (0.4 km/s or greater) when velocities are from 2.0 to 4.2 km/s.

Carolina Slope Sites 1054 and 1055

“…50), which is expected for increasingly compacted sediment. Resistivity is a function of the porosity and tortuosity (and, to a lesser extent, mineralogy) of sediments (Boyce, 1980). The general trend of increasing resistivity with depth below seafloor is consistent with the index properties results of decreasing porosity with depth (Fig.…”

Electrical Resistivity, Sound Velocity, Thermal Conductivity, Density-Porosity, and Temperature, Obtained by Laboratory Techniques and Well Logs: Site 462 in the Nauru Basin of the Pacific Ocean

“…In general, the GRAPE data appear to be slightly higher. Considering all the assumptions of grain densities and attenuation coefficients, as discussed in Boyce (1976a), however, the correlation of the data is good.…”

“…The wet-water content, wetbulk density, and porosity of a sub-sample were then determined by weighing the water-saturated sample in water and after drying for 24 hours at 110°C. The weight of evaporated water was corrected for salt content (35‰) to give the weight of sea water (Boyce, 1976a;Boyce, Appendix I, this volume;Hamilton, 1971b). The estimated precision of wet-bulk density is ±0.01 g/cm 3 (absolute), and the precision of wet-water content and porosity is ±0.5% absolute units.…”

“…The "formation factor-porosity" relationship is of particular interest because there are only a few published studies of modern unconsolidated marine sediments (Boyce, 1968(Boyce, , 1980Kermabon et al, 1969;and Don-nelly et al 1980). For a summary of various types of lithology and their F-porosity relations, see Keller (1966) and Keller and Frischknecht (1966).…”

“…Basalt pore-water resistivities do not appear to be greatly different from sea water. Formation factors are greater than those derived from equations in Maxwell (1904), Winsauer et al (1952), Boyce (1968), and Kermabon et al (1969). An "apparent interstitial water resistivity" (i?J curve was derived from the density and induction logs.…”