William F. Murphy

Modulus decomposition of compressional and shear velocities in sand bodies

The advent of borehole shear slowness measurements in sonically slow formations has lead to breakthroughs in the subsurface profiling of geological bodies. In sand bodies, compressional and shear velocities depend predictably on porosity, mineralogy, grain contacts, and fluid saturation. An interpretation is best performed by decomposing the velocities into moduli that are intrinsic measures of the rock frame and pore fluid compressibilities. Careful experiments on pure materials (i.e., pure quartz sandstones) demonstrate two simplifying constitutive relationships. First, the bulk and shear frame moduli are simple functions of the porosity. A comparison of the measured shear frame modulus to the prediction for the pure material distinguishes sand from shale. Second, the ratio of the bulk and shear frame moduli is a constant 0.9 independent of the porosity. The measured velocities are directly inverted to yield the bulk modulus of the pore fluid. The fluid saturation effects are so dramatic at high porosit...

THE TRANSIENT SETTLING OF STABLE AND FLOCCULATED DISPERSIONS

An experimental investigation of the sedimentation of monodisperse colloidal silica spheres with grafted octadecyl chains with three different interaction potentials is presented. Small particles (0.27 μm) behaved as hard spheres in cyclohexane, but larger ones (0.60 and 0.94 μm) are weakly flocculated by van der Waals attractions. The smallest particles (0.08 μm) in hexadecane are strongly flocculated by attractions between the octadecyl layers. A medical computer tomography (CT) scanner provided an accurate and absolute density measurement without disrupting the process. For the hard spheres and the weakly flocculated systems, the kinetics of sedimentation for the dispersed phase could readily be predicted utilizing the flux curve. For flocculated networks, we found a power-law relationship between compressive yield stresses and solids fractions comparable with other experimental systems.

High-resolution shallow geophysics and geology in the Hudson-Raritan Estuary Ecosystem Restoration, New Jersey

The Hudson-Raritan Estuary of New York and New Jersey is one of the largest estuaries on the East Coast of the United States. It includes part of the New York City metropolitan area and includes the Port of New York and New Jersey. The estuary is an important economic, environmental, and recreational resource and asset for the region. Fresh water enters the estuary from the Hudson, Hackensack, Passaic, and Raritan rivers. Since the 17th century, the estuary has experienced industrialization and residential growth that have profoundly altered the estuary and surrounding land from its precolonial state.