The authors obtained good estimates of measured velocities of sand-peat samples at low pressures by using a theoretical method, the self-consistent theory of Berryman (1980), using sand and porous peat to represent the microstructure of the mixture. They were unable to obtain useful estimates with several other theoretical approaches, because the properties of the quartz, air and peat components of the samples vary over several orders of magnitude. Methods that are useful for consolidated rock cannot be applied directly to unconsolidated materials. Instead, careful consideration of microstructure is necessary to adapt the methods successfully. Future work includes comparison of the measured velocity values to additional theoretical estimates, investigation of Vp/Vs ratios and wave amplitudes, as well as modeling of dry and saturated sand-clay mixtures (e.g., Bonner et al., 1997, 1998). The results suggest that field data can be interpreted by comparing laboratory measurements of soil velocities to theoretical estimates of velocities in order to establish a systematic method for predicting velocities for a full range of sand-organic material mixtures at various pressures. Once the theoretical relationship is obtained, it can be used to estimate the soil composition at various depths from field measurements of seismic velocities. Additional refining of the …

The conference has covered new developments in all aspects of the science, technology and use of accelerators. All individuals with an interest in particle accelerators were invited to attend.

Effective seismic interrogation of the near subsurface requires that measured parameters, such as compressional and shear velocities and attenuation, be related to important soil properties. Porosity, composition (clay content), fluid content and type are of particular interest. The ultrasonic (100-500 kHz) pulse transmission technique was used to collect data for highly attenuating materials appropriate to the vadose zone. Up to several meters of overburden were simulated by applying low uniaxial stress of 0 to about 0.1 MPa to the sample. The approach was to make baseline measurements for pure quartz sand, because the elastic properties are relatively well known except at the lowest pressures. Clay was added to modify the sample microstructure and ultrasonic measurements were made to characterize the effect of the admixed second phase. Samples were fabricated from Ottawa sand mixed with a swelling clay (Wyoming bentonite). The amount of clay added was 1 to 40% by mass. Compressional (P) velocities are low (228-483 m/s), comparable to the sound velocity in air. Shear (S) velocities are about half of the compressional velocity (120-298 m/s), but show different sensitivity to microstructure. Adding clay increases the shear amplitude dramatically with respect to P, and also changes the sensitivity of the …

The goal of this project is to improve the efficiency of miscible CO2 floods and enhance the prospects for flooding heterogeneous reservoirs. This report provides results of the second year of the three-year project that will be exploring three principles: (1) Fluid and matrix interactions (understanding the problems). (2) Conformance control/sweep efficiency (solving the problems. 3) Reservoir simulation for improved oil recovery (predicting results).