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We have tested an amplitude-based multiazimuthal approach for mapping fractures which requires only a simple azimuth-offset sorting process. By displaying the amplitudes of all traces collected within a superbin, the method predicts fractures by mapping P-wave amplitude variations, in which a lineation within the map indicates the presence and the orientation of fractures within the superbin. Test results using physical model and field data sets suggest that the amplitude-based multiazimuthal approach could help to determine the presence of multiple fracture sets in a single layer, which may be expressed through subtle variations in P-wave multiazimuthal seismic reflections. Our experiments with a physical model containing manmade vertical fractures suggest that transmission effects could be one of the dominant factors which control azimuthal amplitude versus offset (AVO) behavior. The technique described in this paper can operate on any 3D P-wave seismic data with wide azimuth and offset distributions.

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Fracture-induced anisotropy can lead to observable azimuthal variations of seismic attributes that then can be used for characterizing a fracture system. Unfortunately, abnormal transmission losses along raypaths also can result in similar azimuthal variations leading to uncertainty in such fracture determination. Using a physical model containing gas-filled fractures, we investigate the impact of abnormal transmission loss on fracture detection from ultrasonic data in a laboratory setting. Recorded reflection amplitudes and traveltimes are used to study ultrasonic responses to the presence of the gas-filled fractures and to understand observed azimuthal attribute anomalies. Experimental results from this study highlight the pitfalls in using azimuthal attribute variations as indicators of the presence of fractures when abnormal transmission attenuation is significant.

Core velocity measurements are an essential part of any 4D seismic feasibility study. During recently conducted core velocity measurements, we found some interesting results regarding velocity anisotropy and hysteresis. These findings include: (1) the stress sensitivity of velocity varies depending on the propagation direction, (2) velocities measured during loading have a significantly larger stress sensitivity than those measured during unloading, and (3) horizontal effective stress has a noticeable impact on velocity anisotropy. We conducted rock physics analysis and 1D seismic forward modeling, incorporating velocity anisotropy, and found that the estimated 4D seismic signal is largely affected by velocity anisotropy and hysteresis. These findings suggest the importance of considering the velocity measurement direction and the nature of the stress change to obtain a realistic 4D seismic signal. Neglecting these considerations may lead to a significantly underestimated or overestimated modeled seismic response.

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Reservoir properties can be inferred from the amount of anisotropy estimated from seismic data. Unfortunately, irregularities in the formations above the reservoir unit can mask or overprint the true seismic anisotropy of the reservoir unit. This overburden effect subjects the measured reservoir seismic anisotropy to a high degree of uncertainty. We investigate this overburden effect on P-waves with a three-layer ultrasonic laboratory-scale model whose middle layer contains localized, gas-filled vertical fractures. We analyze the reflection amplitudes and traveltimes of a P-wave reflection event from below the overburden to understand the overburden effect on anisotropy analysis and imaging. Our study shows that steps must be taken to reduce the P-wave overburden effect when significant irregularities occur in the formations above the reservoir unit.

The aminated collagen fiber (ACF) was prepared by modifying collagen fiber (CF) with ethylenediamine and cynuric chloride as crosslinking agent. The appropriate modification conditions were optimized by single factor experiment method. The reaction molar ratio of CNC and -NH2 was 1.4, the reaction time of ice water bath was 3h, the temperature of the second phase was 45°C and the reaction time was 4h, the temperature of the third phase was 70°C and the reaction time was 3h. The content of amino of collagen fiber and aminated were measured by the method of salicylaldehyde. The structures of collagen fiber and aminated collagen fiber were characterized by SEM and FTIR respectively. The adsorption capacities and the content of amino of CF and ACF were observed by dealing with acidic black dyeing and sturgeon skin dyeing wastewater.