We characterize the DARS measurement system in terms of different resonance modes, and 6 sandstone samples were used in the frequency measurements for the fundamental, second and third resonance modes. A least-squares inversion method is used to invert these measured resonance frequencies for the compressibility and density of the sandstones. The compressibilities inverted from different resonance mode frequencies show frequency-dependence for the sandstones with relatively high compressibility, suggesting that the elastic moduli of these samples depend on the frequency of seismic waves. With further accuracy improvement for samples with low compressibility, the DARS technique can be used to quantify the frequency dependence of the acoustic properties of sandstones, which would be beneficial to evaluating attenuation mechanisms of seismic waves propagating through reservoir rocks.
Rock strata usually deform in 3D space in the process of tectonic evolution. With the development of computer technology and 3D visualization technology in recent years, 3D tectonic restoration technology has been widely used in petroleum basin research and exploration. The process of stratigraphic sedimentation is usually sedimentation-compaction-fold-fault. The recovery of 3D paleotectonic is actually the inverse process of stratum sedimentary deformation. Therefore, the process of tectonic restoration can be divided into three steps: de-fault, de-fold and de-compaction. Finally, the depositional state of the target layer without deformation is obtained. The distribution of fractures on the top of buried hill restricts the distribution of high-quality fractured reservoirs. Predicting the distribution of fractures through various ways is the key to finding high-quality reservoirs in buried hill fractured reservoirs. The new and old exploration areas often have enormous and accurate tectonic interpretation information. From the point of view of geomechanics, studying the process of geological tectonic movement and the role of fracture formation, will be the most rapid, direct and effective technology for searching fractured reservoirs, especially for oil areas with tectonic fractures. Note: This paper was accepted into the Technical Program but was not presented at the 2019 SEG Annual Meeting in San Antonio, Texas.
Summary Fractures and vuggy cavities in carbonate reservoirs provide favourable spaces for hydrocarbon accumulation and migration. Identifying them and determining their spatial relationships is a critical task for exploration geoscientists. In view of the features of local strong energy near the areas of fractured-vuggy systems on seismic reflections, we specifically used amplitude curvature attributes to localize these fractures and vugs, and reveal their relative spatial relationships. Amplitude curvature, which is the lateral second-order derivative of the amplitude component in seismic data, contains important information about lateral changes of seismic amplitude. In this study, we integrated the most-positive and most-negative curvature estimates to delineate lineaments and boundaries of fractures and vuggy cavities, and made a combination of multispectral curvature measures to reveal different perspectives of fractured and vuggy systems in carbonate reservoirs in the Tarim Basin, NW China.
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