改进的方位各向异性地震反演裂缝预测技术及应用

在有限(窄)方位各向异性叠前地震反演裂缝预测技术中,如何克服噪音对反演结果的影响,一直是地震反演预测裂缝中的难题。通过对Rüger公式的近似、简化与改进,有效分离地震数据中的有效信号和噪音的效果。在地震反演中,结合成像测井解释裂缝成果,选定最合理的压噪因子参与反演计算。采用该计算方法预测裂缝密度与方位分布,不仅与成像测井吻合率较高,而且为井间裂缝预测提供了可靠的依据。在塔里木盆地YB1井区奥陶系鹰山组碳酸盐岩裂缝储层预测中应用效果较好,成功预测出该区裂缝主要在断层附近较发育,在构造隆起的东北部,裂缝发育程度较高,是该区油气进一步勘探开发的有利区域。

Improved seismic azimuth anisotrophy inversion method and its application in fracture prediction

Broad azimuth seismic anisotropy inversion method is reliable and effective in predicting the fracture in reservoirs. However, in most cases the acquired seismic data are of narrow azimuth, which can be easily affected by noise in seismic inversion. Hence, it is important to reduce the noise in developing the narrow azimuth seismic inversion method. In this paper, the Ruger Equation is transformed into two parts representing the effective signal and the noise in seismic data, and then the noise effects are effectively suppressed during seismic inversion process. To achieve optimal results, a reasonable noise suppression factor has been derived from the image logging interpretation. Using this method, the reservoir characteristic of fracture density and fracture azimuth can be better detected and predicted. This is because it not only improves the consistency with the image logging, but also gives more reliable predictions for the areas away from the wells. This method has been successfully applied to the Yubei1 well block of Tarim Basin in detecting the fractures in carbonate reservoirs of the Yingshan Formation, Ordovician. The prediction results confirms that the north-eastern part of the main structure has developed massive fractures indicating favorable hydrocarbon potentials for further exploration and development in the next step.