Fracture Characterization Using Azimuthal AVO, Ant-Tracking and Curvature

Li, Yandong (PetroChina Company Limited) | Wang, Jun (PetroChina Company Limited) | Yang, Hao (PetroChina Company Limited) | Zhang, Yan (PetroChina Company Limited) | Zheng, Xiaodong (PetroChina Company Limited)



Seismic AVOA method, which employs P-wave amplitude variation with incident angle and acquisition azimuth, is a powerful tool for fracture characterization in HTI medium. However, this azimuthal AVO based fracture characterization approach is only applicable to fracture set with single dominant orientation, which is not always true in real applications. Ant tracking is able to delineate small scale discontinuities, which has a close relationship to fractures. Curvature is also a popular method for fracture characterization. In this paper, we perform fracture characterization by comprehensively utilizing azimuthal AVO, ant tracking and curvature analysis. We select optimal incident angle range for azimuthal AVO based fracture inversion. To make full use of wide azimuth seismic data, we perform ant tracking on six azimuthally sectored seismic volumes and then combine the results together to better delineate fractures set with multiple orientations. Curvature attribute is also introduced as a useful aid to AVOA and ant-tracking for fracture characterization. We applied this integrated fracture characterization scheme to Tarim Basin, Northwest China. Application results showed that there is a good accordance in the results produced by AVOA, multi-azimuth seismic volume ant-tracking, and curvature. The estimated fracture orientation was verified by image log data. These results indicate that the proposed method is effective in fracture characterization.