马头营凸起馆二段窄薄河道砂体地震识别

南堡凹陷马头营凸起馆陶组二段（Ng₂）河道砂体单砂层厚度薄、宽度窄，河道砂体地震识别难度大。综合运用面元小网格化叠前偏移处理、古地貌恢复、高频等时地层划分与对比及岩心-测井相分析技术、“地震线描”河道砂体追踪、层控波阻抗反演和振幅地层切片等技术对马头营凸起Ng₂ Ⅴ砂层组窄薄河道砂体进行识别。结果表明，地震资料面元尺度由15 m×30 m缩小为7.5 m×7.5 m，提高了地震资料垂向和横向分辨率，增强了曲流河窄薄河道砂体边界识别能力；馆二段为明显的曲流河“二元结构”沉积，岩性具河道沉积与泛滥平原沉积“砂泥间互”的特征；短期沉积旋回控制着不同沉积砂体的分布，上升半旋回中下部和下降半旋回上部河道砂体较发育；Ng₂ Ⅴ砂层组地震相分析揭示河道状、不规则圆弧状振幅或波阻抗异常体为曲流河河道沉积和点坝砂复合体，预测河道总体上呈北东—南西和近南北向展布。预测结果与钻井实测结果吻合度高，表明窄薄河道砂体地震识别结果真实、可靠。

Seismic identification of narrow and thin channel sandbodies of the second member of Guantao Formation in Matouying Uplift

Channel sandbody of the second member of Guantao Formation is narrow and thin in Matouying Uplift, which makes it difficult to identify on seismic section. A series of techniques were used, such as pre-stack time migration (PSTM), palaeogeomorphologic reconstruction, high-frequency isochronal stratigraphic division, wireline log facies analysis, channel sandbodies tracking with line drawings of seismic section, strata-bound wave impedance inversion and seismic amplitude strata slices etc. The result shows that the vertical resolution and spatial resolu-tion of seismic data are improved by reducing the grid bin from 15 m×30 m to 7.5 m×7.5 m in PSTM processing. Ng₂ is characterized by the obvious "dual structure" of meandering channel, which display the thin interbedded layers of sandstone and mudstone. The sand bodies is controlled by short-term sedimentary cycle, and develop in the lower-middle part of short-term base-level rising hemi-cycles and upper part of short-term base-level descen-ding hemi-cycle. An analysis of seismic facies in Ng₂ Ⅴ sand unit reveals that amplitude or wave impedance anomalies with channel forms, irregular arc shape show NE-SW and near NS distributed geomorphologic systems, indicating channel and point-bar complex depositions of meandering river system. The results manifest that the predicted results are consistent well with the actual drilling, and the channel distribution laws are in accordance with regional geological laws, demonstrating that seismic identification for thin channel sand body are true and reliable.