鄂尔多斯盆地中东部中深层波组特征及地质意义

鄂尔多斯盆地中东部奥陶系盐下油气勘探近年来取得重要突破，明确中深层中元古界—奥陶系的地震反射波组特征，具有重要油气勘探意义。运用最新的钻井和地震资料，在不同岩性速度分析基础上，井—震联合精细标定，明确波组横向变化特征及其地质意义。研究结果表明：1）中深层地震反射可划分为连续性较好的奥陶系与连续性较差的前奥陶系两大波系，细分为中-弱振幅、低-中频、连续性较差（Ⅰ），中-强振幅、低频、连续性较好（Ⅱ），中-弱振幅、连续性较好（Ⅲ），中-强振幅、中-高频、连续性好（Ⅳ）4类波组；2）不同岩性组合方式及厚度变化使同一地层在不同地区波组特征不同，Ⅰ类波组分布在前奥陶系，Ⅱ类波组分布在米脂区马一段，Ⅲ类波组分布于中东部马二段与马四段以及华池区马三段，Ⅳ类波组分布在米脂区马三段以及中东部马五段；3）波组横向突变及纵向接触关系揭示该区发育两大类盐滑脱褶皱及低角度削截与超覆不整合。波组特征分析为中东部中元古界—奥陶系构造演化、沉积相带展布提供参考。

The characteristics of seismic waves and its geological significance of mid-depth layers in mid-eastern Ordos Basin

In recent years, a breakthrough has been made in the Ordovician subsalt oil and gas exploration in the mid-eastern Ordos Basin. It is significance to identify the characteristics of seismic waves in the Mesoproterozoic-Ordovician. Using the latest well and seismic data to analysis lithology velocities, make fine well synthetics, and clarify the lateral variation of seismic waves and their geological significance. The results show that: 1)The middle-deep seismic reflection can be divided into two waves system-the Ordovician system with better continuity and the pre-Ordovician with poorer continuity, which can be further divided into four seismic waves: medium-weak amplitude, low-medium frequency and poor continuity (Ⅰ), medium-strong amplitude and low frequency and good continuity (Ⅱ), and medium-weak amplitude and good continuity(Ⅲ), medium-strong amplitude, medium-high frequency and good continuity(Ⅳ). 2)The seismic waves of the same layers are different in different palce due to varied lithology combination and thickness: seismic waves of type Ⅰ distributed in the pre-Ordovician, typeⅡ distribution in O1m1 in Mizhi area, type Ⅲ distributed in O1m2, O2m4 in study area, and O1m3 in Huachi area, type Ⅳ distributed in O1m3 in Mizhi area and O2m5 in study area. 3)It is divided into two types of salt slip folds and low-angle truncation and overlap unconformity by the lateral variation and longitudinal contact relationship of seismic waves. The characteristics analysis of seismic waves provides a reference for the tectonic evolution and the distribution of sedimentary facies of the Mesoproterozoic-Ordovician in the mid- eastern Ordos Basin.