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在对准噶尔盆地腹部石南21井区岩性地层油气藏研究中,将层序地层学的研究成果与地球物理中的速度分析相结合,以高精度层序地层格架为指导,对层序地层格架内的地层进行速度研究,目的在于预测出储层内部有利砂岩发育区及储层埋深,为井位论证提供重要的基础资料.首先以岩心资料、测井资料和地球化学资料为基础,确定层序界面识别标志,通过单井相划分、合成地震记录制作,在地震剖面上识别层序界面,通过层序对比和追踪,建立起研究区等时地层格架,并以此作为速度研究的模型层位,利用模型迭代层速度反演法,有针对性地进行层序地层格架内部的层速度分布规律研究.结果表明,研究目标层序白垩系清水河组(CX0-CX3)的层速度分布规律是:南及东南部砂体发育区地层速度高,北部泥岩相对发育区地层速度低,速度的高低反映了砂岩含量的多少;速度图上高速区和低速区的平面分布形态,与属性图的平面分布范围和形态基本吻合,振幅属性图上的异常体是高速异常体,速度与振幅类地震属性在反映储层非均质性和砂体横向变化方面是相互印证、相互补充的.此外,在层序格架下的层速度反演基础上得到的目标层序CX3界面的平均速度图,其系统误差和随机噪音的影响小,时深转换所得CX3界面构造图等值线走势合理,即使井资料较少,也能得到形态正确精度较高的构造图.模拟勘探评价5个阶段的误差分析表明,钻前预测误差不超过0.33%,有效降低了岩性地层油气藏勘探的深度设计误差和风险.
In the study of lithologic stratigraphic reservoirs in Shekami 21 area in the belly of Junggar Basin, combining the research results of sequence stratigraphy and the velocity analysis in geophysics, taking the high-precision sequence stratigraphic framework as the guide, The stratigraphic velocity in the stratigraphic framework is studied in order to predict the favorable sandstone development zone and reservoir depth in the reservoir and provide important basic data for the well location demonstration.First, the core data, logging data and geochemical data are Based on which the identification of sequence boundaries is determined. Through single-well phase division and synthetic seismogram production, the sequence boundaries are identified on the seismic profiles. By sequence comparison and tracking, the isochronal stratigraphic framework is established and used as Velocity model of the study area, the layer velocity distribution in the sequence stratigraphic framework was studied in detail by using model iterative layer velocity inversion method.The results show that the study sequence of the target sequence Cretaceous Qingshuihe Formation (CX0-CX3 ) Layer velocity distribution is: South and southeastern sand body development zone stratigraphic velocity is high, the northern mudstone relative development zone stratigraphic velocity is low, the speed of the level reflects the sandstone content; speed map on the high-speed The distribution patterns of the plane and the low velocity are consistent with the plane distribution and shape of the attribute map. The anomaly bodies on the amplitude attribute map are high-speed anomalies. The seismic attributes of velocity and amplitude are important in reflecting the heterogeneity of the reservoir and the sand body Lateral changes are mutually proofed and complement each other.In addition, the average velocity of the CX3 interface in the target sequence obtained on the basis of the inversion of the layer velocity under the sequence framework shows that the systematic errors and the random noise have little influence on the time depth The contours of the constructed CX3 interface of the conversion result in a reasonable trend, and even if the well data are few, the structure diagram with the higher accuracy and accuracy can be obtained.The error analysis of the five stages of the simulation exploration evaluation shows that the prediction error before drilling does not exceed 0.33% Effectively reducing the depth of design errors and risks in the exploration of lithologic stratigraphic reservoirs.