ISSN 1004-4140
CN 11-3017/P

基于反射系数占比的合成地震记录定量标定方法

Quantitative strata calibration method based on the reflection coefficient proportions

  • 摘要: 层位标定是层位解释和储层分析的基础,目前常用的标定方法将地层界面与波峰、波谷等进行比对,注重地层界面的时深关系,将地层界面与特定的波峰、波谷或者过零点相关联,不能反映地层横向变化,误差大,无法满足精细解释的需求。本文提出了一种反射系数占比计算方法,在合成地震记录标定的基础上,根据测井声波时差曲线和密度曲线,计算出地层界面反射系数序列,进而根据地震子波计算各反射系数对指定的波峰或波谷的振幅贡献占比,建立地震波形与反射系数组成和振幅占比的定量关系。通过对该定量关系的分析,建立地层界面与井旁地震道波峰、波谷之间的对应关系,将地震数据的目标层位同相轴与其贡献占比最大的反射界面进行对应,从而确定地层分界面对应的敏感相位,选择敏感相位能够更加准确地对目标层位进行横向追踪和岩性对比分析。将该方法应用于胜利油田胜坨探区沙三下1砂组的追踪,提高了砂体解释的精度,将钻井吻合率由75%提高到92%,表明该方法在开发地震解释中具有广泛的应用前途。

     

    Abstract: Strata calibration is the foundation of stratigraphic interpretation and reservoir analysis. Current used calibration methods qualitatively compare geological interfaces with wave peaks, troughs, and other features, thus emphasizing the depth-time relationship of geological interfaces. These methods associate geological interfaces with specific wave peaks, troughs, or zero-crossing points but fail to reflect lateral changes in stratigraphy. This results in significant errors and insufficient interpretation. The present study proposes a method for calculating the contribution ratio of the reflection coefficients. Based on the calibration of the synthetic seismic records, the reflection coefficient sequence of the geological interfaces was computed using sonic travel time and density curves from well logging. Subsequently, the contribution ratio of each reflection coefficient to the specified wave peaks or troughs was calculated based on the seismic waveforms. This established a quantitative relationship between the seismic waveforms and the composition of the reflection coefficients and their amplitude contributions. Through the analysis of this quantitative relationship, a correspondence between geological interfaces and wave peaks or troughs with well seismic traces was established. The target stratigraphic level in the seismic data was then correlated with the reflection interface that had the maximum contribution ratio to determine the sensitive phase corresponding to the stratigraphic boundary interface. By selecting the sensitive phase, it was possible to track and analyze the lateral variations in the target stratigraphic level and lithology more accurately. The application of this method to the Shasan Lower Sandstone of the Shengtuo exploration area in the Shengli Oilfield improved the accuracy of sandbody interpretation, increasing the drilling matching rates from 75% to 92%. This indicates the broad potential applicability of the proposed method for the seismic interpretation of reservoir development.

     

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