动校拉伸现象分析及其消除

Stretching phenomena and it's elimination

中国石化江汉石油管理局物探处物探研究中心,湖北潜江 433100

Geophysical Prospecting Company, Subsidiary of Jianghan Oilfield Company, SINOPEC, Qianjiang 433100, China

地下速度的变化,使各层反射界面的反射波旅行时曲线斜率产生变化,导致NMO校正中存在动校拉伸. 进而影响叠加结果。针对这一问题.①以双曲线动校公式为例,分析了动校拉伸与t₀时间、偏移距、速度及速度变化率之间的关系,并应用数学推理及地球物理概念对其进行了解释;②根据叠加速度求取过程中所采用的分时能量最大原则,给出在动校后记录的某一时间段中尽管存在动校拉伸,但最大波峰的动校位置准确的结论.并采用横向滑动寻优的方法.拾取最大波峰动校后的t₀时间;③计算动校拉伸因子.进行反拉伸校正。最后.应用理论合成记录和实际资料对上述方法进行了验证。结果表明,用上述方法处理的剖面.同相轴的连续性和资料的信噪比都得到了提高。

The variation of subcurface velocity affects reflection travel time rate of curve on every layer underground-reflected surface. Result in existing NMO stretching on NMO correct, effect on stacking. Aimed at the problem, ① example to hyperbola NMO correction formula, research relation into NMO stretching and t₀, offset distance, velocity and rate of change velocity, then interpreted with applied mathematics reasoning and geophysical conception. ② Give the conclusion exactly that NMO correction site at the maximum of wave crest by the most timesharing energy principle used in the process of request for stacking velocity. Using to lateral skidder look for better method, collection the t₀ after the maximum wave crest correction.③ Calculation the NMO stretching factor, do anti-stretching correction. Finally, the methods above are validated by theory composite trace and actual data The continuity and signal-noise ratio are improved by these methods.