海上单道地震资料中多次波的衰减

Multiple attenuation for marine single-channel seismic data

（国土资源部广州海洋地质调查局，广东广州510075）

Guangzhou Marine Geology Survey Bureau, Guangzhou 510075, China

海洋单道地震资料中存在严重多次波，但针对单道地震资料识别和压制多次波的方法不多。通过剖面观察、自相关分析等手段将海洋地质调查单道地震资料中存在的多次波分为两大类。针对各自的特征，利用预测反褶积和模型拟合方法对它们进行了衰减试验。试验表明，预测反褶积用来衰减周期性强的短周期多次波比较有效；对于不规则的崎岖构造产生的短周期多次波，预测反褶积会有二次残留，可以使用自适应预测反褶积进行压制，但会造成数据空白。模型拟合方法适用于压制与一次波有明显区别的长周期多次波，其中参数LNC值对多次波衰减的效果有影响，值太大则难以识别多次波；值太小，会使有效波被衰减。对于多次波与一次反射差别明显（反向斜交）的情况，LNC值可以取小一些使得多次波衰减更干净;对于多次波与一次反射差别不明显（同向斜交）的情况，LNC值要取大一些，以免造成有效反射被误认为多次波而衰减掉。

Multiple is a big problem for marine single-channel seismic data processing. However, few methods can be applied to single-channel seismic data. Through section observation and autocorrelation analysis, the multiples of single-channel seismic data from marine geology survey were classified into two kinds. Predictive deconvolution method and pattern fitting method are used to attenuate the multiples. The application shows that predictive deconvolution is more effective in suppressing short period multiples with strong cyclicity. For the multiples from irregular structure, some residual multiples exist after predictive deconvolution. Self-adaptive predictive deconvolution can be adopted to suppress them, but the method may lead to the lack of data. Pattern fitting method is suitable for attenuating long travel time multiples due to its difference with primary. The LNC impacts multiple attenuation. Large value of LNC may lead to the difficulty of multiple identification and small value of LNC may attenuate the effective waves. If multiples are apparently different from primaries, a smaller LNC is suitable to suppress more multiples. But for multiples similar to primaries, a larger LNC is needed to protect primary from being attenuated.