倾角共反射面叠加技术在低信噪比地震数据处理中的应用

Application of the Dip Angel Common Reflection Surface Stack in 3D Low S/N Area Seismic Data Processing

随着南海东部勘探进程的推进,中深层地层(珠江组到基底)成为勘探评价的主要目的层,其勘探程度决定了南海东部储量的规模。但是由于海上各种干扰因素的存在,影响到中深层地质成像的品质,制约了南海东部下一步勘探进程,提高中深层成像品质是当前南海东部亟需解决的问题。常规共中心点叠加理论是基于水平层状介质的假设前提,有一定的局限性。倾角共反射面叠加方法对地层倾角不做限定假设,地下反射面可以是任意的角度,相较于共中心点叠加理论而言更接近实际地质情况;倾角共反射面叠加技术在共反射点及其附近第一菲涅尔带内全部反射波的叠加,因此形成超级覆盖次数,能够显著提高信噪比。经过前期理论研究、资料试验及在南海东部深水区的应用,证实倾角共反射面叠加技术能够有效改善该区中深层地震资料信噪比、适用于复杂地层地质条件,能极大地提高地震资料的可解释性。相信该理论的进一步应用将有助于指导南海东部深水区的勘探、提高勘探成功率及勘探储量规模。

With the development of seismic survey in the South China Sea,the medium and deep layer is becoming the main survey target,mainly including the Zhujiang Group and basement,and the degree of exploration of them determines the reserve volume of Eastern South China Sea.Some kinds of interference factors affect the imaging quality of the medium and deep seismic data and survey of the South China Sea. Then the most important and urgent problem is how to improve the imaging quality.Normal CMP stack theory is based on the horizontal layer.However,the premise of the dip angle common reflection surface stack method is related not with the dip angle closely,subsurface reflectors can be any angle closer to the actual geological conditions compared to the CMP stack theory.This stack method stacks the entire reflection wave in CMP and in Fresnel zone,and then forms the super-coverage and improves the S/N obviously. After the pre-theoretical research,data test and the application,this method is confirmed to improves S/N of the seismic data and fits the complex formation geological conditions and the solubility of the data can also be improved.The further application of the method could guide the survey and improve the success rate and the scale of reserves in South China Sea.