三维转换波叠前方位各向异性校正技术

3D converted wave prestack azimuth anisotropy correction

转换波成像与常规纵波成像不同的是转换波受方位各向异性的影响更为严重,相同反射点的快、慢波时差可达到40ms,严重影响转换波成像质量和分辨率。本文以横波分裂理论为基础,提出了一种叠前方位各向异性校正技术。该技术是基于共检波点叠加的层剥离转换波方位各向异性分析方法,并在叠前共检波点道集上进行方位各向异性校正。通过该技术在喇嘛甸工区的应用,得出T2层方位各向异性的主方位在67°～84°之间,快慢波时延在10～40ms之间。经过方位各向异性校正后,径向分量能量增强,切向分量能量减弱,提高了转换波成像质量和垂向分辨率。

Converted wave imaging is affected much more seriously by the azimuth anisotropy than conventional P-wave imaging.In the same reflection point,the time-delay between fast wave and slow wave can be up to 40 ms.So the quality and resolution of converted wave imaging will be seriously damaged.According to the shear wave splitting theory,we propose a method of prestack azimuth anisotropy correction.Based on the converted wave common receiver point stack,layer stripping method is used.The method is applied in Lamadian Project.The azimuth anisotropy direction is in 67°~84°,time-delay between the fast-wave and slow-wave is in 10~40 ms by analysis in the area.After azimuth anisotropy correction,the radial component of energy is enhanced;and the transverse component of energy is attenuated.Both the quality and the vertical resolution of converted-wave imaging are improved.