利用转换横波层剥离分析技术检测裂缝

基于前人研究成果,文中详细总结了转换横波分裂层剥离分析方法的裂缝检测原理与实现过程,并以四川盆地HXC地区陆相须家河组裂缝储层为研究对象,采用转换横波分裂层剥离分析校正技术检测目的层裂缝信息,并得出以下认识:①基于转换波层剥离分析技术的裂缝检测步骤可分为上覆层各向异性分析、上覆层各向异性校正、目的层各向异性分析三步;②快慢横波分离与层剥离技术消除了横波分裂造成转换波径向分量同相轴旅行时的余弦变化,将各向异性造成的转换横波切向分量能量重新聚焦到径向分量,使叠加剖面质量大大提高,获得了合理的"消除横波分裂效应"后的径向分量与切向分量资料;③快慢横波剖面呈现明显时延,表明目的层存在由裂缝引起的明显的方位各向异性;④裂缝主要发育于研究区西南部,裂缝发育区与实钻高产气层对应,裂缝发育方位主要为近EW-NEE向,与构造应力场以及地震解释的断裂走向一致。检测结果与实际钻/测井资料相吻合,表明了方法的有效性。

Fracture detection with layer-stripping of PS-wave splitting

Based on previous researches,we summarize in this paper fracture detections with layer-stripping of PS-wave splitting,and apply layer-stripping approach of PS-wave splitting to investigate fractures in Xujiahe formation in HXC area,Sichuan Basin.The following observations are obtained:(1)Layer-stripping can be divided into three steps:upper-layer azimuthal anisotropy analysis,upper-layer azimuthal anisotropy correction and target stratum azimuthal anisotropy analysis.(2)Layer-stripping can eliminate azimuth effects of shear-splitting and get high-quality stack sections.(3)Time delays between fast wave and slow wave demonstrate the existence of azimuth anisotropy in target stratum caused by fractures.(4)Fractures mostly grow in southeast of the area with EWNEE strike.The results coincide very well with well drilling and logging data.This demonstrates the effectiveness of this method.