VSP资料局部逆时偏移方法研究  

A local reverse-time migration method of VSP data

作　　者：程磊磊[1] 

机构地区：[1]中国石油化工股份有限公司石油物探技术研究院,江苏南京211103

出　　处：《石油物探》2014年第2期149-156,共8页Geophysical Prospecting For Petroleum

摘　　要：VSP资料偏移成像处理中,速度模型精度对偏移成像(特别是逆时偏移)质量有着较大的影响。针对这一问题,研究了不受上覆复杂构造影响的VSP资料局部逆时偏移方法。方法的关键点是直达波旅行时重构技术——基于最浅到最深检波器深度范围内局部速度模型和拾取的直达波初至时间重构出直达波的旅行时场。利用重构的直达波旅行时场,进行基于激发时间成像条件的逆时偏移成像。VSP资料局部逆时偏移成像更靠近目标层,可同时避开最浅检波器之上构造的影响和炮点静校正问题,从而在直达波旅行时可重构的区域内取得更高的VSP成像质量和成像效率。理论模型和实际数据试验结果表明,即使在速度模型不太准确的情况下,该方法依然能够取得比传统VSP逆时偏移更优的成像质量。During the migration of VSP data, the accuracy of velocity model has influence on the quality of migration seismic images （especially reverse-time migration）. Aiming at this problem, a local reverse-time migration method of VSP data,which is free of the impact of overlying complex structure, is studied. A key component of the method is direct-wave traveltime reconstruction technique that uses first arrival of VSP direct-wave through a local velocity model to reconstruct the direct-wave traveltime field in the range of the downhole geophone cover- age. The reconstructed traveltime field serves for reverse：time migration based on the excitation-time imaging condition. A local reverse-time migration of VSP data could get closer to the imaging target and avoids the interference of the structure upon the shallowest geophones and shoot-side statics correction. It can he more efficient and obtain higher imaging accuracy in the local region that direct-wave traveltime could reconstruct. Numerical simulation and practical experiments demonstrate this method can get image of better quality than the one of conventional VSP reverse-time migration, even if the velocity model is inaccurate.

关 键 词：VSP资料 旅行时重构 局部逆时偏移 激发时间成像条件 

分 类 号：P631.4[天文地球—地质矿产勘探]