最小二乘逆时偏移中黏弹性和各向异性的校正:以渤海湾地区地震数据为例

Correction of viscoelasticity and anisotropy in least-squares reverse time migration:a Bohai Bay seismic case study

地下介质中存在黏弹性和各向异性,在应用最小二乘逆时偏移时,如果没有对黏弹性和各向异性的影响进行校正,在观测数据和模拟数据的匹配过程中就会发生错误,最终使得最小二乘逆时偏移无法得到准确的成像结果.因此,本论文首先对最小二乘逆时偏移的黏弹性和各向异性进行分别校正,然后对两种影响进行同时校正.在实际资料试算部分,通过对渤海湾数据进行测试,分别采用常规声波最小二乘逆时偏移、补偿黏弹性的最小二乘逆时偏移、校正各向异性的最小二乘逆时偏移及同时校正两种性质的最小二乘逆时偏移进行比较测试,证明了在同时校正了黏弹性和各向异性影响之后,最小二乘逆时偏移得到了更高质量的成像结果,具体表现在低频噪音压制、震源效应压制、深部能量改善、分辨率提升、目的层刻画等方面都明显优于其他三种最小二乘逆时偏移的成像结果,同时也证明了同时校正黏弹性和各向异性最小二乘逆时偏移方法的正确性及在实际资料处理中的适用性.

There is viscoelasticity and anisotropy in underground media.If the effects of viscoelasticity and anisotropy are not corrected when the least-squares reverse time migration (LSRTM) is applied,imaging errors will occur in the process of matching the observed data with the synthetic data,making LSRTM impossible to obtain accurate imaging results.Therefore in this paper,the viscoelasticity and anisotropy of LSRTM are corrected separately,and then the two effects are corrected simultaneously.In the section of real data example,we use the conventional acoustic LSRTM,viscoelasticity-compensated LSRTM,anisotropy-corrected LSRTM and viscoelasticity-and-anisotropy-corrected LSRTM to test the Bohai Bay seismic data,respectively.The results verify that after correcting the effects of viscoelasticity and anisotropy,LSRTM can obtain higher quality imaging results,suggesting that the viscoelasticity-and-anisotropy-corrected LSRTM has better effect in suppressing noise,suppressing source effect,improving deep energy,improving resolution and depicting target layer than other three LSRTM methods.In addition,the correctness of the viscoelasticity-and-anisotropy-corrected LSRTM method and its applicability in practical data processing are also proved.