三维自适应斜井井间地震高斯束正演数值模拟

Adaptive Gaussian beam forward modeling of crosswell seismic in 3D deviated well

井间地震勘探中多为斜井或水平井,传统的射线追踪及波动方程正演方法在面对实际井间地震勘探问题时其计算精度和效率均不能满足要求.高斯射线束方法综合了射线追踪法和波动方程法的优点,不仅消除了波场的奇异性区域且有效地反映了地震波场能量的变化特征.三维斜井井间地震勘探时,应用高斯束法合成地震记录过程中存在检波点不共面的问题,此时构建一个合适的检波点平面进行高斯束合成地震记录就比较困难.基于此,本文提出一种基于炮点与检波点相对位置关系的自适应构建检波点平面的方法来解决三维斜井井间地震非共面检波点高斯束合成地震记录问题.首先介绍了检波点平面自适应构建的原理和三维井间地震高斯束合成地震记录的方法,最后,不同地震地质模型及实际资料试算的结果均验证了该方法可以很好的保留波场特征且波场分离效果良好,能够有效解决三维非共面斜井及复杂构造的井间地震正演问题,为后续的井间地震数据处理提供了准确依据.

Most wells are deviated or horizontal in crosswell seismic exploration.Ray tracing and wave equation forward modeling methods have bad performance in computational accuracy and efficiency when facing actual crosswell exploration.Gaussian beam combines the advantages of ray tracing and wave equation method.It not only eliminates the singularity region of wave field,but also effectively reflects the variation of energy of seismic wave field.The receiver points are not in the same plane when synthesizing seismic record by Gaussian beam method in deviated 3 D crosswell seismic exploration.So it is difficult to construct an appropriate receiver point plane to synthetic seismic record by Gaussian beam method.On account of this,the paper proposes a method to solve the problem of synthesizing seismic record when receiver points are not coplanar in deviated 3 D crosswell seismic,and this approach is based on the positional relationship of shot and receiver points to construct receiver points plane adaptively.Firstly,the principle of adaptive construction of receiver point plane and Gaussian beam synthetic seismic record of 3 D crosswell seismic is deduced.The results of forward modeling of different seismic geological models,different methods and field data show that this method can retain the wave field characteristics commendably and the separation of wave field is successful,thus,it can effectively solve the problem of forward modeling of crosswell seismic in 3 D non-coplanar deviated well and complex structure.It provides an accurate basis for crosswell seismic data processing.