论文详情
逆时偏移的边界条件及存储需求往往相互制约,二者的选取直接影响逆时偏移的成像结果和适用条件,因此对逆时偏移边界条件和对应存储策略的研究具有重要意义。提出了一种衰减随机边界条件,在真实波场外围依次加入衰减层和随机速度层,可有效降低随机反射对真实波场的能量干扰。对波动方程逆向运算重建激发点波场,结合互相关成像条件,完成逆时偏移计算。对比分析随机边界条件、完全匹配层边界条件和衰减随机边界条件的测试结果,与随机边界条件相比,衰减随机边界条件在牺牲较少存储效率的情况下,能够获得接近吸收边界条件的偏移效果。盐丘模型和大偏移距模型算例分析结果验证了以上结论的正确性。
The boundary conditions and storage requirements of reverse time migration (RTM) are often restricted to each other.The selection of these two parameters directly affect the imaging results and application conditions of RTM.Therefore,it is very important to study the boundary conditions and corresponding storage strategies for RTM.We proposed a damped random boundary condition,in which the energy attenuation layer and the random velocity layer were added outside of the real wavefield in turn.This method could effectively reduce the energy interference from random reflection.The inverse operation of the wave equation could reconstruct the source wavefield.Combined with cross-correlation imaging conditions,we conducted the RTM calculation.The results of comparison and analysis show that,compared with the random boundary condition,at the expense of less storage efficiency,the proposed method could obtain a better migration result,and the accuracy is very close to the results obtained by the perfectly matched layer boundary condition.The correctness of the above conclusion is verified by the example of salt model and big offset model.
国家自然科学基金项目(41574117,41474118)、黑龙江省杰出青年科学基金项目(JC2016006)、大连理工大学海岸和近海工程国家重点实验室开放基金项目(LP1509)、黑龙江省自然科学基金项目(D2015011)和东北石油大学研究生创新科研项目(YJSCX2016-002NEPU)联合资助。