模型约束基追踪反演方法

基于反射系数奇偶分解的基追踪反演方法,补充了地震资料中所缺失的低频与高频信息,较好地提高了反演结果对地层的分辨能力。但仅仅使用稀疏约束加入的低频信息缺乏合理性,可能与工区的实际地质情况不符,需要进一步改善反演结果的横向连续性。因此,提出在基追踪反演目标函数中加入模型约束,得到模型约束的基追踪反演目标函数,并使用梯度投影稀疏重构(Gradient Projection for Sparse Reconstruction,GPSR) 算法进行求解。模型约束的加入增强了反演的稳定性,使得反演结果中的低频信息更加符合工区实际地质背景信息,并且能够改善反演结果的横向连续性。楔形模型和实际数据测试结果表明,模型约束基追踪反演方法不仅保持了基追踪反演的稀疏性,地层阻抗呈现块化,反射界面刻画清晰,而且反演方法更为稳定,反演结果的横向连续性得到了改善,从而验证了该方法的可行性。

The basis pursuit inversion (BPI) method based on the dipole decomposition of reflection coefficients compensates the low-frequency and high-frequency information lacked in the seismic data,which can well improve the identification capability of inversion results on formations.However,it might not be reasonable to add the low frequency information just by the sparse constraint,and the information might not coincide with the true geological background.Therefore,we derived the model constrained BPI objective function by putting the model constraint to the origin objective function of BPI,and utilized the gradient projection for sparse reconstruction (GPSR) algorithm to solve the problem.It would not only enhance the inversion stability and make the low frequency information contained in inversion results more consistent with the actual work area,but also improve the lateral continuity of the inversion results.The results of the wedge model and real field data testing demonstrate that the model constrained BPI method not only keep the sparsity of the inversion results and shows the impedance in blocky,which characterizes the interface more clearly and improves the reliability of the inversion and the lateral continuity of the inversion results.

国家自然科学基金石油化工联合基金重点项目(U1562215)、国家重点基础研究发展计划(973计划)项目(2013CB228604)与国家科技重大专项(2011ZX05030-004-002,2011ZX05006-002,2011ZX05009-003)联合资助。