论文详情
相对于陆地资料,海上资料具有信噪比高、低频信息丰富及炮、检点耦合一致性好等优点,因此海上资料的全波形反演建模(FWI)已逐渐走向实用化。但由于全波形反演是基于波动理论的全局寻优,迭代过程中不直接修改道集,且在实际资料应用过程中往往选用道集已经拉平的初始速度场,因此常规全波形反演得到的高精度速度模型往往不能改善成像质量。为此,应用射线层析技术建立较为准确的背景速度场作为初始模型,在道集拉平速度场的基础上应用构造约束全波形反演技术,重建较为准确的地质构造和较为准确的断层位置,从而建立更加精确的速度模型。南海某油田实际资料应用结果表明,海上资料基于构造约束的全波形反演模型与实际地质构造更加吻合,复杂断层附近的速度更加准确,整体成像质量得到提高,成功解决了断层成像阴影问题。
Compared with land seismic data, marine data has the advantages of higher SNR, richer low-frequency signals, and better coupling consistency between sources and receivers; the application of full-waveform inversion (FWI) in velocity modeling for marine seismic data is gradually becoming practical.FWI is a global optimization method based on the wave equation; its iterative process does not directly modify CIGs and the initial model usually corresponds to a flat CIG in real data application.Therefore, the conventional high-accuracy velocity obtained using FWI cannot improve imaging quality.In this study, we first apply tomography to build an initial background velocity model that corresponds to a flat CIG.Then, a structure-constrained FWI is proposed to reconstruct the accurate geologic structure and fault location, thus obtaining a more precise velocity model.A test on the field data from the South China Sea showed that the inversion model was more consistent with the geological structure and the velocity near the complex fault was recovered accurately; the proposed structure-constrained FWI could help improve the imaging quality and resolve the fault shadow imaging issue.
国家重点研发计划(2017YFB0202904)资助。