Advancing seismic inversion in practice

地震图像在揭示地壳中经济资源的位置和特征方面的能力是无与伦比的。没有其他技术可以提供地震图像的体积覆盖和空间分辨率，地震图像的信息含量在其50年的使用寿命中急剧增加。今天，用于创建此类图像的计算机方法正在从标准方法（SM）过渡到更现代的全波形反演（FWI），该方法结合了物理理论和实践经验的演变，更牢固地植根于现代数学物理。由于各种困难，包括地震数据中低频含量不足、未知的地震波形、不完全理解的物理特性以及所需的极端计算量，阻碍了FWI的广泛应用。然而，这些困难并不是新的，在SM中已经通过各种实际的方式解决了。这项研究将通过尽可能地结合SM的实际方面和必要的新发展来解决当前FWI的障碍。FWI寻求一种地球模型，当用于模拟时，可以复制观测到的地震数据。相比之下，SM寻求的是与现有井眼测量的测井曲线相匹配的地球模型。FWI不约束地球模型来匹配井信息，而SM也不试图匹配观测到的地震数据。测井曲线对于提供低频信息和确定地震波形至关重要。将数据匹配纳入到SM中，或将井眼匹配纳入到FWI中，都需要收敛到一个通用的算法。该研究项目将开发具体的方法，将测井信息整合到FWI中，同时保留FWI的其他方面，如匹配观测数据。这项研究的第二个方面是研究记录较低地震频率的方法，并成功地将它们处理成可行的图像。这些努力如果成功，将大大增加从地震图像中获得的信息。确保信息与观测到的地震数据和可用的测井数据一致，也可以减少不确定性。

Seismic images are unrivaled in their ability to reveal the location and identity of economic resources in the earth's crust. No other technology can provide the volumetric coverage and the spatial resolution of a seismic image, and the information content of seismic images has increased dramatically over their 50 year lifespan. Today, the computer methods used to create such images are transitioning from a standard methodology (SM), which incorporates an evolved blend of physical theory and practical experience, to the more modern full-waveform inversion (FWI), which is more firmly rooted in modern mathematical physics. Widespread use of FWI is hindered due to a variety of difficulties including insufficient low-frequency content in seismic data, the unknown seismic waveform, incompletely understood physics, and the extreme computational effort required. However, these difficulties are not new and have been addressed in SM in a variety of practical ways. This research will address the current roadblocks to FWI by incorporating the practical aspects of SM where possible and by new developments where required. FWI seeks an earth model which, when used in a simulation, can replicate the observed seismic data. In contrast, SM seeks an earth model that matches well logs measured in available boreholes. FWI does not constrain the earth model to match well information, and SM does not try to match the observed seismic data. In SM well logs are essential to both provide the low-frequency information and to determine the seismic waveform. Incorporation of data matching into SM or putting well matching into FWI should converge to a common algorithm. This research program will develop specific methods to incorporate well log information into FWI while retaining other aspects of FWI such as matching the observed data. A second aspect of this research will investigate methods to record lower seismic frequencies and to successfully process them into a viable image. These efforts, if successful, could significantly increase the information that can be derived from seismic images. Ensuring that the information is consistent with both the observed seismic data and available well logs should also reduce uncertainty.