Advancing seismic inversion in practice

地震图像在揭示地壳中经济资源的位置和身份方面是无与伦比的。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，并且地震图像的信息量在其50年的生命周期中急剧增加。如今，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转(FWI)，后者更牢固地植根于现代数学物理。由于地震数据中低频成分不足、未知的地震波形、对物理的不完全理解以及所需的极端计算工作等各种困难，FWI的广泛使用受到了阻碍。然而，这些困难并不新鲜，在SM中已经通过各种实际方法解决了。这项研究将在可能的情况下纳入SM的实际方面，并在需要的情况下通过新的发展来解决目前FWI的障碍。FWI寻找一种地球模型，当用于模拟时，可以复制观测到的地震数据。相比之下，SM寻求的地球模型与在可用井眼中测得的测井曲线很好地匹配。FWI不限制地球模型匹配良好的信息，SM也不尝试匹配观测到的地震数据。在SM测井中，测井既要提供低频信息，又要确定地震波形。将数据匹配合并到SM中或将良好匹配合并到FWI中，应收敛到一个通用算法。这项研究计划将开发特定的方法，将测井信息合并到FWI中，同时保留FWI的其他方面，如与观测数据匹配。这项研究的第二个方面将研究记录较低地震频率并成功地将其处理成可行图像的方法。如果这些努力取得成功，可能会极大地增加从地震图像中提取的信息。确保信息与观测到的地震数据和可用的测井记录保持一致，也应该减少不确定性。

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.