Author : Taylor Jerome Dahlke
Publisher :
Page : pages
File Size : 23,5 MB
Release : 2019
Category :
ISBN :
As oil and gas extraction becomes more advanced, exploration becomes increasingly focused on imaging near or under complex salt geology, which necessitates detailed velocity models with sharp interfaces. Current state-of-the-art practices include the use of Full-Waveform Inversion (FWI). However, this type of approach can result in salt body models that lack the sharp interfaces characteristic of this type of geobody. This is typically due to the computational expense of using increasingly high frequencies in the data. These interfaces can be elegantly tracked as sharp boundaries using the level sets of an implicit surface. Used in conjunction with shape optimization, one can invert for salt boundaries that fit recorded data in a FWI style objective function that is parameterized in terms of both the implicit surface and a background velocity model. While this addition of the implicit surface requires more model parameters, radial basis functions can be used to create a sparse parameterization of it, which can hasten convergence of the inversion. The implicit surface also allows for embedding information about the certainty of different salt boundary regions by means of its initialization. This information allows for intelligent guidance of the inversion based on interpreter input, which can help the inversion avoid local minima. The result of testing this inversion workflow on a 3D Gulf of Mexico dataset shows that it can be a useful tool for refining salt models, as the seismic images produced from the final model shows clearer and more consistent features below the updated salt area.