Warping Least-Squares Inversion for 4D-Velocity Change: Gulf of Mexico Case Study
Chang Li, Mark A. Meadows, Todd Dygert · 2017
In this study we develop a new trace-based, warping least-squares inversion method to quantify 4D velocity changes. We solve for these velocity changes in two steps: 1) dynamic warping with phase constraints to align the baseline and monitor traces; and 2) least-squares inversion for 4D velocity changes incorporating both time shifts and 4D amplitude differences (computed after trace alignment by warping). We demonstrate this new method using simple synthetic layered models. For the noise-free case, phase-constrained warping is superior to standard, amplitude-based warping by improving trace alignment, resulting in more accurate inverted velocity changes (less than 1% error). For synthetic data with 6% RMS noise, inverted velocity changes are reasonably accurate (less than 10% error). We then apply this warping least-squares workflow to a field data set from the Gulf of Mexico, which yields inverted velocity changes that are more interpretable and consistent with the dynamic reservoir model than those estimated from the traditional time-strain method. Presentation Date: Wednesday, September 27, 2017 Start Time: 2:15 PM Location: 351F Presentation Type: ORAL