Global 4‐D seismic inversion and time‐lapse fluid classification

Abstract

Independent inversion of base and monitor seismic surveys can yield estimates of elastic properties that are inconsistent with expected production effects. We therefore propose a global time-lapse inversion scheme, involving joint inversion of base and monitor data. All vintages and input angle stacks are combined in a single objective function, which is optimized using simulated annealing to estimate the time-variant distribution of elastic attributes that best matches all available data. The multi-vintage nature of the optimization allows us to incorporate flexible, user-defined rock physics constraints on the evolution of V p , V s and density between consecutive surveys. There are no restrictions on the number of input angle stacks or number of monitor surveys. The constrained, global inversion solution can therefore be easily updated as new data become available. We apply the global 4-D inversion with rock physics coupling to data from the Brage Field and compare results with a workflow involving separate inversions of base and monitor data. The global 4-D inversion results are combined with a time-lapse Bayesian fluid classification scheme to map production-induced fluid movements and quantify associated uncertainty.

Practical Applications of Time-lapse Seismic Data

“…Another 4D inversion approach is a global scheme in which all vintages and angle stacks are inverted simultaneously Lafet et al, 2009). Coupling can be achieved by employing rock-physics constraints and by honoring the expected production effects.…”

Seismic characterization of heavy oil reservoir during thermal production: A case study

“…Time-lapse inversion is an effective tool for reservoir characterization and fluid monitoring, and many people have done research on it (Sarkar et al, 2003;Zhang et al, 2006;Lafet et al, 2009). Different methods may work for different data.…”

4D Joint Stratigraphic Inversion of Prestack Seismic Data: Application to the CO2Storage Reservoir (Utsira Sand Formation) at Sleipner Site

“…The estimated time-scaling law is then used to jointly invert all time-lapse seismic data. Concerning inversion itself, some authors have noticed an improvement by introducing a coupling between the vintages in the seismic inversions, for example through the inversion of the amplitude differences between the baseline survey and the monitor survey (Buland and El Ouair, 2006;Sarkar et al, 2003;Lafet et al, 2009), or at least through the use of the baseline inversion result as an initial model for the monitor survey inversion (Sarkar et al, 2003). Notice that this coupling requires the preliminary time-alignment of the base and monitor seismic data before proceeding with the rest of the procedure.…”