Optimization of Sparse 4D Seismic Surveys Using Seismic Full Waveform Inversion

Accurate characterization and reliable monitoring of geological reservoirs often requires extensive geophysical measurements, in particular time-lapse (4D) seismic surveys. The conventional approach to reveal the time-lapse changes is to perform comprehensive seismic surveys with high repeatability. This approach is often not economically viable for high spatio-temporal resolution of the changes and can compromise a sustainable monitoring of the reservoir. An alternative strategy for monitoring is to decrease the spatial and temporal resolution of (some of) the surveys: such surveys, referred to as sparse surveys, involve less measurements, so time and costs savings, and are therefore expected to lead to a much more sustainable monitoring solution. Careful design of sparse surveys could allow for extracting maximum information at minimum survey effort, in other words to maximize the value of information. This study has established a workflow based on the concept of value of information (VOI) to achieve cost-efficient time-lapse seismic surveying. For this purpose, we have investigated seismic full waveform inversion as a tool to optimize geophysical surveying efforts for time-lapse monitoring of producing geological reservoirs. The tool developed help the design of seismic surveys by identifying the set of acquisition parameters that implies as few measurements as possible while preserving the essential, desired, valuable information describing the evolution of the reservoir properties.