Combined Waveform Inversion and Reverse Time Modeling for Microseismic Event Characterization in Complex Salt Structures
D. Köhn, D. De Nil, S.A. al Hagrey and W. Rabbel
Event name: Second EAGE Workshop on Geomechanics and Energy
Session: Poster session
Publication date: 13 October 2015
Info: Extended abstract, PDF ( 3.23Mb )
Price: € 20
Increased emission of greenhouse gases into the atmosphere lead to a strong requirement of renewable energy resources. However, they are intermittent and need buffer storage to bridge the time-gap between production and public demands. The storage of compressed gas energy in sealed underground structures like salt caverns is one approach to bridge this time gap. The early detection of possible gas leakage paths in the surrounding of caverns can be mapped by the localization of crack-induced microseismic events. One approach is based on elastic reverse-time modeling, where the recorded seismograms of a microseismic event are numerically backpropagated and the seismic wavefield focuses at the location of the event. The success of this approach depends on the used elastic background model. In case of complex salt bodies, the strong velocity contrast between salt and surrounding sediments is a major problem. Therefore, we propose a combined monitoring approach, consisting of a seismic full waveform inversion of active source reflection seismic data to accurately image the background velocity model and a subsequent reverse time modeling for microseismic event localization. The accuracy and sensitivity with respect to random noise is demonstrated using the complex SEG/EAGE BP 2004 benchmark model.