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Imaging of Ultra-long-term Temporal Change of Reservoir(s) by Accurate Seismic Source(s) and Multi-receivers
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, EAGE Workshop on Permanent Reservoir Monitoring (PRM) - Using Seismic Data 2011, Feb 2011, cp-220-00015
- ISBN: 978-94-6282-063-0
Abstract
The seismic ACROSS (Accurately Controlled and Routinely Operated Signal System) is a very stable and semi-permanent seismic source developed in Japan. Six units are in nearly continuous operation in Japan and one has been continuously operated since 2004. In order to examine the possibility of continuous imaging of reservoir characteristics change, we carried out simulation using single ACROSS and multi-geophones. We assumed 20% velocity changes in reservoirs. We used rectangular shape reservoirs such as 1) 500 m-wide and 50 m- thick, and 2) 50 m-wide and 10 m-thick located at 1 km-depth. We included the velocity change in shallow sedimentary layer. We can synthesize any directional single forces simulating seismic ACROSS. By use of synthesized full-wave seismograms, the back propagation can generate P, S and P-S phases. If velocity change of the sedimentary layer is < 0.1%, we can clearly obtain the rectangular shape for the reservoirs using before and after change of characteristics. However, the extent of knowledge on velocity structure and large velocity change at the surface strongly affect to the results. Use of a vertical geophone array can reduce the effect of surface velocity change. We will test the method in Japan and Saudi Arabia.