| 3D seismic imaging is considered as one of the key investigation and monitoring techniques
in the frame of CO2 underground storage. The knowledge about the geometry and the
structure of the reservoir including its fault inventory is a prerequisite for a reliable
assessment of storage capacity and safety. The recent development of advanced seismic
imaging and inversion techniques directly suggests their exploitation in order to achieve these
aims.
We present one of these developments, 3D Fresnel-Volume-Migration (FVM). This
technique is an extension of Kirchhoff-Prestack-Depth-Migration (KPSDM) and restricts
the smearing of the wavefield along two-way-traveltime isochrons to the actual
reflection/diffraction point using the concept of Fresnel volumes. The necessary
information to perform this restriction is the emergence angle at the receiver, which
is obtained from local slowness estimates using slant-stack or cross-correlation
techniques.
The method has been applied to the 3D SEG/EAGE salt model data set as well as a real
3D seismic data set from a potential CO2 storage site. The results show that FVM yields
images of superior quality compared to KPSDM, both in terms of resolution as well as
the suppression of artefacts. Therefore the quality of the resulting FVM images
provide an excellent basis for further studies with respect to reservoir assessment and
monitoring. |