Challenges of 3-D Interpretation and Seismic Reservoir Characterization in the Depth Domain
Le Stunff, Yves, Total, Pau, France
Seismic interpreters are often reluctant to work directly in the
depth domain, although benefits are numerous. These include a direct link with
geo-models for the transfer of horizons, faults or attributes and improved
communication with geologists, reservoir engineers and drillers.
The main concern is the difficulty to solve simultaneously the
problem of time-to-depth conversion and the problem of imaging, i.e. the
difficulty to find a 3D velocity model that satisfies simultaneously well data
and seismic velocities. 3D Seismic Tomography algorithms are now able to mix
well and seismic velocity information (usually through the introduction of
anisotropy). However further local refinements of the model are usually done
since depth interpreters require a highly accurate velocity model. Thus one of
the challenges is to be able to refine and update quickly 3D velocity models
and 3D seismic depth cubes without going into costly additional depth migration
steps.
Seismic
reservoir characterization in the depth domain is also in its infancy. Only
Preserved Amplitude Pre-Stack Depth Migration
algorithms are able to produce,
in theory, seismic information that can be directly used for reservoir
characterization. This technique remains however costly and other solutions
such as
migration
of seismic attributes (from time migrated data) can be a good
alternative. Examples of seismic characterization on Preserved Amplitude Depth
Migration
and of
migration
of seismic attributes will be presented. The
development of these techniques will have of course a large impact on future 4D
studies where working in depth is a key element for success.