Three-dimensional seismic angle migration and tomography

Addendum to the project proposal from SINTEF/NTNU

This document gives some more detail about milestones, project phases, exit gates and cost control for the above mentioned project proposal.

Milestones (planned)

Project Start: 1st of July 2005

Project End: 30th of June 2009

In the following, 1 year is to be understood from the 1st of July to the 30th of June.

Cost:

The annual fee per sponsoring company is set to 500kNOK. This assumes at least 3 participating companies.

Project initiation

We would like to have feedback on this proposal within the 1st of March, 2005. A kick-off meeting will then be arranged within April 2005.

Suggested plan of project phases

-Angle migration for PP waves in 3D isotropic media

-Angle migration for PS waves in 3D isotropic media

-End of year 1

-Tomography for PP waves in 3D isotropic media

-Tomography for PS waves in 3D isotropic media

-Picking of interfaces (map migration/demigration)

-End of year 2

-Ray tracing for qP waves in 3D anisotropic media

-Angle migration for qP waves in 3D anisotropic media

-Ray tracing for qS waves in 3D anisotropic media

-End of year 3

-Angle migration for qS waves in 3D anisotropic media

-Tomography for qP and qS waves in 3D anisotropic media with constraints on interfaces(co-depthing).

-End of year 4

The final workplan will be defined on an annual basis in close cooperation with the steering committee, consisting of representatives from the participating companies.

Datasets:

The algorithms will be tested on field data. Selection of datasets will be discussed during a kickoff meeting.

Exit gates:

The main difficulties in this project will be:

  • The memory management for the 3D angle migration: Different possibilities exist if no satisfying solution can be found. First, for tomography, we don’t need to image the subsurface on a fine grid. Also, this reduces considerably the amount of required memory. Then, to obtain a full image, it is also possible to split the subsurface in different images.
  • The matching of (pieces of) interfaces in both PP and PS sections: this is required to invert for anisotropic parameters. This step might be difficult in 3D and instead of using interfaces in the migrated images for co-depthing, we might use well information for depthing both the PP and PS image volumes.
  • The ray tracing for qS waves in anisotropic media: The coupling of the qS waves in weak anisotropic media will lead to strong theoretical and practical problems. If no general anisotropic ray tracing can be developed, it is still possible to use the quasi-isotropic approximation, valid in isotropic and weak anisotropic media. This is an extension of the isotropic ray tracing.

Cost control and project administration:

Key information will be sent to the customers on a monthly basis. Meetings will be arranged to present the evolution of the project at least once a year, preferably twice a year. In case of major problems, a reorientation of this project will be redefined in agreement with the customers.

Contacts:

Mathias Alerini, Research Scientist, SINTEF, , tlf +47 73 59 13 90

Bjørn Ursin, Professor, NTNU, , tlf +47 73 59 49 78

Svend Østmo, Research Director, SINTEF, , tlf +47 73 59 11 36