Thien Huong Phan

MSc Student

Telephone: +61 8 8303 4594

Facsimile: +61 8 8303 4345

MSc Project:

An investigation of depth conversion methods in the Cooper and Eromanga Basins.

Commenced: 2000

Supervisor: Mr Andy Mitchell

Project support: Santos Ltd

Scholarship support: AusAid

Depth conversion remains a critical issue in the exploration for and development of hydrocarbon reserves, not least in mature basins, such as the Cooper, where the remaining structural prospects are generally of very low relief. In these circumstances, errors of the order of half a percent in the depth conversion can mean the difference between a successful well and a dry hole. A major cause of depth conversion errors in these basins is the presence of carbonate cements in some of the Eromanga Basin sandstones.

The aim of the proposed project is to evaluate the accuracy of several methods of depth conversion as applied in the Cooper and Eromanga Basins. The main method to be examined is the use of apparent or pseudovelocities (twice the well depth divided by seismic two-way time). Other possibilities include the use of smoothed Dix interval velocities and cokriging of average velocities with the stacking velocity field.

The project seeks to quantify the likely depth error as a function of the method employed and the well control used in its application. In addition, analysis of each method may reveal the source(s) of error, and indicate ways in which the error could be reduced.

Ms Phan is in the early stages of the project, and is investigating the errors in the pseudovelocity method. Santos Ltd has provided a 3D seismic volume and well data over the Moomba Gas Field, which has been chosen as the study area for the project.