Evaluation Of A New Method For Predicting P-Wave Sonic Data, Timor Sea.
Honours Degree, 1999
University of South Australia
Sonic log data provide important information regarding lithology, porosity, pore fluid and seismic response. Acquisition of borehole acoustic data can be affected by poor signal propagation within the formation and by borehole-associated difficulties. There is considerable commercial interest in overcoming these acquisition problems.
Previous compressional wave modelling has been generally limited to reservoir lithologies, where detailed supporting petrophysical data are available. Wiltshire Geological Services (WGS) are developing a new approach to modelling with a theoretical basis, combining compaction theory, elastic wave theory and standard petrophysical analytical procedures. The WGS method is aimed at producing synthetic sonic logs in non-reservoir sequences, where detailed petrophysical data may not exist.
The method was evaluated using data from the Timor Sea area, on a well, sub-basin and regional scale. Results show that the method can be used with confidence to improve the quality of sonic data in a single well, where resistivity and measured sonic data exist. However, key parameters were found not to correlate between wells due to lithological variations. Therefore the WGS method cannot be used for lateral prediction of compressional velocities.
The current WGS program which implements the method should be modified to include the generation of synthetic seismograms from the synthetic sonic data, and their comparison with the actual seismic data. This ability, combined with further testing is necessary to fully evaluate the potential of the WGS method.