The Application of Spectral Decomposition to an offshore area, North Central Gulf of Mexico
By Andrew Welshhans, University of Louisiana at Lafayette
Spectral decomposition is a geophysical technique employed in seismic data sets to more effectively highlight lateral and vertical geologic detail, and in some cases, display the potential of resolving thin beds in the reservoir not currently visible in the processed seismic data. Spectral decomposition is non-unique; therefore any geologic information obtained from well logs or synthetics is vital for an accurate interpretation of the generated time-frequency volume. As amplitudes in seismic data representing reservoirs have characteristic frequency expressions relative to geologic detail within said reservoirs, spectral decomposition provides a means to investigate each frequency pertaining to reservoirs of interest. Though the area is known for deltaic and fluvial deposits relative to the ancestral Mississippi River Delta during the Pliocene and Pleistocene, spectral decomposition has aided in improvement on resolution and better horizontal imaging of discontinuities due to changes in lithology, faulting, and depositional features. Therefore, as the seismic data are converted to the time-frequency domain, spectral decomposition may aid in the resolution of geologic detail hidden by the processed seismic data set. Through such efforts, far better interpretations of the depositional history of the area locally may be made and the location of potential hydrocarbon reservoirs may be postulated when compared to what is known of producing reservoirs.
Andrew is a graduate student at the University of Louisiana Lafayette in geology. While completing his BA at the College of Wooster, Wooster OH, Andrew interned for a small independent Petro Evaluation. While studying at UL, Andrew interned for Medco Energi, which gave him great exposure to industry data, software, and personnel. Andrew appreciates the support of professional societies, such as LGS and SWLGS, that have made his experience at UL Lafayette very rewarding. Andrew will be attending West Virginia University in the fall to begin his PhD in geology.