Reflection Seismic Applications in Coalbed Methane Exploration – Kalahari Karoo Basin, Botswana

The historical 2D seismic data, initially acquired for gold exploration in 1980s, have been reprocessed and interpreted for the development of coalbed methane (CBM) reservoirs, a potentially important new energy source in the Kalahari Basin, Botswana. The seismic data are characterized by a seismic zero phase wavelet with the dominant peak frequency of 45 Hz, an average velocity of 3200 m/s, and wavelength of approximately 71 m. The results show a good correlation between seismic coal reflector and the borehole coal sequence at the top of Mmamabula Formation.

Interpretation of the existing 2D seismic lines demonstrates that reflection seismic method is an invaluable tool in CBM prospecting and development. This provides evidence that Mmamabula Formation is coal bed methane bearing and this information may provide guide for future CBM exploration in the area. Further to this, this gives confidence in both the geological correlation of the seismic reflectors, and the time/depth relationship of the data. The seismic sections show major faulting, suggesting that the basin may have undergone some major extensional event post coal depositional phase. This information could be factored in the future for the security of the country’s energy.