Investigation into the applicability of AVO techniques to coal mine exploration
Limacher, Romaric Davy
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AVO (for Amplitude Versus Offset) is a seismic technology known in the oil industry for its ability to differentiate gas sands (over oil producing reservoirs) from wet sands (over non-producing reservoirs) in the Gulf of Mexico. Its applicability to a broad range of exploration fields has led to its potential application within the ADEMA (Advances in Exploration Methods and Applications) project being considered. Within the frame of this project, this PhD thesis assesses the ability of AVO to detect a difference between Mudstone and Sandstone roofs over a 6 meters thick coal seam, in the region of Daw Mill (UK). It moreover presents a modification of a triaxial cell aimed at calibrating AVO in the laboratory, and thereby improving the quality of AVO analysis in general. The analysis presented in this PhD thesis leads to the conclusion that in this region, the particular rock properties can lead to a signal difference detectable by AVO. However, analysis of seismic data confirmed that tuning effect interferes with these distinct signals, and prevents AVO technology to differentiate mudstone from sandstone roofs. Finally, this thesis proposes different technical recommendations for successfully running a test with the modified triaxial cell in future.