Seismic Amplitude Anomalies associated with Low Gas Saturation Sands A Case Study from Green Canyon Block 473 in the Gulf of Mexico

Gas saturation is suspected of being the cause of some observed seismic bright spots, resulting in drilling of several dry holes. Seismic amplitudes are sensitive indicators of the presence of gas in tertiary age sediments but poor indicators of gas saturation. As a result, a reservoir with low gas saturation is expected to have a seismic amplitude response comparable to that of a reservoir with high, commercial level, saturation. Interpretation of seismic anomalies faces a significant risk that the anomaly may be due to low gas saturation; Gross and Oliver (AAPG Bulletin, 1998) estimate that 18% of the bright spots drilled in the deepwater Gulf of Mexico are due to low gas saturation.