Seismic bright spots in the Gulf of Oman

Bright spots observed on continuous seismic profiles in the Gulf of Oman, in the northwest Indian Ocean, have been interpreted as due to gas accumulations. Features diagnostic of the presence of hydrocarbons and the corrections necessary to convert measured reflection amplitudes to interface reflection coefficients are discussed with reference to a prominent bright spot over 2 km in extent which occurs beneath the flat-lying sediments of the Gulf of Oman abyssal plain. The reflection coefficient of the upper interface of this reservoir reaches ?0.18. Detailed consideration of the measured travel times and reflection amplitudes and comparison of observed records with synthetic normal incidence seismograms constructed using realistic predictions of the source waveform suggests that the reservoir has a constant thickness of about 35 m. The gas saturation decreases laterally to zero at the margins, but it is impossible to accurately define the degree of gas saturation within the central part of the reservoir from seismic information alone.