This article consists of two case studies pertaining to Pliocene sediments in deep water in different blocks of the Mahanadi Basin off the east coast of India. Amplitude anomalies mapped on poststack data revealed the morphology. AVO analysis of prestack data led in both cases to interpretation that the anomalies were caused by soft layers having lower VP/VS than the VP/VS of the fluid line across the interface in intercept/gradient space. Corresponding intervals (based on the presence of high resistivity, low porosity, and low density) were interpreted to be gas-saturated sand. Drilling produced commercial quantities of gas, confirming that the low VP/VS has been caused by gas-saturated porous sands.

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