Modelling the effects of thin beds on amplitude versus offset response using the Campbell-2 well

Abstract

Studies of Amplitude Variations with [Versus] Offset (AVO) have been used in Australia and worldwide to evaluate possible hydrocarbon prospects. This study concentrates on modelling the effects of thin beds (carbonates, shales) above and within sandstones on AVO behaviour. Forward modelling of synthetic gathers from the Campbell-2 well has confirmed that the strongly anomalous AVO response observable over the gas and oil field is due to the hydrocarbon column in the Flag Sandstone of the Barrow Group. Modelling presented here shows that a 5 m thick shale with its top 15 m below the top of the reservoir modified the AVO response of the top of the reservoir, but this response is still strongly anomalous. However, modelling a reservoir with two 5 m thick shale beds located 5 m and 15 m below the top of the reservoir modified the AVO response of the top of the reservoir to the extent that the AVO response is not significantly anomalous.