Characterization of hitherto unseen reservoirs: a case study of lithology and fluid prediction using seismic QI

摘要

After encountering a couple of gas zones in Well-1X, Idemitsu applied the in-house techniques to the 2D seismic lines across Well-1X to investigate the character of gas-bearing reservoirs in angle-stack seismic and obtained a clue to differentiate the target reservoirs from shale background. Subsequently, Idemitsu devised a specific AVO method to illuminate sandstone and carbonates reservoirs separately in the seismic data, namely 'sandstone stack' and 'carbonate stack' sections from angle gather, which resulted in revealing a series of potential reservoirs continuing intermittently below the bottom of Well-1X. Upon subsequent acquisition of 3D seismic, implementation of similar techniques provides the distributions of all the potential reservoirs on top of the detailed configuration of structures. This paper presents the representative seismic sections to demonstrate that the characters in lithology stacks, together with the extraction method of potential reservoirs using elastic-impedance-inversion, results in a Rock Physics Template (herein after, RPT). The discussion includes the rock physics properties of those reservoirs linking to why and how the properties reflect into seismic characters.