A Successful 4D Seismic Pilot in Middle-East Carbonate Reservoir Context

This paper describes a successful 4D interpretation in a very challenging Middle East carbonate context. 4D monitoring is clearly justified by the fact that a lot of expensive wells are drilled per year and their positioning is not straight forward. Particularly the crucial fluid movement prediction (gas and water) is difficult and so is considered as the main monitoring objective.

The operator decides to acquire in 2013 a 4D pilot over approximately 25km² repeating at best the 1990’s OBC vintage acquisition design. After a cautious 4D processing step accounting for strong coherent noise and high contamination of short period multiples, relevant 4D attributes are estimated from warping and inversion, and 4D anomalies are validated and interpreted with different degrees of confidence. In particular the interpretation of the water front movement during the 4D time lapse is calibrated to well data and so can be judged as robust. This is described in the paper and proves the concept that a reliable 4D signal can be extracted over such carbonate reservoir.

A second phase of the project considering a 4D processing of different acquisition design is also alluded.