f 4D Feasibility Study in Carbonate Field for Reservoir Management

The use of the 4D seismic method for reservoir management has been well known in the Oil Industry for a number of years. The method provides a geophysical measurement of fluid and rock property changes during the lifecycle of a producing field and allows cost effective and timely reservoir management decisions. Most of the success stories from 4D work in the past have been in clastic reservoirs where the seismic response to production is greater than in carbonates. A 4D seismic study on a carbonate field in the region has shown to be successful in imaging a GWC rise and this has led to increased confidence in the use of 4D for other carbonate fields. M4 is a newly developed carbonate gas field with oil rim that came on stream in 2002. The field is a reefal fiat top <br>carbonate built-up. It is developed with two sub-sea horizontal wells located at the top of the structural high. There is no other observation well for reservoir dynamic behavior monitoring. It is therefore critical to know the GWC movement in establishing the security of supply from this reservoir and to put in place mitigating measure as earlier as possible. A 4D seismic survey is planned for the field in 2005/2006. This feasibility study was carried out to provide support for the planned 4D seismic survey with the objective of 1) Assessing whether a 4D signal could be detected and 2) Predicting the best time for the Monitor survey. The workflow and findings of the 4D feasibility study will be outlined in the Poster.