Merging 3D Seismic Data for IR Field Development

Abstract

Abstract The development plan of IR field, located in Murzuk basin, SW Libya was approved in August 2007. The discovery well was drilled on NC186 block in 2005. Then, it was followed by appraisal wells on both NC186 and NC115 blocks in 2006. IR field straddles blocks NC115 and NC186 that have different partners and petroleum contracts, although the same development and production operating company. The field is relatively complex due to the reservoir heterogeneity of Ordovician sandstone Mamuniyat in the area of interest. 3D seismic is one of the important datasets for selecting producer and injector locations, developing the field effectively and reducing the risk associated to drilling those development wells. No specific development 3D seismic was acquired for IR field yet. The current available 3D cube is the result of merging two exploration 3D seismic datasets: NC186-2003 and NC115-2006. This cube has been used as the basis for the interpretation during the Phase 1 of IR development plan. Up to now, several well results deviated from the prognosis in terms of reservoir top depth, thickness and quality. Those deviations are indicative of a seismic dataset not robust enough for detailed reservoir interpretation. A further investigation identified different kinds of hiccups on transit time, amplitude and phase mismatch with borehole seismic data, and the footprint of the merge boundary of 2003 and 2006 exploration 3D seismic cubes. Those identified flaws have to be addressed prior to further use of the merged 3D cube as a predictive tool for main reservoir depth, presence, lateral extension and properties. This paper will present the efforts and strategies adopted to resolve the encountered inconsistencies and artifacts, and improve the quality and reliability of the merged 3D cube. Therefore, the enhanced quality 3D cube can be used for reliable and consistent reservoir characterization to support the Phase 2 of IR development plan in year 2010.