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Producing Pore Pressure Profiles Based on Theoretical Models in Un-drilled Deep-water Frontier Basins

Abstract

World-wide, prospectivity has been proven in the deep-water and discoveries made. Examples include Gulf of Mexico, West Africa and Voring Basin of Mid-Norway. A frequent problem remains however, that is, these new plays have little if any well calibration therefore making assessment of risk on all levels, problematic. Further complicating the risking is that is some areas such as the Levantine Basin both sub-salt and deep-water are combined but where there is now proven (sub-salt) reservoir sands within the Miocene strata. Once a prospect has been identified in the deep-water, the next stage is to de-risk this. One of the key components of this process is to use knowledge of the pressure regime to determine the drilling window(the fracture pressure minus the pore pressure), if this is too narrow then potentially a prospect is too risky/expensive to drill. Without any well calibration to estimate the likely pressure regime, this process becomes very difficult and/or inaccurate. To help reduce the risk in unexplored environments we present in this paper a proven approach that can be adopted to model pore pressure in Tertiary deep-water settings, featuring Labrador, as the main case study area featured but aslo discussing other global examples, from basins such as the Levantine Basin as well as in Mauritania, Ghana and Cameroon. This theoretical or “geological modelling” approach can then be used to sense-check any pore pressure interpretation from seismic velocity. This approach also can be used to predict the likely sub-salt pressure in un-drained reservoirs; lateral transfer and drainage effects can then be taken into consideration.