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Silje Nilsson, StatoilHydro (Norway)
Linda Beate Aasum, StatoilHydro (Norway)
Jon B. Kristensen, StatoilHydro (Norway)
Per Emil Eliassen, StatoilHydro (Norway)
Andreas Helsem, StatoilHydro (Norway)
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The undiscovered hydrocarbon resource potential has been documented for all key plays on the Norwegian Continental Shelf. The method is used to identify and calibrate "sweet spots" and will be exemplified by a case study from the Danian play in the Norwegian Sea Møre Basin.
The Møre Basin is a basin with large unexplored areas and still has exploration potential. The Danian play was proven by the Ormen Lange gas discovery in 1997. However, the Ormen Lange reservoir provenance was the Norwegian mainland and it is not considered to be genetically related to the deep marine fan system identified in the western part of the basin. In 2005, the 6302/6-1 Tulipan well was drilled as a play opener in the west and proved hydrocarbons with a westerly provenance. This well gave valuable information related to both reservoir presence, quality and hydrocarbon systems.
The total undiscovered resource potential for the Danian play includes both hypothetical resources, defined as mapped prospects, and speculative resources (leads and postulated features). Speculative resources are estimated based on play evaluation and covers the following:
•All area knowledge is summarised and illustrated by a number of key maps (e.g paleogeographical maps, present day temperature gradient maps, reservoir depth maps, HC indication map, fetch area and migration maps for potential source rocks). Additional information from special studies are included.
•Common Risk Segment Maps (CRS) were established for the Danian reservoir, seal and source. The end result is a combination of these three CRS maps for the play.
•The GeoX play assessment includes an estimate of the expected number of mapped and postulated features. A reference prospect is defined that will typically be based on information from nearby discoveries (i.e the Tulipan discovery), identified prospects and outcrop analogues. The reference prospect contains information related to area-of-closure, reservoir thickness, geometric factor, net/gross ratio, porosity, trap fill etc. In addition, both geological play risk and geological segment risk are applied in order to calculate risked resources.
The main uncertainties are related to seismic data coverage, seismic data quality (e.g. sub-basalt imaging) and density of well control. These factors strongly influence the confidence of the assessment and hence result in a wide range in the resource estimate.
The predicted reservoir distribution general controls the sweet spot distribution for the western Danian play model in the Møre Basin. These sweet spots are naturally in the vicinity of the Tulipan discovery in the western part of the basin, but undiscovered resources are also expected to be present further west, beneath the Tertiary basalts.
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