Improving Exploration Success for Paleocene Vaila Stratigraphic Traps West of Shetland
Loizou, Nick, Department of Trade and Industry,
Since 1982, 48 exploration wells have been positioned on Paleocene prospects that were believed to have a significant stratigraphic component, but few have found hydrocarbons – many failing as a result of poor trap definition and overconfidence in the predictive use of amplitude anomalies. Hydrocarbon sourcing of many of the failed prospects was also poorly constrained. Few amplitude-related stratigraphic features could be tied with confidence to a viable source kitchen. The presence of a regional seal is a prerequisite ingredient for a successful Paleocene play.
Analysis of the exploration wells shows that many were located on unreliable traps. Therefore, the sound mapping of a valid trap is viewed as the key component to increasing exploration success West of Shetland. A key observation from the analysis of the wells indicates that many were not optimally positioned to test a valid stratigraphic trap. With this in mind, exploring for valid stratigraphic structures requires a great deal more care and an improved understanding of specific trap ingredients than are necessary to generate a successful structural trap.
Without doubt, many of the failed Paleocene wells would indicate a general lack of understanding of the occurrence of sandstone pinch-out plays relative to the basinal setting and regional seal. The majority of the unsuccessful wells failed to find hydrocarbons because there was no valid trap. A technique has been developed that has been utilised for correctly identifying and support more confident mapping of robust stratigraphic traps is presented that should result in an improved success rate.