Use of CSEM data to aid a revised interpretation from the Norwegian Sea

In the 2009 licensing round for predefined areas on the Norwegian Continental Shelf, three oil companies were awarded stakes in licence PL 559 in the Norwegian Sea. An interesting aspect of this award is that the area had previously been derisked by another oil company using, among other data types, controlled source electromagnetic (CSEM) data. This led to the drilling of a dry well and subsequent relinquishment of the area. The negative result was perceived as a failure of the CSEM technology in terms of being a false positive. However, a preliminary revised interpretation of the area provided an alternative explanation for the dry well, suggesting that the observed EM anomaly was positioned outside the dry well location. After a successful licence application, new CSEM data were acquired. The alternative explanation was strengthened after detailed analyses of the new data provided support for the presence of hydrocarbons as the most likely explanation for the observed CSEM anomaly. The revised interpretation will be tested by the drilling of an exploration well during the autumn of 2011, and the results will be important in order to better understand the potential of CSEM technology for hydrocarbon exploration.