CSEM as a tool for better exploration decisions: Case studies from the Barents Sea, Norwegian Continental Shelf

Abstract

After more than 30 years of exploration and more than 100 wells drilled in the Barents Sea, only one field is in production and one is under development. However, recent discoveries made over the last three years have heightened the interest for exploration in the region. Nevertheless, the industry is still facing major challenges in finding commercial volumes of hydrocarbons, despite the fact that numerous wells have encountered shows or minor amounts of gas and oil, proving a working hydrocarbon system in large parts of the area. Since 2008, 3D controlled-source electromagnetic (CSEM) data have been acquired in the Barents Sea, providing additional geophysical information in the last three licensing rounds. In this paper, we showed how CSEM data can help the industry make better decisions in various stages of exploration. CSEM data, being sensitive to hydrocarbon saturation and volume, have the potential to reduce the risk of exploration failures of a prospect by influencing the chance of success and the expected size and volume. To illustrate this, we showed three case examples. (1) How CSEM can support certain play models, and hence, give valuable information in a license application phase as well as in drilling decisions. (2) How CSEM can support decisions to apply or not apply for certain blocks in a licensing round. (3) How CSEM can help prospect ranking and drill-or-drop decisions. All these three cases demonstrate the power of using CSEM as a complementary tool together with seismic data and other geologic information. This paper argues that CSEM data could have provided a correct prediction for all of the wells drilled in the Barents Sea where 3D CSEM data are available, provided there are sufficient sensitivity and 3D inversion results. This in turn proves the value of acquiring CSEM data in addition to seismic.