Frequency Based Interpretation of Offshore Passive Electro Magnetic Survey Data

An airborne 3D high resolution magnetic and electric (EM) survey was conducted in the Norwegian Sea offshore. This survey included survey lines over the Helgeland Basin, the Nyk High area, an area with known oil seeps, as well as three benchmark lines in the oil producing Norne area and three benchmark lines east of Norne where a dry well was located. The survey data were interpreted with unconventional frequency-based algorithms. Interpretations of these data sets validated the survey system and confirmed that: 1) The 3D passive airborne system recognized areas with and without large hydrocarbon deposits, 2) Relative depth information was obtained from a parallel interpretation with geophysical data, 3) Multiple hydrocarbon bearing strata were identified, 4) Consistent survey results were found in 1200 meters of water. Data and interpretations supporting these claims will be presented. Based on these encouraging results improved economic commercial grade data collection systems and a survey data interpretation system were developed. The purpose of this development is to make it possible to optimize existing data (such as geological and seismic data) interpretations with independent EM data interpretations. Such combined interpretations not only can reduce the exploration risk but also may come in useful for basin evaluations, the evaluation of farm-in prospects, license applications and drill site optimizations.