Joint interpretation of high-resolution velocity and resistivity models from the Barents Sea

Abstract

To realize the full potential of a geophysical data set, and resolve interpretation ambiguities, the data must be integrated with other geological and complementary geophysical data. Seismic velocity and electrical resistivity are rock properties that both depend on lithology and fluid content: we show that valuable insight can be gained by integrated interpretation of high-resolution velocity and resistivity models produced by inversion and imaging of broadband dual-sensor (GeoStreamer) and Towed Streamer EM data respectively. Broadband dual-sensor seismic data enables high-resolution velocity model building and depth imaging using reflections, refractions and sea-surface multiples. As a result of advances in algorithms, workflows and high performance computing it is fast becoming routine to produce high resolution and accurate velocity models for large-scale 3D broadband dual-sensor data-sets as part of the depth imaging workflow. Thus seismic velocity is a rock property that can now be determined with sufficient resolution and precision to be of use to an interpreter in an exploration setting, before more detailed quantitative interpretation studies are undertaken. Marine Controlled Source EM (CSEM) data has been used extensively to improve the chance of success in the search for hydrocarbons given that accumulations of oil and gas can be characterized by increased resistivity. CSEM data have been used mostly to de-risk prospects. By using a Towed Streamer EM system it is possible to acquire CSEM data efficiently to determine the sub-surface resistivity reliably at both regional and prospect scales.