High-Resolution Full-Waveform Inversion for Structural Improvement and Prospects Delineation: a Case Study at Haugaland High

The Haugaland High, in the Norwegian North Sea, consists of a layered overburden of sub-horizontal sediments of almost 2km thick which sits on the Cretaceous Chalk. The background velocity regime of these top layers has a low vertical gradient down to the Chalk interface. This velocity behavior is particularly poorly suited for diving wave FWI and the strong multiple content present in the data does not allow an efficient tomographic update. Using all reflection and diving waves recorded in the Time-Lag FWI has allowed to provide a high-resolution velocity field, well explaining the complex velocity variation present in the overburden and easing the reservoir imaging. With the use of narrow azimuth towed streamer covering 2000km2, the velocity was updated up to 40Hz both helping structural imaging and bringing additional information to better understand the rock property of the basement over the entire region.