Central North Sea, Quad 20, BroadSeis 3D
The first BroadSeis 3D survey was shot in shallow water over a known AVO anomaly in Quad 20 of the Central North Sea. The data were recorded as a pilot 3D study and cover an area of only 165km2 and only 7km in width, allowing only a small crossline migration aperture. The full bandwidth provides high-resolution imaging above the chalk. The improved low frequencies enhance layer and sedimentary package discrimination in the sub-BCU Upper Jurassic strata as well as in the Cretaceous above.
The BroadSeis data show excellent amplitude preservation and clear definition of the bright spot. The very shallow timeslice (below) shows clear lateral definition, and incredible detail. The improved spatial resolution may eliminate the need for a site survey.
Timeslice at 236ms, showing superb lateral resolution and sharp imaging of channel features etc.
3D Layer Differentiation
On this timeslice at 2682 ms, cutting through the base Cretaceous unconformity:
- On the BroadSeis data additional low-frequency energy helps clearly delineate deep structures
- The BroadSeis data are less noisy
- BroadSeis shows clear layer differentiation with significant dark and light layers
- On the BroadSeis data the dark events are impedance increases
- On the conventional data the balance of whites and blacks is coming from confusion caused by wavelet sidelobes
- The broader bandwidth improves correlation between traces for more reliable interpretation and auto-picking of horizons