PARIS – CGG’s Nebula 3D Phase I survey offshore southern Brazil is nearing completion and acquisition will soon start on Phase II.
The long-offset BroadSeis survey is over the Campos and Santos basins. Phase I covers around 17,700 sq km (6,834 sq mi) on the southeastern side of the survey area, and is said to provide 3D data coverage for the first time.
Phase II will cover roughly 10,000 sq km (3,861 sq mi) on the northern side of the survey area with underlying broadband datasets providing input for dual-azimuth imaging.
The Nebula Phase II dual-azimuth data should better illuminate presalt events, CGG claimed, addressing challenges posed by thick volcanic layers.
The company’s Subsurface Imaging Center in Rio de Janeiro will apply techniques including Interbed Multiple Attenuation and proprietary time-lag FWI to improve the velocity model and deliver clearer and more focused subsurface images of the presalt area.
Shearwater’s Oceanic Sirius will likely start Phase II acquisition in early December. CGG expects to issue fast-track results in late-2021 followed by final products in 1Q 2022: these will include a TTI Kirchhoff PSDM, a TTI RTM 45Hz, and a LSRTM 45Hz.