Publications

Pre-Stack Depth Migration (PrSDM) re-processing of the West Berau 3D Ocean Bottom Cable (OBC) seismic data has been carried out to enhance the imaging of the reservoir and the overburden section. The shallow and highly karstified Faumai carbonate overburden in the West Berau area has historically been a challenge for conventional velocity model building. To address this challenge, a hybrid velocity model building workflow was applied to reconstruct an optimum and high-resolution velocity model. This workflow uses a combination of Orthorhombic Full Waveform Inversion (FWI) and ray-based tomography. Shallow, fast carbonates in the overburden limit the penetration of diving waves to ~1500 meters depth (well above the reservoir level), restricting where the Orthorhombic FWI can reliably update the velocity model. Ray-based tomography was therefore applied to update the velocity model in the deeper section that was not updated by FWI. In this paper we demonstrate that hybrid velocity model building workflow has effectively built a high-resolution velocity model and improved the seismic image quality of the complex geological structure.