High-resolution seismic imaging of shallow karstified carbonate overburden offshore Indonesia

Heavily faulted and karstified carbonate overburden poses potential geohazards for well drilling in West Papua, offshore Indonesia. Hence, high-resolution seismic images that capture geological details, such as karstified faults and small-scale caves within the carbonate, are highly desirable. In this study, two aspects play a pivotal role. First is the velocity model, which can capture velocity contrasts that are highly spatially varying within the carbonate. Second, considering the shallow nature of the targeted carbonate layer and the sampling limitation of the Ocean-Bottom Cable (OBC) acquisition, is a solution that handles the associated illumination issue. For the former, we demonstrate with Time-Lag Full-Waveform Inversion (TLFWI) that a high- resolution velocity model that conforms to geology can be obtained, which in turn generates significant uplift in the image using primary reflections. For the latter, we propose to use multiple imaging to further enhance the resolution of the structures within the carbonate. The resulting image provides new insight into the understanding of the fault and karst systems for the well drilling plan.