Unraveling the Complex Subsurface with a High-Resolution Earth Model in the Taranaki Basin, New Zealand

Summary The Taranaki Basin is located west of New Zealand’s North Island and contains most of the country’s proven oil and gas reserves. The basin has experienced a complex geological evolution with multiple phases of extensional and compressional tectonic activity. Legacy imaging efforts have struggled to overcome all of the imaging challenges that are present across the basin. These challenges include significantly varying overburden, complex extensional and compressional fault networks, and shallow gas clouds. As a result of these challenges, there are impacts on the interpretability of deeper producing reservoir intervals, but also prospective un-targeted intervals. This has resulted in the necessity to ensure that shallow intervals are imaged correctly through a detailed and targeted velocity model building strategy. This case study demonstrates the successful application of full-waveform inversion (FWI) using refraction and reflection energy, complemented by Q-FWI and common image point tomography, to deliver a high-resolution, geologically-plausible earth model that explains the seismic data and well data. The detailed earth model enabled the final Q-Kirchhoff prestack depth migration to compensate for the kinematic distortions and gas-related absorption effects observed in the survey. The results enabled better understanding and improved interpretation of the proven and unproven plays in Taranaki basin.