Integration of 1D and 3D modeling schemes to establish the Farewell Formation as a self-sourced reservoir in Kupe Field, Taranaki Basin, New Zealand


Along with conventional methods, this paper proposed a method in which 1D and 3D models are integrated to identify the self-sourced reservoir potential of the Farewell Formation in the Kupe Gas Field within the Taranaki Basin, New Zealand. Source rock characteristics were evaluated at both field and basin scales by investigating source rock maturity, type of organic matter, and hydrocarbon generation potential by rock pyrolysis, using Rock-Eval 2 and 6. The 1D thermal and burial history model established the rate of sedimentation and thermal history of the Kupe 4 well. Reservoir characterization at field-scale was determined by seismic interpretation, well log analysis, and 3D structural and petrophysical models. The sediments of the Farewell Formation contain types II–III (oil/gas prone) and type III (gas prone) and have fair-to-excellent generation potential. The oxygen and hydrogen indices ranged from 3 to 476 mg CO2/g TOC and 26 to 356 mg HC/g TOC, respectively, whereas the thermal maturity determined by vitrinite reflectance values ranged between 0.3% and 0.72%, indicating that the Farewell Formation is in immature-to-mature hydrocarbon generation stage. Thus, Farewell Formation was verified to be a good source rock. Additionally, structural interpretations demonstrated the structural complexity of an extensional and contractional regime within the reservoir package. Multiple faults indicated a good reservoir property there with a trapping mechanism as well as migration paths. A well-log-based petrophysical analysis established the presence of up to 70% hydrocarbon saturation within the pore spaces of Farewell sandstones. The 3D models confirmed that the Farewell Formation has significant sand zones and hydrocarbon-saturated zones, thereby proving its very good reservoir characteristics. It has been proved that the 1D and 3D structural schemes, integrated with geological techniques, was vital in identifying the Kupe Field as a self-sourced reservoir.

Frontiers of Earth Science