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Investigation Up-scaled Petrophysical Measurements Using Several Micro-Level Field-Of-View (FOV) Petrographic Images on Kapuni Group in Maui Sub-basin, Taranaki Basin, New Zealand


This paper presents the results of pore level micro-analyses and characterization of the Kapuni Group sandstone reservoir in the Taranaki Basin, New Zealand. In Well Maui-7, three rock fragments of the Mangahewa Formation, situated at depths of 2736 m, 2796 m, and 2897 m, are selected for analysis. In addition, two rock fragments of the Kaimiro Formation, situated at depths of 3011 m and 3028 m, are analyzed. After sample preparation, various petrographic images are captured with a thin-section microscope at different depths of magnification. The images are then processed to study the pore networks in the space domain between a lower bound of 50 µm and an upper bound of 4 mm. Then, petrophysical parameters such as porosity, permeability, and MHR are measured at their native selected spaces (Al-Bazzaz and Al-Mehanna, 2007). The well logs, including density, neutron, resistivity, GR, and SP, are analyzed to calculate the porosity and permeability logs. Neural network processing is conducted by combining the morphological pore sample and well log analyses for the training of the computer. Using the consistent data measured and delineated from different field-of-view (FOV), up-scaling porosity, matrix permeability, MHR, and grain-size at micro-levels are investigated effectively. The petrophysical parameters obtained from up-scaling FOV scale sizes are utilized to develop a simple statistical model. The sample size scale to be measured includes 600X-FOV, which is adequate for recognizing features at 50 µm-scale size, then gradually escalates to 450X-FOV for recognizing features at 100 µm-scale size, 300X-FOV for features at 200 µm-scale size, 100X-FOV for features at 500 µm-scale size, and finally, 40X-FOV for features at 2 mm-scale size.