POST-STACK SEISMIC INVERSION OF "TXT" FIELD, NEW ZEALAND

Abstract

Taranaki Basin is one of the most prolific areas for oil and gas in New Zealand. This study aims to map the acoustic impedance from Tikorangi until the Basement. Then, the map will be qualitatively used to understand the distribution of porosity of the reservoir within the interval of interest. The interval of interest includes the Oligo–Miocene Tikorangi Limestone and Middle–Upper Miocene Kapuni sandstone groups. Based on the petrophysics calculation performed on TU and KH wells, the Tikorangi limestone has average porosity of 0.05 in KH well & 0.15 in TU well, and Kapuni sandstones has average porosity of 0.2 in KH well & 0.3 in TU well. Then, cross plot between acoustic impedance and total porosity shows that the porosity is decreasing with increasing acoustic impedance. Model Based Inversion technique is used to invert the 3D seismic data to acoustic impedance cube. The inversion reveals that the acoustic impedance is higher in Tikorangi compared to Kapuni sandstone complex. This result agrees with the cross plot result that shows Tikorangi is tighter than Kapuni sandstone groups.