A geophysical analysis was carried out to delineate and characterize the Mid-Miocene Moki sandstone reservoir in the Taranaki basin, offshore New Zealand. The study is an effort to use the new 3D seismic from the Parahaki survey to answer some concerns of an earlier 2D seismic line that drilled a dry hole.

Well log curves were used to identify two sands within the Moki package (Moki-1 and Moki-2). Amplitude Variation with Offset (AVO) forward modeling was done to evaluate the seismic response of the Moki-1 and Moki-2 sands. The modeling results indicate that the Moki-1 sand exhibits a Class III AVO response, while the result of the Moki-2 show a class 2/2P AVO response. The Far times Far minus Near (Far*(Far- Near) AVO attribute was employed to discriminate hydrocarbon from the background geology. This attribute was applied because gathers were available only over a subset of the survey and not the entire survey area. Intercept/gradient crossplot of gathers close to the well location falls in quadrant IV and shows a wet sandstone background trend, which is consistent with the modeled response.

The results from the analysis underscore the application of fluid substitution and AVO synthetic modeling in reservoir seismic studies.