The ant tracking technique has been widely used in fault interpretation. However, the reliability of the results is highly dependent on appropriately choosing signal processing method and volume attributes. In our study area, which lies in the southern Taranaki Basin, we applied Graphic Equalizer as the processing tool and the Chaos attribute before running the ant tracking algorithm. Results show that the procedure has better quality and can map both the major and minor faults more efficiently than the conventional fault interpretation procedure.

The Lower Wilcox lowstand sand deposits encased between two sequence boundaries along the Texas Gulf Coastal Plain are of good reservoir quality and usually gas productive. However, the sedimentation is sparsely scattered within such depositional environment and it is hard to predict by qualitative interpretation methods. Simultaneous inversion of elastic parameters such as P-impedance, S-impedance, and density by the integration of pre-stack data and well logs allows us to quantitatively characterize the reservoirs, and to distinguish them from the surrounding rocks. In this study, we use pre-stack simultaneous inversion of the elastic parameters for delineation of the gas reservoir in an active field with limited log availabilities. For wells that are missing sonic and density logs, we estimate the parameters using the time average equation and Gardner’s equation, respectively. The shear wave velocity estimation methods are tested and compared using measured log value. The estimation results are verified using well log correlations in adjacent wells. Rock physics analyses on wells are conducted to find the optimal elastic parameters for characterizing the gas bearing sand. We successfully delineate the reservoir using the crossplot of VP/VS versus S-Impedance values. The inversion results are quality controlled by a producing well in the reservoir zone, and probability maps of each lithology are calculated by the probability density function. Our results from the Lower Wilcox Formation indicate that simultaneous inversion based on the estimated parameters using the time average equation is feasible, and the gas bearing reservoirs can be recommended with high confidence.

The lower Wilcox turbidite lobe deposits located above the Cretaceous carbonate shelf edges in the Central Gulf Coast region of Texas are considered as prominent targets for petroleum production. Reliably interpreting lobe deposits is challenging due to their complex seismic geometries and isolated occurrences. The Paleogene Wilcox Group hosting the lobe deposits is a thick sequence, consisting of terrigenous clastic sediment deposits formed in marine and terrestrial environments. Multi-phase regression and transgression during the late Paleocene to the early Eocene complicated the local depositional structures and developed the incised canyon features. The turbidity-flow deposits, originated from canyon-margin deltas, formed lobes in the lower onlap fill of the canyon. We analyze both seismic data and well logs to determine the morphology and rock properties of the depositional facies along the canyon system. We also utilize seismic attributes to identify the shape and lateral variations of the sandy turbidite lobe deposits inside the canyon-fill sequence. Analyses of the selected attributes, including instantaneous phase, RMS amplitude, and spectral decomposition, indicate that the prograding deltaic sediments crawled over the steep canyon walls, followed by retrograding and consequential excavation of the canyon walls, resulting in an elongated funnel shaped canyon. During the process, the sand bodies were transported into the underwater distributary channels across the basin floor, and generated the turbidite lobe deposits within the lower onlapping canyon fill.

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