Turbidite lobe deposits in a canyon-fill system

Abstract

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.