Geostatistically modeling topographically- controlled deposition of sub-seismic scale sandstone packages within a mass transport dominated deep- water channel belt

Geostatistical modeling methods for deep-water depositional systems, which provide a framework to characterize spatial uncertainty, have generally focused on channel-levee-overbank-lobe models. However, these models do not fit all deepwater depositional settings. For example, irregular surface topography of subaqueous mass-transport-deposits (MTDs) played a primary role in controlling the deposition of sand from turbidity currents in the vicinity of the Puchkirchen field in the Molasse Basin, Upper Austria. The MTD topography created mini-basins in which sand accumulated in irregularlyshaped deposits that are not consistent with a channel-levee-overbank-lobe paradigm. These accumulations are difficult to laterally correlate using well-log data due to their variable and unpredictable shape and size. Prediction is further complicated because the sandstone bodies typical of this setting are difficult to resolve in seismic-reflection data. To overcome these challenges related to the lack of reliable interwell prediction methods, a new geostatistical modeling approach is presented. The modeling process simulates debris flow lobes followed by turbidites that fill in the accommodation on top of and between debris flow lobes. Modeling these large scale debris flow lobes is further justified by the fact they are more reliably classified with the coarse scale seismic attributes than the reservoir facies. As such, leveraging the seismic data to predict the non-reservoir events (debris flow deposits) provides a pathway to predict the locations of significant sandstone accumulations as validated by previously drilled areas.