West Siberia Lower Cretaceous Mass Transport Deposits Reservoirs: Presence, Distribution, and Production Features

Problem of drilling and developing reservoirs in Lower Cretaceous landslide mass transport deposits (MTD) has several layers: extremely difficult geological conditions, common seismic attributes are not detailed and don’t reflect geological conditions (reservoir model and thickness is not always verified by drilling), drilling is extremely risky, only adventurously zones remained for development. Solution is in improved conceptual and detailed geological model (understanding landslides and slumps deposition within mass transport deposits, using examples from Alps to Gulf of Mexico, North Sea and Antarctic, their structure and texture, distribution of intact slump blocks and sheets of debris flow, initial environments of deposition, what caused the landslide and where it could be predicted in the same strata in the same petroleum province and how it could be foreseen across various passive margin basins around the world). In the area of interest domains with the most net-to-gross within the reservoir (up to 35–40 m thick sandstone) are related to landslide folds 300–500 m width and 4–5 km length separated from each other by non-reservoir sectors with the same geometric properties (width and length). For detailed 3D seismic data analysis eXchromaSG technology was used, that allows to make more detailed geological concept using less time comparing to other methods like spectral decomposition. It also allows to map geological bodies more detailed laterally and vertically, than common seismic attributes. The main results are risk assessment for each mass transport part, detailed geological model approved by drilling, well placement is done with maximum possible effectiveness, effective well sandstone penetration rate and maximum production rates.