Seismic Interpretation During Well Planning, Drilling, and Production of Complex Carbonate Reservoirs of the Siberian Platform

Summary The seismo-geological analysis while drilling horizontal wells and side-tracks was developed and successfully deployed on one of the super-giant oil fields of the Siberian Platform. Reservoir rocks of faulted and fractured Precambrian carbonates were influenced by multiple episodes of tectonic activity, subsequent erosion and deep burial, complicated by intensive diagenetic processes, involving wide spectrum of different processes from development of giant karst zones to fine-scale leaching and stilolitization. During pre-drilling stage a large number of seismic attributes were analyzed to identify and interpret all kinds of seismic anomalies, which run across planned well trajectories. These anomalies are often interpreted as faults, fracture and karst zones, leaching intervals, etc. During drilling stage such zones are often confirmed by lost circulation, drill bit drops, LWD logs anomalies and other events. During production stage these disintegration zones are on one hand considered as sweet spot areas in terms of reservoir properties and hydrocarbon saturation and production, but on the other hand have increased risks of water and gas breakthrough. Therefore, good understanding and spatial mapping of such anomalous zones in carbonate reservoirs by 3D seismic methods are critically important for successful well drilling as well as for overall decrease of field development costs.