A review of Shallow Water Flows (SWF) and evaluation of this prob-lem by 3D seismic data in the South Caspian Basin, Iran

Shallow Water Flow (SWF) is a type of geohazard in hydrocarbon exploration in deep-water basins. This problem occurs in deep-water basins with high sedimentation rates. When the drill hits overpressured layers below the seabed, large volumes of water and sand flow along the wellbore and ultimately, loss of well integrity may occur. This is the first study to review the literature on predicting SWF predrilling from different aspects comprehensively. We also evaluate the SWF problem in the channel by using 3D seismic data in the South Caspian Basin (SCB) as an example of a deep-water basin prone to SWF geohazard. The results of the literature show that geological settings with rapid subsidence are more likely to be associated with SWF. Pleistocene low-stand sands, channels, slumps, and chaotic zones are more prone to SWF. Compaction disequilibrium, differential compaction, and hyperpressure are the mechanisms of SWF. The most important quantitative criteria for identifying SWF environments are Vp/Vs and Poisson's ratios, P-impedance (AI), and S-impedance (SI). Post-stack and pre-stack inversion, seismic stratigraphy, seismic attributes, and geopressure prediction are the most important techniques for evaluating SWF. The results of post-stack inversion including low impedance zones and AI<3150 ((m/s).(g/cc)), show SWF problem in the central and eastern parts of the buried channel in the SCB. The review findings provide a comprehensive understanding of SWF geohazard in deep-water basins. As recommended in this review, further review research should be done to stabilize shallow water flow zone during the drilling operation.