The presence of shallow gas pockets, karsts and dissolution features in proximity to faults is a common geological phenomenon in carbonate reservoirs. Such subsurface features have been known to have an impact on well planning, assessment of hydrocarbon volume in place, well management and overall development strategy. Therefore, there is a strong business case to identify and map out these features in detail for field development purposes.The presence of karstification in carbonates causes heterogeneity at various scales. In the Bul Hanine Field, several wells have experienced losses of various degrees. Mud losses at the reported depths have been correlated with the presence of karst-related features. Knowledge of the distribution and geometries of the karst geobodies in carbonates is essential for well planning and reservoir modelling. The geohazard recognition and modelling workflows described in this paper rely on the integration of available subsurface data. Evidence of karst features was characterized with 3D seismic data, core, log and production data. Using Petrel geobody mapping techniques, the karst was picked as 3D geobodies which were then extracted based on optimized clipping parameters of the various seismic attributes. This was performed after the separation of actual signal versus noise. Several sensitivities were performed in order to optimize the final result before being integrated into a geo-cellular model.An integrated geohazard workflow on the Bul Hanine Field revealed the presence of four distinct types of geohazards which were observed at various stratigraphic intervals. Various seismic characterization techniques were deployed to detect and map karst-related geobodies. These geobodies were then incorporated into a 3D geo-cellular model and their impact on volumes was assessed. A more detailed geohazard analysis was then performed along the trajectory of the planned wells minimizing operational risks.

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