Subsurface hazards assessment (SSHA) is an essential part of the well planning stage. Successful well execution depends on reducing geological uncertainties associated with hazards and it might prevent unexpected geological non-productive time (GNPT). Ultimately, SSHA can prevent possible catastrophic wellbore failure and loss of control in the drilling operation. The Pre-Caspian basin with its three megacomplexes has different geological hazards and requires unique drilling practices. Hazard mitigation plan can be developed both during well maturation and execution stages by acting accordingly. The approach should incorporate integrated analysis of geological, geophysical, and drilling data. Detailed SSHA and mitigation plan development are valuable constituents and basements for planning safe and cost-effective execution actions. The GNPT incurred due to insufficient recognition of geological uncertainties and underestimation of hazards can cost extra capital up to 30% of the total well execution expenditure. In addition, detailed SSHA is critical to deliver wells as designed ensuring reservoir penetration, formation evaluation and completion installation objectives are achieved fully, and future production is not compromised.

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