The article describes a case history of geomechanical modeling for drilling wells in a zone with active geodynamics. Two vertical wells have been drilled in the site by the time of work performing. While drilling, there were complications connected with subsurface geology. The field is located in the Arabia-Eurasia continental collision zone. To evaluate the risks of potential horizontal well drilling, it was decided to perform an in-depth complex analysis of the well log using 1D geomechanical modeling. Analysis of drilling events has shown that work area is characterized by high probability of borehole wall collapse and fluid loss, especially in Upper Cretactous formations. The main difficulty in building 1D geomechanical models is a limited range of source data. Modeling is made on the base of taken from literature dependency reports for the calculation of stress-related properties with additional model ratio adjustments. Range of studied well log is about 3000 m. The well log is represented by interlayering of various carbonaceous and terrigenous sublayers significantly differing in the values of stress-related properties. Corresponding dependencies of longitudinal and transverse wave slowness and density recovery have been selected and justified for each interval. Stress-related properties have been calculated with consideration of lithological column for each well. Due to the absence of specialized studies concerning hydraulic fracturing of formation closure pressure, calibration of minimal horizontal stress has been made using FIT data. Calibration of minimum horizontal stress and ratios in dependencies for the calculation of stress-related properties is made in such a way that lets the final model to credibly describe drilling events and destruction intervals registered by data calipers simultaneously at all wells. Using modeling results, safe drilling windows for the estimated horizontal well path are calculated and recommendations for the following trouble-free drilling are formed. Obtained modeling results may be used in preparation of project documentation for the construction of horizontal well sat this field.
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