Abstract

This article is devoted to hydraulic fracturing justification, risks estimation and fracture optimization for ultra deep wells in regions with a complex tectonic regime, high temperature and Abnormal High Pore Pressure (AHPP) conditions, using the example of Karatobe-Burbaital well No. 101, The Caspian depression.

An approach was used to optimize well stimulation by hydraulic fracturing. Optimization is based on 1D Mechanical Earth Model and core tests results for petrophysical and mechanical rock properties. The model considers the thermal effects which influence on perforations and stress distribution around the borehole. The drilling and well development histories are used in the modeling.

Based on the geomechanical model results a complex tectonic regime has been identified involving the fracture propagation in both vertical and horizontal planes. The conducted complex analysis showed the presence of a hydrodynamic connection with the underlying water-saturated layer. Hydraulic fracture program was optimized accounting geological conditions, equipment technical limitations and multi-layer reservoir, with the risk that one fracture might be propagated into the underlying water-saturated formation. According to the stimulation program the fracture geometry was determined and starting rates were estimated. This allowed to determine the hydraulic fracture possibility and well stimulation feasibility underthese conditions.

Successful hydraulic fracturing in regions with a complex tectonic regime, high temperature and AHPP conditions requires a comprehensive optimization approach based on an accurate geomechanical model.

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