Hydromechanical Frameworks for Assessing the Occurrence of Wellbore Bridging and Fracture Broaching During Blowouts

Abstract

Rigorous hydromechanical frameworks needed for modeling wellbore bridging and broaching during uncontrolled production of oil and gas are developed in this work. First, two sources of sand production are identified: borehole breakout and erosion of the producing formation. Theoretical framework for predicting the morphology of type B breakout mode is developed for the first time in this study; both fracture mechanics and shear failure theories are used in predicting the breakout geometry. Furthermore, a framework for estimating the size of caving produced during breakout (type A or B) is presented. Using asymptotic analysis of crack-boundary interactions, the state of damage around the borehole during the breakout process is determined, and the limiting buckling lengths of the resulting wing-cracks are predicted based on plate buckling theory. Third, a three-phase erosion kinetic equations, coupled with an erosion constitutive law, which is based on virtual power principle, are used in modeling radial and axial erosion in the reservoir and along the wellbore respectively. The proposed erosion constitutive law identifies the limitation of the pressure-gradient phenomenological model, which is currently being used. For a rigorous investigation into the self-killing of the well, a thermodynamically multiphase field model is developed for the gas-liquid-solid flow. The model, which is the combination of Navier-Stokes and Cahn-Hilliard type equations, incorporates the hydrodynamic interactions among the different species of the mixture. Lastly, this work considers a faster means for estimating fracture propagation in heterogeneous media (layered or naturally fractured) in the event the well is shut-in.