A coupled thermo and poro-elastoplasticity analysis of stress distribution in bottom-hole rocks during drilling

Key words:  thermo and poro-elastoplasticity  bottom-hole rock stress  fully coupled  numerical solution  fragmentation mechanism

Abstract:

The stress distribution in bottom-hole rocks plays a key role on drilling efficiency. In this study, a fully coupled numerical simulation model was established, and the effects of overburden pressure, horizontal in-situ stresses, drilling fluid pressure, pore pressure and temperature on the stress distribution in bottom-hole rocks were investigated. The simulation results show that the maximum principle stress of the bottom-hole rock increases with the increasing of drilling fluid pressure, well depth and temperature difference, and it firstly increases and then decreases with the decrease of the permeability coefficient of the rock formation. In the axial direction of the well and under the bottom-hole surface, the maximum principle stress of the rocks decreases with the increase of drilling fluid pressure and well depth, while the temperature difference has little influence on it when the distance from the bottom hole surface reaches a certain value.