Abstract

Stress reorientation is an important issue for the refracturing design and candidate well design. The long term production/injection causes the stresses to reorient. The temperature differential and pressure differential induced thermal elastic stress and poroelastic stresses are the fundamental reasons for the stress to reorient. A model and numerical scheme are developed to study the effects of thermal differential and pressure differential on stress reorientation. In the model, thermal diffusion and convection is coupled with hydraulic diffusion to obtain the temperature distribution reflecting the cumulative impact. The effective poro-elastic and thermo-elastic stresses are obtained from 1-D displacement equilibrium equation in a radial system. The 3-D in-situ analytical effective stress is superimposed on the 1-D solution. By applying this methodology the 3-D deviated borehole stress model is greatly simplified. The method makes it practical to obtain the stress distribution at any given injection/production time. The thermal stress, poro-elastic stress effects on the stress reorientation are compared and evaluated. Field examples are presented and show that in some cases thermal plays an important role on stress reorientation. The quantified results of the model will give guidance on the fracture treatments and well plan.

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