Thermal-Poro Elastic Stress Effect on Stress Reorientation in Productionand Injection Wells

摘要

Stress reorientation is an important issue for the cuttings injection batching, refracturing design and stimulation candidatewell selection. Long term production/injection causes the principal stresses to reorient. Temperature differences and porepressure differentials induce thermal elastic stress and poroelastic stresses. These induced stresses are the fundamentalreasons for the reorientation of the stress field. A model and numerical scheme are developed to study the effects of thermaldifferentials and pressure differentialss on stress reorientation. The model couples thermal diffusion and convection withhydraulic diffusion to obtain the temperature distribution reflecting the cumulative impact. The effective poro-elastic andthermo-elastic stresses result from the 1-D displacement equilibrium equations in a radial system. The 3-D in-situ analyticaleffective stress is superimposed on the 1-D solution. Application of this methodology simplifies the modeling of the 3-Dstresses in a deviated borehole. The method makes it practical to obtain the stress distribution at any giveninjection/production time. The thermal stress and poro-elastic stress effects on the stress reorientation are compared andevaluated. Field examples are presented to show that in some cases the thermal stresses play an important role on stressreorientation. The quantified results of the model will give guidance on fracture treatments and well plans during injector orproducer construction.