The Stress Calculation of Sidewall Rock in Hydraulic Fracturing Basing on Damage Theory

Abstract

The sidewall rock area was divided into destruction zone, damage zone and elastic zone, considering that the fracturing fluid can cause sidewall rock damage and change the stress status of sidewall rock. The stress distribution calculation models for every zone were established basing on elasticity and damage mechanics. The relationship between radial stress, circumferential stress and destruction radius, damage zone was calculated. We can conclude from the calculation results that the radial stress and circumferential stress will increase with the distance away from the axis of wellbore increasing, and radial stress is greater than circumferential stress in destruction and damage zone. However, in elastic zone the radial stress and circumferential stress will decrease with the distance away from the axis of wellbore increasing. The radial stress approaches the maximum horizontal principle stress, and the circumferential stress approaches the minimum horizontal principle stress at last.