STRESS DISTRIBUTION AROUND A WELLBORE WHILE DOING HYDRAULIC FRACTURING
Ardhi Rofi Mufdhila, Bagus Endar B. Nurhandoko, Kaswandhi Triyoso
ITB
Abstract
Hydraulic fracturing has become an important method to increase the productivity of the well. Hydraulic fracturing will occur if the rock in the formation is given a tensile stress magnitude higher than the rock’s tensile strength. The insitu stress around the wellbore is unlikely to be tensile but some stress condition around the wellbore could lead to hydraulic fracturing given a pressurized fluid in the wellbore. We consider a two and three dimensional wellbore and assumed to be linear elastic and isotropic. Calculation and vizualiation of stress distribution around a wellbore has been done using finite element method. The model is applied by a minimum horizontal, maximum horizontal, overburden stress and the wellbore pressure. The wellbore pressure and the wellbore direction condition is variated. Some of the wellbore pressure data is derived from fracturing theory like Terzaghi, Daneshy, and least principal stress criterion. The data about the tensile strength of the rock around a wellbore is needed to predict wether the fracture will occur or not. The result show that there will be some minimum wellbore pressure and stress region that could lead into tensile failure that could lead to hydraulic fracturing. We also observed that the stress distribution in the horizontal well could predict wether the fracture will be transversal or longitudinal.
Keywords: Hydraulic Fracturing, Stress Distribution, Finite Element, Fracture Criterion, Well Direction
Topic: Earth and Planetary Sciences