Stresses and Displacements Around Hydraulically Fractured Wells

The stress and displacement fields around hydraulically fractured wells have been calculated. These calculations, which are based on the linear theory of elasticity for homogeneous isotropic media, lead to two useful conclusions:Hydraulic fracturing significantly changes the stress state around the well, removes the stress concentration caused by the wellbore, and reduces the maximum compressive stress in the rock matrix.If a small fraction of the near wellbore region of a fracture is left unpropped, the fracture will close at the wellbore due to elastic deformation of the unpropped rock. Introduction This paper deals with two questions related to the application of the widely used well stimulation technique, hydraulic fracturing:Does hydraulic fracturing remove the stress concentrations which exist due to the presence of the wellbore and the perforations? perforations?How much of the near-wellbore region of the fracture can be left unpropped without the potential stimulation of the well being lost? It is convenient to consider these two questions in the same paper because they can both be analyzed with the same theoretical calculation. In some deep, abnormally pressured wells, it is necessary to limit the drawdown to avoid producing formation fragments caused by the producing formation fragments caused by the failure of the rock due to the very high stresses induced near the wellbore. These high stresses occur because of the borehole and the perforations. Hydraulic fracturing can decrease the stress around the wellbore by increasing the productivity index of the well and reducing the drawdown necessary to obtain a given production rate.