Role of Fracture Face and Formation Plugging in Injection Well Fracturing and Injectivity Decline

We present a model to predict the initiation and growth of a fracture in the near wellbore region due to the combined influence of injection pressure, changes in pore pressure, thermal stresses and an additional pressure drop due to particulate plugging. Fracture growth and fracture face plugging are modeled as dynamically coupled phenomena. The results indicate that at a given injection rate, an increase in plugging leads to significant increases in fracture half-length. In the absence of thermal effects the injectivity of fractured injectors is shown to be independent of the water quality and the permeability of the formation. Results also demonstrate that a longer fracture does not necessarily imply an increase in injectivity if there is significant permeability impairment due to plugging of the fracture face. The combined effects of particle plugging, phase mobilities and thermal stresses need to be properly accounted for in predicting the performance of injectors.