Abstract
Particle plugging of wells in the near wellbore region can have an important influence on the initiation and propagation of thermally and hydraulically induced fractures during water injection. Fracturing in turn can significantly influence the rate of injectivity decline in water injection wells. Development of models that elucidate the role of plugging of the fracture face and surrounding formation on the growth of fractures, and the resulting injectivity behavior, is an important research need. 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 due to the injection of cold water, 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 wellbore plugging can significantly affect the initiation of a fracture. Further, plugging of the fracture face itself can have a major impact on the growth of the fracture, and the overall injectivity of the well. It is found that at a given injection rate, an increase in plugging leads to significant increases in fracture half-length. 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 effectiveness of fracturing as a well-stimulation mechanism can be seriously diminished due to fracture face plugging in injection wells.
