ABSTRACT
In one of the previous studies, the mechanical properties of filter cake have been investigated to evaluate the pressure needed to remove the cake to initiate the production.They concluded that the mud cake behaves elastically with a sharp change to plastic behavior. In fact, in certain pressure ranges the mud cake behaves elastically and contracts and expands with respect to wellbore pressure, but an elastic failure is not likely to happen for the cake and its failure takes place at a higher pressure level. In this work we have assumed that the mud cake is part of the formation with different properties to the main formation. Based on this assumption the mud cake behaves elastically up to the fracture initiation in the rock (Figure 1). In our analysis, we have estimated the hoop stress on the surface of the formation based on the pressure exerted by the mud to the mud cake. Once the formation is fractured, the mud cake will form the bridge over the crack. The effect of mud cake thickness and its compressibility on hoop stress value has been investigated in this study. The more hoop stress in the formation the more robust the formation is to fracturing.
