The nature of the crushed zone is important to the overall hydrocarbon flow following perforation. This work examines the nature of such formation damage using testing and simulation. Furthermore, the crushed zone's effect on overall formation productivity is also discussed.
Using a shock hydrocode, the crushed zone is compared and contrasted by thickness and density for deep penetrating (DP) and big hole (BH) charges. The results are compared to information obtained from flow-laboratory-created crushed zones from previous perforation tests. Information from flow-laboratory testing is then used as input to model flow through the crushed zone and hence measure permeability. A study of the relative effect of the crushed zone on skin effects, including its relative contribution to the overall perforation skin, is presented.
Simulation results indicate that the crushed zone from a DP charge is much thinner than the BH charge layer. These results are obviously charge dependent (in the same class). Visual observations show a structure that differs in the crushed zone from the ambient zone around the perforation. A flow model is derived, which accounts for the transition of hydrocarbon flow through the crushed zone. The crushed zone results are then considered in overall flow production, demonstrating when its effect becomes applicable. These results are reflected in a charge penetration code. Combining all of the information, a recommendation is made to help achieve optimal production downhole.