Calculation Method of the Productivity of Partially Perforated Vertical Well

To accurately calculate the productivity of partially perforated well and provide theoretical foundation for optimization of perforation scheme,McLeod’s perforation geometric model is modified to dual radial flow model.Then,by considering penetrated and unpenetrated damaged zone,productivity calculation methods of partially perforated vertical well in isotropic reservoir was established based on the principle of fluid mechanics in porous medium and equivalent flowing resistance method.On the basis of this work,the productivity calculation methods of partially perforated vertical well in anisotropic reservoir was established by transforming anisotropic reservoir into isotropic reservoir based on the principle of fluid mechanics in anisotropic reservoir.Sensitivity analysis of the perforation parameter of partially perforated vertical well shows that perforated degree,perforation length,shot density and compaction degree have great effect on the productivity when the perforation has a perforated degree less than 70 percent,perforation length less than 80 cm,shot density less than 20 shots per meter and a compaction degree more than 75 percent.But perforation phasing,perforation diameter and crushed zone thickness have little effect on the productivity.The productivity of a reservoir with penetrated damaged zone is less sensitive to reservoirs with partially penetrated damaged zone.An example is provided and the difference between corresponding results of new method and skin method is about 5 percent.Results show that perforation length,shot density,perforation diameter,phasing,crushed zone thickness,compaction degree and perforated degree have a nonlinear relationship with productivity.