Well completion is the process of borehole preparation for the production. Cased and perforated slotted liner completion is used extensively as the completion configuration in the wells drilled into conventional sand formation reservoirs. Such completions may exhibit lower productivity ratios compared to the open-hole condition. The reasons include perforations collapse, flow convergence in the vicinity of the slots and perforations, and the formation damage caused by perforating. These effects have compounding effects as the formation damage magnifies the flow convergence effect and the flow convergence magnifies the skin buildup by the fines migration. In this study, a Computational Fluid Dynamics (CFD) numerical finite volume model was constructed for a vertical cased and perforated completion in a sand reservoir. Results include the skin values that were compared for the different slot and perforation densities. Stability of the perforation tunnels was considered as a variable in this research, and the results were summarized and analyzed in terms of the skin formed as a result of flow convergence. It was found that sanding in perforation tunnels and the resulting change in the permeability of the collapsed tunnel magnifies flow convergence skin significantly, especially in the lower shot densities and this added pressure drop can be very troubling. Results show in lower perforation densities higher pressure drawdowns may trigger sand production due to the tensile failure. Additionally, a parametric study was carried out on the sanding possibilities.
On the Sanding and Flow Convergence Skin in Cased and Perforated Slotted Liner Vertical Production Wells
Velayati, A., Roostaei, M., Sharbatian, A., Fattahpour, V., Mahmoudi, M., Lange, C. F., and A. Nouri. "On the Sanding and Flow Convergence Skin in Cased and Perforated Slotted Liner Vertical Production Wells." Paper presented at the 53rd U.S. Rock Mechanics/Geomechanics Symposium, New York City, New York, June 2019.
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