Investigation of Skin Factor Around the Wellbore of Vertical Wells using the Developed Numerical Model for Single-phase and Two-phase States

Formation damage in hydrocarbon reservoirs around the wellbore is inevitable, and it can happen from the earliest stages of drilling to the latest hydrocarbon recovery stages by tertiary enhanced recovery methods. Numerical simulations of production behavior around wellbore perforation in single-phase and two-phase states have been conducted by the CFD method to investigate the effect of perforation geometry on formation damage. Moreover, formation damage due to drilling mud penetration into the perforations by dispersion mechanism has also been analyzed. The results of the simulation were validated in good accordance with the published data. Based on simulation results, although perforations enhance the drilling mud penetration damage, especially for perforation lengths up to 20 cm, they can effectively reduce perforation skin if they become adequately cleaned. Perforation density, length, and diameter have the most pronounced effect on reducing the skin factor. There is almost a linear relationship between skin factor and clean perforation diameter. Since larger diameters come with shorter lengths, perforation optimization is required according to casing material, hole size, rock mineral, and perforation technology available.