Optimizing well completion for maximized oil recovery in offshore horizontal wells: insights from simulation-based analysis

Well completion design is considered one of the most influential factors controlling well productivity, especially in horizontal wells, where the formation damage potential and operational constraints is higher compared to the vertical well. The integrated flow simulation-based evaluation of completion type, perforation design, and completion-string geometry that quantitatively provides guidelines to optimize well performance has been less attended. In this research three horizontal wells situated in an offshore oil field are investigated to complete in various manner towards production optimization approach. Numerical reservoir and wellbore simulations were conducted at different wellhead pressures. According to this, a sensitivity analysis was conducted for the perforation parameters (perforation density, length, and diameter) and the completion string (internal diameter and length). Simulation results indicate that open-hole completion gives considerably higher production rate compared with cased-hole completion (increase of 96.8, 94.0, and 126.8 BPD for three wells). Under conditions of appropriate shut per foot perforation obtained from petrophysical properties, flow simulation showed that perforation density of 8 SPF along with maximum length and diameter of perforation yields the maximum rates. Sensitivity analysis reveals that an increase in internal diameter of the completion string improves production, while an increase in the length of tubing increases the wellbore pressure losses resulting in reduced productivity. For instance, increasing the length of tubing by 400 feet resulted in a drop in production by 0.04%, 0.13%, and 0.11% for three wells.