Statistical and numerical investigation of gas/liquid flow in the near wellbore region

Horizontal wells are considered a relatively advanced method of drilling that maximize the reservoir productivity index because of having higher contact area between the formation and the wellbore. The reservoir productivity index relies on the properties of the reservoir flow, which itself is highly dependent on wellbore geometry, completion technique, and specific reservoir parameters. Multiphase flow model through horizontal near-wellbore region has been conducted to analyze the effects of skin zone diameter (damaged region) and the influence of perforation distribution on enhanced oil recovery. Statistical analysis was coupled with numerical simulation in order to expand the investigation on fluid flow at near wellbore region. The statistical analysis is used to investigate the effect of several parameters such as, the skin zone diameter penetration space, angle and depth as well as the perforation diameter on the injection build-up pressure and the time needed for reaching steady-state flow condition. Design Expert Software (DoE) version 11 package has been used to determine the numerical simulation runs using the ANOVA analysis with Box-Behnken Design “BBD” model. Forty-one numerical runs have been generated using DoE to achieve the whole statistical analysis. ANSYS-Fluent software 18.1 has been used to carry out the numerical simulation in the porous media tunnel by applying the volume of fluid method (VOF). The numerical and statistical analysis showed a clear view of the effect of each investigated parameter on the injection build-up pressure and time required for reaching the steady-state. In addition, two correlations have been obtained from the statistical analysis and numerical simulation in which can be used to predict the injection build-up pressure and the required time to reach steady state for different scenarios. This study will be very helpful in choosing the optimal perforation distribution and understanding the multiphase flow behavior in horizontal near wellbore region.