Using the perforation shot density to secure uniform inflow to horizontal wells with multiphase production

This work presents two-phase gas and liquid flow in horizontal wells with perforation completion and radial inflow. The aim is to establish rational criteria for a perforation shot density which will allow the reservoir to be drained uniformly, in order to avoid gas or water coning. We consider only stratified wellbore flow, and the pressure loss between the reservoir and the well is assumed to take place in annular concentric zones surrounding the perforation cavities. This concept is based on the so-called horizontal-microwell model. The wellbore flow is modeled as one-dimensional, and the resulting equations are integrated numerically. Mean gas and liquid wellbore velocities, wellbore flowing pressure, liquid holdup fraction and perforation shot density as a function of position along the wellbore are calculated, and effects of production rates and formation permeability are included in the analysis. The results demonstrate that a uniform, perforation shot density can cause the reservoir to be drained at a higher rate at the downstream end of the wellbore than at the upstream end, and that the perforation shot density must decrease in a unique manner downstream in order to maintain a uniform production.