Application of SQP Algorithm to Optimize Perforation in Horizontal Wells

Optimal distribution of perforations on a horizontal well can assist in enhancing effective exploitation,stabilizing well productivity and controlling water cut.Considering the effect of drilling and perforation damage on the seepage in reservoir and the effect of friction and acceleration losses on the pressure drop in wellbore,a steady-state model is presented which couples the Darcy flow into perforations from the reservoir with the frictional and accelerated flow in wellbore.The model described here extends the perforated wellbore model developed by Landman.Based on the effect of perforation distribution on productivity and the inflow profile of a horizontal well,an optimization model is developed,in which the production of the horizontal well is taken as an objective function,the perforation distribution as decision-making variables and the inflow profile as constraints.SQP algorithm is applied to establish an optimization model of the perforated horizontal well to get the optimal perforation distribution.The results indicate that an optimal position distribution of perforations exists along the wellbore,which can effectively improve the profile of inflow rate along the wellbore and the production of the well.The perforation is denser at heel and toe,and the lowest density should be in the middle of the horizontal section,which can lead to maximum production.Under the constraint of uniform inflow flux,the perforation density should be increased from heel to the toe of wellbore,reaching maximum at the location 3/4 length of the wellbore.This research provides a new guideline for optimization of perforation parameters for horizontal wells.