A segmentally numerical calculation method for estimating the productivity of perforated horizontal wells

Owing to the non-uniform inflow profile,it was difficult to estimate the productivity of horizontal wells accurately by traditional analytical equations or calculation methods with constant production index.The well is partitioned into many segments on the assumption of homogeneous formation.The whole three-dimension flow is divided into three parts using the pseudo-three-dimension method: flow from infinite boundary into a vertical fracture,radical flow around the well bore,and convergent flow through perforations.Taking the influence of formation damage into account,a correlation equation between reservoir flow rate and pressure difference is obtained for each segment.According to the influence of perforation inflow on the main flow,the pressure drop along the horizontal well is attributed to friction and acceleration losses.A general pressure-drop expression is established based on the principles of conservations of mass and momentum.The resulting models,coupled together,are validated by the close match between numerical calculation results and field data.The calculation results also show that the perforation-influx rate increases gradually from the toe to the heel of the horizontal well bore.