Abstract: The flow of the differential section at the perforation of horizontal well was analyzed in the paper. According to the continuity equation, themomentum equation and energy equation of gas and liquid phase, the mixture lossmodel of the gas and liquid phase under the condition ofhaving nomass exchanging between gas and liquid, isothermal and steady flowwas gotten. The mixture loss of horizontal bore through the model was calculated.The result indicated that the influx angle had more influence to themixing loss. Under the condition of no influence to the output, we should do ourselves best to adopt the influx angle smaller than 90 degrees. Thismodelhad the directive significance to research the change of traditionalperforationway, sidetrack horizontal well and fracturing horizontalwel

Key words: horizontalwel, l wellbore pressure drop, mixture loss, influx angle