Flow Model of Variable mass Gas-Liquid Stratified Flow in the Wellbore of a Horizontal Hole

The mechanism of the flow pattern transition and the method of calculating the pressure drop of the gas-liquid two phase flow in a horizontal borehole can be obtained by the extention or modification of those of the gas-liquid two phase flow in a general horizontal pipeline because of the samilarity and the difference between the two flows. when there is the inlet flow through perforation channels, the gas-liquid flow in a horizontal borehole is variable mass one. The criterion of the flow pattern transition of the variable mass gas-liquid flow from stratified flow to non stratified flow was derived based on the fast growing mechanism of the interfacial wave of gas phase and liquid phase. And The formula of calculating the pressure drop of the stratified flow is also presented. It is shown that the condition of the flow pattern transition of the variable mass gas-liquid flow is different from that of the gas-liquid flow in general horizontal pipeline; the pressure drop of the former is greater than that of the latter , and the greater the flow rate of the inlet flow, the greater the pressure drop.