GAS EXPANSION-INDUCED ACCELERATION EFFECT IN HIGH-PRESSURE GAS FLOWS NEAR A WELLBORE

In a high-pressure gas well, gas acceleration increases continuously as the gas moves and expands toward the wellbore. This expansion-induced acceleration effect in the linear flow of a high-pressure gas near a wellbore is studied. It is shown that for a given bottomhole flowing pressure, gas acceleration reduces mass flow rate, and for a given mass flow rate, gas acceleration decreases bottomhole flowing pressure. Acceleration steepens the pressure profile near the wellbore. When the bottomhole flowing pressure is decreased to a critical value, the gas mass flow rate reaches a maximum and the flow becomes choked. At choking condition, the gas pressure curve forms a vertical tangent at the wellbore wall and creates an unbounded pressure gradient. A further decrease in the bottomhole flowing pressure induces expansion shocks at the wellbore wall..