Estimation of flow coefficient for subsonic natural gas flow through orifice-type chokes using a simple method

Choke valves are critical elements in gas production facilities. Malfunction or failure of a choke valve can seriously affect safety, the environment and production rates. Choke is a device installed at wellhead or down hole to control the flow rate for maintaining sufficient back pressure to prevent formation damage, to prevent water/gas coning, to stabilize the flow rate and to produce the reservoir at the most efficient possible rate. In this work a simple-to-use method is developed to estimate the choke flow coefficient for natural gas subsonic flow through orifice-type chokes as a function of Reynolds number and the ratio of choke diameter to pipe diameter. The results can be used in follow-up calculations for rapid estimating gas passage through a choke under subsonic flow conditions. Estimations are found to be in excellent agreement with reported data in the literature with average absolute deviation being less than 0.4%.