| 摘要 |
A casing pressured operated, variable orifice valve is employed as the operating valve in a single point injection well assembly with tubing pressure (fluid) operated unloading valves acting above the operating valve to provide a continuous flow system. The operating valve includes a throttling range which extends between optimum injection gas pressure levels based on the amount of injection gas pressure available at the well head to thereby increase the overall efficiency of the system. The variable orifice valve includes a pressure charged bellows and a coil spring in series to produce a linear resultant load rate which in turn cooperates with contoured closure surfaces in the valve to produce a linear relationship between orifice size and injection gas pressure. Gas is thus injected into the production column or tubing at a rate which is linearly related primarily to the casing pressure with the throttling range of the operating valve producing a broad response in the gas injection rate. The injection rate is surface regulated by controlling the injection gas pressure at the wellhead.
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