SIMPLIFIED AND RAPID METHOD FOR DETERMINING FLOW CHARACTERISTICS OF EVERY GAS-LIFT VALVE (GLV)

The current API testing method requires quite amount of time to complete a Gas Lift Valve (GLV) test. The API method was developed for the GLV manufacture rather than the producer. There is a need for a method of testing oriented toward the producer. In the proposed method of testing which is based on the concept of blow-down; the valve is tested in a few seconds. The Thornhill-Craver equation (TC) has been modified since the flowing area is constantly changing and is not necessarily equal to the port area. Note that TC equation primarily developed for the chokes and gas passage though chokes. This method can easily be applied for the GLVs with check valve on them as well as cross-over seat valves and all different GLVs with different structural architectures. It can be applied to tubing retrievable as well as wireline retrievable GLVs. The current proposed industry instrument is not capable of measuring the performance of cross-over seat valves but this method can perform the test on that smoothly. The sample rate in this method is 100-10000 samples per second to achieve the highest possible accuracy for the measurement. This method is aimed to be accurate in the critical flow region where there is no effect of downstream pressure on the flowrate. The effect of temperature on the valve opening and closing pressure has been investigated as well. This method of testing provides an opportunity to other applications. This method will let the user to evaluate tapered seat orifices as well as sharp-edged. Tapered seat can pass more gas than sharp-edged seat at the same ball distance from the rest. This method is capable of measurement of the performance of cross-over seat valves, and GLVs with check valves. This method can be furnished at a fraction of the cost of the API method. This is another reason to announce such method. The development of such testing method is for the favor of the producer. The manufacture just adjusts the GLV performance based on API method for the producer’s need and this method assures the producer of producing predicted amount of liquid or not. In this experimental work, several hundred flow tests ran using different GLVs with various port and ball sizes to quantify the flow behavior at critical flow conditions. It has been found that the discharge coefficient is changing based on flow velocity profile (Reynolds number) and upstream pressure.