Conventional intermittent gas-lift systems (CIGL) are usually employed for petroleum wells in mature fields when the reservoir pressure becomes so low that continuous gas lift is no longer efficient. The purpose of this experimental study is to investigate the dynamics and stability of the cycles for conventional intermittent gas-lift systems (CIGL) for petroleum wells. Presently, this kind of experimental data is still lacking in the literature. Following the advances achieved so far by Carvalho (2004) and Lara (2013) on this subject, further development of a laboratory-scale physical simulator was carried out for a CIGL, and a selected set of experiments was conducted. The laboratory apparatus for the CIGL is composed of three operational sets, representing, respectively, the oil reservoir, the production well and its controls, and the gas injection system. However, water and air are used instead of oil and natural gas as the produced fluid and the lifting gas, respectively. A microcontroller board is used for data acquisition of key pressure nodes and also for the actuation system of a gas-lift valve proxy. In addition, a variable inlet flow valve provides a range of productivity indexes for the mock-up reservoir. Three vertical pipes of different diameters are used as production tubing. A series of experiments were done to analyze the influence of the main parameters on the productivity of the CIGL system and to identify the stability conditions for the CIGL cycles. For this purpose, the fallback was determined for various conditions of the operational parameters, and the repeatability of the cycles was verified. The results from this study will help in the development of a mathematical simulator for the CIGL. Such a simulator may be extended to mature oilfield wells and applied to the design of CIGL cycles to achieve optimum production rates.

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