The Ejector Technology in Oued Zar Plant

Abstract

The Oued Zar process is continuously progressing and growing. In fact, the exploitation of the new well reserves engendered an important increase of the quantities of oil and gas to be treated. One of the major issues associated to this evolution was to optimise the process and to consider environmental impact. The purpose of this work consists on the application of the ejector technology in real case. The ejector is a pump-like device that uses the Venturi effect of a converging-diverging nozzle. It converts the pressure energy of a driver fluid to velocity energy. A low pressure zone is created and entrains a suction fluid. After passing through the throat of the injector, the mixed fluid expands and the velocity is reduced, thus recompressing the mixed fluids by converting velocity energy back into pressure energy. ENI Tunisia had previous experience using the ejector technology in Oued Zar plant. The Ejector design is specific. It's intended to suit an individual case requirement for maximum operating efficiency. Thus, for the conceptual phase, first step of the project, real field data (the gas outgoing of separator and the driver gas characteristics) are required. This information is obtained by CPG analyses and pressure measurement. Then, the performance of ejector is evaluated for different drive flow. The second step consists on field installation. The ejector started up in December 2006. The excellent results obtained during the test were confirmed. The ejector is still working with high performance and very low maintenance cost. This experience confirms the first field installation of ejector was successfully accomplished in the Oued Zar oilfield in 2006 and encourages using it for other similar projects.