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ABSTRACT: In the frame of new technologies for boosting hydrocarbon streams, a relevant place can be taken by multiphase ejectors or jet pumps. The ejectors are characterized by a simple design, small dimensions, no moving parts, coupled with a high degree of reliability and low cost. The main disadvantages related to the use of multiphase ejectors are determined by their low efficiency and low rangeability. The efficiency of an ejector decreases in particular when the working conditions diverge from the design conditions. The ejector rangeability affects the use of ejectors in oil and natural gas production fields, due to the time changing characteristics of wells, owing to, for instance, natural depletion or water cut and GOR increase. The ejector rangeability can be enhanced using replaceable internals, which is the method used by ENI E&P at present. However this simple solution cannot be applied for cases such as sub sea applications. For these reasons the development of a variable asset multiphase ejector (VAME), which allows the geometry to be modified from outside, can be of a great interest for hydrocarbon boosting applications. This paper presents the results of an experimental activity during which the dependence of an ejector performance from its geometrical parameters was investigated. The most important design parameters are the nozzle diameter, the nozzle to mixing chamber distance, the mixing chamber diameter and the mixing chamber length. The experimental results have shown a significant dependence of ejector performances to the nozzle diameter, nozzle to mixing chamber distance and mixing chamber diameter
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 196440, โGiving a Boost to a Low-Pressure Gas Well by Installing a Gas Ejector,โ by Ping Wei and Brian Macdonald, SPE, KUFPEC, prepared for the 2019 SPE Asia Pacific Oil and Gas Conference and Exhibition, 29-31 October, Bali, Indonesia. The paper has not been peer reviewed. To further reduce backpressure on low-pressure gas wells and increase reserves in a mature gas field, a gas-ejector project was evaluated and proposed. Following on-site tests on several gas wells, the gas ejector was put into service successfully. Reservoir simulation estimates that 6.4 Bcf of incremental reserves will be achieved through gas-ejector installation by decreasing inlet pressure to 50 from 100 psi. The application of the gas ejector during a 2-year period to reduce backpressure has helped to improve economics in a mature gas field.
ABSTRACT: In the frame of new technologies for artificial lifting of hydrocarbon streams, a relevant place has been recently taken by multiphase jet pumps. These systems are characterised by a relative simplicity of structural design, absence of moving parts and small dimensions, which provide easy installation and management procedures during fields operations, coupled with an high degree of reliability and very low cost of installation, compared with other boosting systems. These capabilities have a cost to be paid, due to the complexity of fluid dynamic design, because multiphase streams are expected to be driven into this system. The high velocities and the large pressure drops needed for an efficient use of multiphase jet pump, give significant modelling problems both on the physical side and in the numerical solution of the system equations, and finally the results are very sensitive to stream properties, which rapidly change during the stream evolution inside the machine. Moreover, pipeline transients can have a noticeable impact on the jet pump performances, especially if slow hydrodynamic instabilities (i.e. hydrodynamic slug) takes place into the line where the jet pump is installed. The paper presents a complete model of multiphase jet pump, coupled with a simplified steady state simulator of a reservoir/well system. The model has been validated using several measured data coming from real jet pump applications in Italy and abroad. Various operational conditions can be simulated, providing either imposed well performances or reservoir characteristics. The model average error, for all the considered conditions, is below 20% of the measured jet pump performance, identified by the amount of flow which can be sucked by the system for given boundary conditions. Together with the validation results, a case study will be presented, where the model has been used to evaluate optimum sizing for a given set of operational conditions, as an example of the use of the simulation model for real field applications.
ABSTRACT The first world-wide (to our knowledge) field installation of a multiphase d c e ejector has been successfully applied in the Villafortuna oilfield (Italy) on 1996. Ejector installed at Villafortuna 4 (VF4) well increased its oil production rate by 30% and demonstrated the viability of the system as a reliable low cost-low size boosting system, with minimum impact on any existing facility, suitable for applications in existing fields or for new development both on-shore and off-shore. The paper describes the main steps of the R&D project, developed in collaboration with the University of Ancona, aimed at evaluating the suitability of ejectors as simple and low cost-low size boosting system for oil wells. In addition, the reliability of a computer code, developed by Agip and University of Ancona for the design of the ejector, is discussed. The paper also presents the activity of tuning for the software, based on a test campaign in which different geometries of ejectors were extensively tested, before with air and water at low pressures, in the laboratory of University (over 400 data points), and after with crude oil and gas in the Agip's multiphase loop of Trecate (over 200 data points).the tests have been executed varying pressure, liquid flowrate, gas-void fraction and outlet common pressure, both for the high pressure stream and for the low pressure stream, covering a wide range of process conditions. Following the good results obtained from the tests, the installation of a multiphase ejector at Villafortuna 4 well has been realized; The paper describes such installation as well as other studies under development. INTRODUCTION The ejector is a static machine in which a High Pressure Stream (HPS) is mixed with a Low Pressure Stream (LPS) in a properly designed mixing chamber. The mixture passes through a diffuser, leaving the ejector at an intermediate common outlet pressure (Fig. 1). The ejector is a well known equipment extensively used in many industries such as chemical industry (gas-gas ejectors) and nuclear (liquid-liquid jet pumps). The oil industry limited the use of jet pumps at the bottom hole as artificial lift system, using water or diesel as a power fluid pumped from the surface. For the bottom hole jet pumps the approach used is to treat the gas phase in the low pressure stream (suction stream) as a "liquid phase". This is usually correct for down hole jet pumps, where the gas carried under the liquid stream is frequently limited to small percent (5-10). This assumption is not valid for surface oil ejectors because the gas largely exceed this limit.
- Europe > Italy > Marche > Ancona Province > Ancona (0.46)
- North America > United States > Texas (0.28)
- Asia > Middle East > Israel > Mediterranean Sea (0.24)
To further reduce backpressure on low-pressure gas wells and increase reserves in a mature gas field, a gas-ejector project was evaluated and proposed. Following on-site tests on several gas wells, the gas ejector was put into service successfully. Reservoir simulation estimates that 6.4 Bcf of incremental reserves will be achieved through gas-ejector installation by decreasing inlet pressure to 50 from 100 psi. The application of the gas ejector during a 2-year period to reduce backpressure has helped to improve economics in a mature gas field. The YC13-1 gas field commenced sales from offshore platforms to Hong Kong and Hainan Island in 1996.