TX 75083-3836, U.S.A., fax 01-972-952-9435.
AbstractA specific area under water injection in the Carmópolis field, Brazil, is been considered a candidate area for a polymer pilot project for mobility control. A reservoir characterization and an evaluation of the polymer performance in this high heterogeneous reservoir were required. For this purpose, radioactive, fluorescent and chemical tracers were applied associated with polymer in a reduced area. The tracer technology has an enormous potential use in Petrobras scenario and this Carmópolis field application was an opportunity to obtain know-how. This paper describes the basic steps from the laboratory tests to the final application including design and programming of field operation. The interpretation of the results using a new approach is also addressed.
A model to calculate the theoretical critical flow rate of nitrogen (N 2 ) or natural gas through a Venturi gas lift valve is described herein. This new model considers real-gas effects not only in density calculations but also in other thermodynamic properties that are relevant during gas isentropic evolution.For the properties of N 2 , the Bennedict, Webb, and Rubin (BWR) equation of state and an accurate correlation for the idealgas isobaric heat capacity were used. For natural gas, the Dranchuk and Abou-Kassem equation, which reproduces the well-known Standing and Katz chart, was used, and, for the ideal-gas isobaric heat capacity, it was assumed that the natural gas was a mixture of methane and ethane only, their individual ideal-gas heat capacity being calculated by updated correlations.To validate the use of the proposed equations of state, a comparison of calculated with experimental or reference data on properties of N 2 and natural gas (including pure methane and some relevant mixtures) was performed with very good results for N 2 and for natural-gas compositions usual in gas lift operations (dry gas with very small amounts of contaminants). For natural gas with moderate amounts of N 2 and carbon dioxide (CO 2 ), accurate results were obtained after correction of critical conditions and of ideal heat capacity. The model was also compared with other theoretical models found in the literature, which use compositional approaches for natural gas, with excellent results. Some experimental results obtained with commercial Venturi valves manufactured in Brazil are also presented.
Summary
The Venturi valve represents a significant advancement in the technology of gas lift in petroleum wells. Its use is expanding, and an understanding of the theoretical and practical aspects is fundamental to maximize the benefits of its application. The application-related aspects are reasonably well-covered in the literature; however, to achieve good performance and promote the expected benefits, some valve-design aspects have to be taken into account. This paper describes key points, including a recommended Venturi geometry, the influence of several Venturi design parameters on performance, and an analysis of the role of the check valve. The design guidelines provided in this work are supported by experimental tests performed at Petrobras’ Gas Lift Valves Test Unit and by sizable experience with Venturi valves after more than 600 valves run in wells or tested.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.