The Oudna Field is located approximately 80 km. offshore Tunisia (Figure 1). Successful application and optimization of an artificial lift system for this field required a considerable amount of evaluation prior to implementation, in order to take into consideration three specific features of the prospect:
The high cost of intervention once the well was on production.
The need for water injection for reservoir pressure maintenance.
Limited space available on an FPSO.
After extensive study of the various artificial lift alternatives available, the decision was made to install the first sub-sea hydraulic jet pump system, capable of producing 25,000 bpd, because it afforded the following advantages:
A reliable low maintenance system that allows for flexibility in lift volumes.
The ability to operate for extended periods of time without the need for intervention.
The ability to use a common system for both the power fluid and the field water injection fluid, thus minimizing production equipment space requirements and surface facility complexity.
In this paper the authors explain the need for a long life system, the reasons for selecting jet pumps, the considerations in the design of the jet pump, its installation and operation. The process used for the optimization of the jet pumping system is discussed.
Initial field economics on Oudna was carried out based on a $27 / BBL pricing. With this oil price, under any circumstances the Field was likely to be Marginal. Although confidence existed that the Oudna reservoir modeling was sound this in turn had indicated that both reservoir pressure support and an artificial lift production mechanism would be required to keep oil production levels to that required.
Given that the field is in 270m of water and around 80km from shore then both the Production Handling and Artificial Lift options were going to be limited.