Compared to alternative production boosting solutions, the use of jet pump technology is one of the most cost-effective ways to improve production and extend the life of a mature oil field. The integrated approach discussed in this article effectively couples the evaluation, benchmark parameters, and optimization procedures of jet pump systems.
Jet pump (Fig. 1) is a proven artificial lift method that has been used since the early 1930s. Several thousand oil wells have been produced with jet pumps, and the number of its installations are increasing yearly. As the volume, size, depth, and deviation of producing wells continue to increase, the application of jet pump installations will also continue to increase (Pugh, 2009). Successful applications have included setting depths ranging from 500 ft to 19,000 ft and production rates varying from less than 100 B/D to 20,000 B/D.
Why Jet Pump Is Advantageous
There are numerous advantages of jet pump systems as compared to sucker-rod, electrical submersible pumps (ESP), or gas-lift systems and it has been discussed extensively in literature (S. A. K. et al., 2016; Pugh, 2009). One major advantage is that it will operate over a wide range of well conditions such as setting depths of as much as 20,000 ft and production rates of as much as 35,000 B/D. Some other advantages of jet pumps over other lift systems are as follows (Lea and Henry, 1999):
- Typically, no rig is required to retrieve free pumps. In many cases, this may be the primary advantage of jet pump systems as compared to the other systems
- Can operate reliably in deviated wells. They can adapt to tight turns up to 24°/100 ft in severity and are as reliable in deviated holes as in straight holes
- Have no moving parts and therefore no mechanical wear
- Can perform better in higher gas-to-liquid ratio wells than ESPs
- Standard jet pumps can operate successfully in temperatures as high as 500°F by simply using high-temperature elastomers for their O-rings and seal rings
- Have low maintenance costs
- Compact, simple, and rig-free design enables easy transportation to remote well sites
- Manufactured using corrosion-resistant alloy
- Ability to produce as low as 6 °API oil
Working Mechanism
The key components of a jet pump are the nozzle and throat. Power fluid is pumped at a given rate (QN) to the downhole jet pump where it reaches a nozzle with a total pressure, designated as PN (Fig. 2). This high-pressure fluid is then directed through the nozzle, which converts the fluid from a low-velocity, high-static pressure flow to a high-velocity, low-static pressure flow (PS). The low static pressure (PS) allows well fluids to be pushed by the reservoir at the desired production rate (QS) into the wellbore and pump and eventually to the surface (Pugh, 2009). The inflow-performance-relationship (IPR) / vertical-lift-performance relationship (VLP) [IPR/VLP] curves are generated by simulation software, which incorporates well schematic details and reservoir fluid properties and generates the curves at which the pump is to be operated. The output generated covers a range of numerous injection pressure and rates at which the surface pump will operate. High injection pressure and suitable nozzle/throat (N/T) combination tends to create an optimum differential across the nozzle which in turn creates more dragging effect causing more fluid to flow to the throat and then to the surface (Pugh et al., 2015).
Different types of fluids can be used as power fluid in a jet pump. Figure 3 shows how a power fluid can be selected based on the flowing wellhead conditions (Pugh et al., 2015). During recent years an increased number of hydraulic systems have changed from using power oil to using power water. Many of these changes were due to ecological reasons, code restrictions, town site locations, increased water cuts, or because the produced crude oil had a viscosity that was too high (Heinze et al., 1995).
Important Modeling Parameters
A series of simulations helps the operators decide the optimum injection and pressure at which the jet pump is tested. Some of the important parameters required for simulation modeling are as follows (Dollar, 1990):
- Pump vertical depth (ft): The true vertical depth to the end of the pump’s bottomhole assembly should be used. If the pump’s vertical depth is less than or greater than the perforation depth, then the pump intake pressure is corrected from the value of flowing bottomhole pressure.
- Producing gas-oil-ratio (GOR) (SCF/STB): The GOR of produced oil is a major factor in determining the size of throat, nozzle, and friction pressure drop of the return fluids.
- Injection pressure and injection rate (B/D): The injection pressure is selected as per the ratings of the surface facility. Injection pressure serves as a VLP in jet pump systems and is matched with the IPR of the well, thereby generating optimum production rates that can be achieved at desired injection pressures.
Economic Analysis
The selection and suitability of jet pump lift systems are governed by a variety of technical and economic factors. Jet pumps are low-cost items in any application, compared with alternative boosting systems, and can be used effectively to maximize the production performance. A case study was done on a dead well of a mature oilfield, which was completed with dual strings of size 2⅜-in. and 7-in. casing and producing from two separate formations. The upper formation being produced independently via short string was loaded up for almost 3 years, because the API and GOR from the formation were very low along with high water cut. To revive the well, a jet pump was installed in the short string in a sliding side door (SSD), and the short string was tested first with the long string being isolated (S. A. K. et al., 2016; Brown, 1977).
The results of the study: A dead well was successfully revitalized with the cumulative production of 380 B/D, i.e., an average of 100 BOPD and 280 BWPD, which was higher than the targeted production rates evaluated for this well. The conclusion drawn from this case study was that the jet pump was successfully deployed in the SSD of the upper formation with a 7A N/T combination.
Conclusion
The selection for a suitable artificial lift system has always been an integral part for production optimization and jet pump application is indeed an effective way to restore the deliverability of wells and thereby maximizing the production performance in a cost-effective manner. This article has summarized published literature which can guide the readers to find more information.
References
S. A. K., K. Farouque, A. B. Awan, and C. S. Louis (2016). Reviving the Production of a Dead Well by testing it with Hydraulic Jet Pump. SPE Middle East Artificial Lift Conference and Exhibition, Manama, Kingdom of Bahrain.
Brown, K. E. 1977. The Technology of Hydraulic Lift Methods. Vol. 1, Petroleum Publishing Company.
Dollar, F.O. 1990. Drill Stem Testing With Jet Pump. Presented at the SPE Latin American Petroleum Engineering Conference, Rio De Janeiro, Brazil, 14–19 October. SPE-21117-MS.
Heinze, L. R., Winkler, H. W. and Lea, J. F. 1995. Decision Tree for Selection of Artificial Lift Method. Presented at SPE Production Operations Symposium, Oklahoma City, Oklahoma, 2–4 April. SPE-29510-MS.
Lea, J. F. and N. V. Henry. 1999. Selection of Artificial Lift. Presented at SPE Mid-Continent Operations Symposium, Oklahoma, 28–31 March. SPE-52157-MS.
Pugh, T. 2009. Overview of Hydraulic Pumping (Jet and Piston). Weatherford CP.
Pugh, T., Khelifa, C. B., Fraser, K. 2015. First Ever Subsea Hydraulic Jet Pump System Used To Optimize Single Well Development Offshore Tunisia, Paper presented at 12th Offshore Mediterranean Conference and Exhibition in Ravenna, Italy, 25–27 March. OMC-2015-207.
