This paper presents the performance and compatibility of using jet pumps with hydraulic pumping bottom-hole assemblies that were designed to work with hydraulic piston pumps in an attempt to reactivate idle wells in a heavy oil reservoir, offshore South-West Trinidad. The resilience of the already installed hydraulic bottom-hole assemblies made it easier to select jet pump as the artificial lift method for reactivation.

Jet pumps were designed with dimensions to fit in the hydraulic bottom-hole assemblies. Assemblies were modified by using a 13 ft length of 2" pipe inside them to ensure that the seals in the pumps and the polished sections of the assemblies meet at the same depth. The production string from the triple string completion was isolated since only 2 completion strings were required for operation, leaving the power oil injection and fluid return strings active. Jet pumps were installed on 4 wells. Performance was monitored using sonologs to determine fluid levels and clamp-on ultrasonic flowmeters to determine injection and production rates.

Results showed that drawdown was occurring and production was obtained from all 4 wells during the first 4 months of operation since submergences were lower than the static levels. After this period, the submergences of 3 wells increased to the static levels and test rates showed that these wells were not producing. The submergence of the 4th well was fluctuating and tested 76 bpd. On inspection, it was discovered that the throats and nozzles of the other 3 wells were plugged with seal fragments from the surface power oil pumps. The jet pumps were cleaned and reinstalled after which the submergences dropped drastically within the first month of returning to operation. From these results, it can be concluded that the jet pumps are compatible with the modified hydraulic pumping bottom-hole assemblies. All 4 idle wells completed in this heavy oil reservoir were successfully reactivated however the performance was affected by plugged nozzles and throats of the jet pumps by seal fragments from the surface power oil pumps. Submergences could be reduced to optimize all 4 wells by changing the nozzle and throat sizes to achieve optimum performance and production rates with the maximum power oil injection pressure of 2400 psi.

This paper describes the experience of using jet pumps in the East Soldado field to reactivate heavy oil wells by making minor modifications to the existing hydraulic bottom-hole completion that was designed to be used with hydraulic piston pumps. The use of jet pumps was motivated by the need to reduce workover and operating costs together with the demand to increase oil production. This modification was successful based on the production and monitoring parameters obtained.

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