Abstract

When the natural energy of a reservoir is not adequate to lift the wellbore fluid to the surface, it is necessary to use an artificial lift system that supplies the additional energy required to continue the exploitation of reservoirs.

This paper presents a trial jet pump application in the dead well of a mature oil field. The well was completed with dual strings of size 2-3/8 in. in a 7 in. casing and was producing from two separate formations. Both formations, despite of having produced for a considerable amount of time, have high reservoir pressures at present. The upper formation being produced independently via short string was loaded up for almost three years, because the API and Gas Oil Ratio (GOR) from the formation were very low along with high water cut. The lower formation had a substantial amount of gas with no water cut and was producing at significant oil rates. However, the formation being produced through the long string did not flow after shutting in for a Bottom Hole Pressure (BHP) survey. The well was unloaded by reducing surface back pressure, but it exhibited slugging behavior and an increased oil API and therefore was abandoned.

The test with hydraulic jet pump was justified by the need to revive production without a work-over. Thus, 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. After the testing of short string independently, an SSD connected to the long string in the middle of two packers, was opened so that both formations can be produced from the same short string.

Based on the results, a dead well was successfully revitalized with the cumulative production of 380 BPD i.e., an average of 100 BOPD and 280 BWPD, which was higher than the targeted production rates evaluated for this well. Apart from this, downhole pressure data was gathered with the objectives to observe the potential of reservoir and to assist the operator for making the decision of installing jet pump on the well with or without a worker-over. Nevertheless, this technique allowed the operator to install jet pump through slick-line and consequently saved the cost of a work-over. Hence, jet pump was found to be the most efficient Artificial Lift System (ALS) and the trial achieved more than the expected performance.

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