Application of Jet Pumping Technology for Offloading a Killed Well in a Gas Condensate Field - A Case Study

Abstract

This paper describes a trial jet pump application for offloading a killed well. The Well-2A was naturally producing an average 1650 BCPD and 1.54 MMSCFD from two separate formations via dual strings of size 2-3/in. in a 7 in. casing. It later required a workover job because of tubing string and packer leakage. The well was recompleted with a single string of 3-1/2 in. tubing in order to produce both formations together. The well was killed and initially kicked-off by injecting nitrogen, but it was unable to flow even after continuous pumping of 4,000 gallons of nitrogen. Therefore, jet pumping technology was applied to offload the well.

A jet pump was run in the well on tubing, which was equipped with a bottomhole assembly (BHA) for a downhole jet pump. It was installed in a free-style after opening the swab and master valve of the Christmas tree. Once, the jet pump properly seated in the BHA housing, high pressure power fluid was pumped into the wellbore to lift the kill fluid.

Production results indicate that the killed well was successfully offloaded with cumulative production of 690 BPD, which was higher than the targeted production rates evaluated for this well. Freestyle jet pump deployment has achieved the expected performance and reliability. Moreover, the jet pump can easily be re-optimized by reversing it out to change the nozzle and/or throat without requiring a slickline job. Hence, the jet pump was found to be the most economical artificial lift method and the trial achieved more than expected results.

Introduction

Oil and gas wells experience many issues, including well-performance, damage in completion strings or fished tools which sometimes require a workover. In all these cases, killing a well is not a problem; the tricky part is to revive the well after the workover. Usually, a workover is performed after killing the well with completion fluids. After a workover, nitrogen kick-off is the most common method to recover the completion fluid and reduce the hydrostatic head above perforations which results in the flow of fluid from the formation to the surface. In this method, nitrogen is pumped across different depths of tubing starting from the nearest point of surface, and then goes deeper until the formation depth is reached (Lea et al. 2008). However, the wellbore pressure is not enough to lift the well fluid to surface, so pumping nitogen is not always an efficient technique for offfloading a well. In this paper, a hydraulic lift system i.e., jet pump was deployed downhole in a mature well to recover the completion fluid and to produce the well simulatenously.