An Innovative Solution to Regain Well Integrity and Deepening Gas Injection Point - Maximizing Production and Rectifying Multiple Tubing Leaks with a Low-Cost Solution

Abstract

Multiple tubing leaks have become one of the major issues in brownfield operations especially on wells that have already exceeded their original production lifetimes. This integrity issue becomes more challenging when the leaks occur close to the tubing hanger due to the space constraints in fixing them.

In addition, high water cut wells with low reservoir pressure require continuous artificial lift where tubing integrity is crucial to allow the injected gas reach to the target injection depth. Conventionally, tubing packoffis used to isolate tubing leaks occurring in short intervals while longer ones require coiled tubing straddle with higher installation complexity. However, some wells need deeper injection than the initial completion design. The wells might not be able to flow efficiently without deepening the gas lift point to optimize production to the full extent.

In finding the solution to all three issues; multiple tubing leaks, low reservoir pressure and the requirement for deeper gas lift point, multiple solutions have been proposed and evaluated. Traditionally, workover is considered the best method to replace degraded tubing and to deepen gas lift mandrels.

This paper discusses an innovative and low-cost solution which has been proposed and successfully executed in a dual strings completion. A conventional coiled tubing straddle is installed in the long string as Coiled Tubing Gas Injection Straddle (CTGIS) for gas lifting and the short string is used for oil production. This system replicates the barrier envelope as per the production casing annulus during gas lifting operations and also deepens the lifting point through a sliding sleeves door (SSD). Injected gas mixes with liquid through the SSD from the long string allowing continuous flow from the short string. This low-cost and quick solution enables the well to be restored to production.

This paper includes the gas injection straddle system that consists of engineering design, installation and testing, resulting in a two-fold incremental increase in the production rate and costing only one-tenth of recompleting the well. This has increased the chance of success to restore most idle wells with tubing leaks and opens the door to enhance the existing production.