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Temporary plug to maintain pressure control

The Challenge

A client in the Middle East approached Aubin requesting a solution to maintain pressure control whilst replacing a leaking valve on the wellhead. The client wanted to reduce operational costs associated with workover rigs and apply a chemical plug solution, rather than a mechanical one, whilst still maintaining safety standards.

The challenging part of this request was providing a chemical solution that would be successful in the high salt content of the produced water used as a base fluid. Previous technology used by the client had experienced failures in these demanding conditions and using fresh water would have caused a significant increase in cost for the client.

Aubin’s AXI‐Zone was recommended, due to its ease of application, tolerance of harsh conditions and cost effectiveness. This technology works by pumping a low viscosity liquid in place via coiled tubing or bullheading, which then forms a very viscous plug under well conditions, effectively controlling pressure from the formation. Flexibility in pumping time is ensured by adjustment of the AXI‐Zone retarder loading.

What Happened?

Aubin’s technical team worked with the client to optimise the dosage to suit the well conditions and base fluid. In this case, the well temperature was 99°C and required a setting delay of 60 – 75 minutes to place the plug. The client was satisfied with the testing provided by Aubin that showed AXI‐Zone could achieve this delay before setting in the well.

During the operation, AXI‐Zone was pumped into place via coiled tubing. The plug was allowed to set for 24 hours, before a successful positive pressure test was conducted with 1500psi differential pressure. Including hydrostatic pressure, this totalled to around 6,000psi on the plug without failure.

The replacement of the leaking valve on the wellhead was conducted successfully and safely. Once complete, AXI‐Zone was quickly removed with the use of acid, so the well could be put back online.

The Result

Aubin’s AXI‐Zone successfully formed a temporary plug, maintaining pressure control and allowing the wellhead to be quickly and safely repaired. Using this chemical technology meant that a workover rig was not required, providing an efficient and cost effective solution for the client.

The client was very pleased with the responsive technical support received from Aubin along with the outcome of the project and plans to use AXI‐Zone for future workover operations.

To learn more about AXI-Zone, please click here

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