WAB® provides zonal isolation in an ultra extended reach, non pressure tight liner completion

Zonal isolation
WAB - Welltec Annular Barrier - Well Completion
  • Open-Hole Size 8.5″
  • Open-Hole Length 16,298 ft.


Extreme reach completions in the Middle East are enabling operators to increase reservoir drainage, but establishing effective zonal isolation in these environments can be problematic. One customer was challenged when trying to establish annular zonal isolation while deploying horizontal, non-pressure tight liners. In addition to the annular zonal isolation, it was essential that the liner had full rotational capability to overcome drag during the deployment along with maintaining the full liner torque capability; hence only rugged, robust components could be considered.

The client considered several zonal isolation solutions for field trial. Most solutions fell short of the technical specifications or operational limitations required including:

• Minimal running diameter to reduce drag
• Capable to carry the torque for liner rotation during deployment
• Able to seal and carry full annular ΔP even if set in a washed out hole
• Rugged design to endure sustained rotation and still operate (seal)
• Maintain a full bore ID
• Life of well design for the environment
• Anchoring force to the formation

One product, the Welltec Annular Barrier (WAB), met these criteria, and the operator selected the 812WAB2:2 for field trial. The WAB did not impose techni­cal limits on the liner installation and was able to meet the demanding specification to achieve zonal isolation.


The liner with the WAB installed was run without rotation the majority of the length and then rotated down the remaining 2,000 ft at between 30 RPM and 40 RPM The liner hanger was set and then the liner hanger running tool was released and retrieved. To expand the WAB within this non-pressure tight liner the Welltec® Multi-set Injection Tool (WMIT™) was utilized.

The WMIT straddles the solid liner section onto which the WAB is located and using surface pump control, applies the required expansion pressure locally to the straddled region. Multiple sets and re sets can be accomplished in the same run enabling multiple WAB’s to be expanded within non-pressure tight liners.

The WMIT was run on DP, depth correlated and using the rig pumps, the pressure was increased in steps over a 20 min time window to the final expansion pressure of 4,750psi. This pressure successfully expanded the WAB, providing the required zonal isolation at this depth.


This was the first deployment of the WMIT to expand the WAB within a non-pressure tight liner. On this operation the WAB endured sustained rotation in an extended reach, horizontal well without impacting the operational or sealing capability to the open hole.

The operator successfully completed the objectives for this well, using the capabilities of the WAB to overcome an extensive list of technical and operational specifications to successfully accomplish those objectives. A number of subsequent deployments have since been conducted in other geographical locations since their successful demonstration of the WAB’s capabilities.

The WAB endured sustained rotation in an extended reach, horizontal well without impacting the operational or sealing capability to the open hole.