A client in the Middle East planned to side track, drill, and complete a highly depleted reservoir as a water injector to provide pressure support to an offset oil producer. The reservoir contained several fault/fracture risk zones.

The 9-5/8” window was milled at 6,000 ft (1829 m), but losses were encountered while drilling the 8-1/2” hole section, at which point a 7” liner was deployed. As losses were expected during cementing, the client planned to isolate the toe prior to drilling the final reservoir section with a 6-1/8” bit. Alongside two third-party inflatable packers, the client used Welltec’s innovative 812 Welltec® Annular Barrier (WAB®) for zonal isolation.
One reason the client chose the WAB is its ability to rotate during deployment. High rotation is often necessary for shallow vertical depths with long horizontal sections as in this case.

The upper inflatable packer would be set at 8554 ft (2607 m) MD, and the WAB and lower inflatable packer would be set at 11,200 ft (3414 m) MD and 11,500 ft (3530 m) MD, respectively, to isolate the losses between 9183 ft (2799 m) and 9754 ft (2973 m). During the initial run, the liner, which included both the lower inflatable packer and the WAB, hung up with rotation up to 30 rpm. For the second run, adjustments were made, and, from 7,500 ft (2286 m) to 11,500 ft (3530 m), the liner was rotated at 50 rpm to reach target depth.

The primary cement was pumped with no returns to surface. Pressure was increased to expand the inflatable packers. After, the WAB fully expanded at 5,000 psi with a continuous leak rate of 250 psi/min. The consistency of the leak rate when attempting to set the WAB and the continued communication with a nearby well indicated that at least the upper external control packer was not set.
The upper inflatable packer was then set. The 5-1/2” drill pipe was pulled out of hole, and the well remained on losses. When drilling out the cement plug, no losses were observed, indicating the toe was isolated. The 6-1/8” hole was drilled.

This case demonstrates the robustness of the 812 WAB’s deployment. The long lateral required it to be reamed for 4,000 ft (1219 m) at 50 rpm and 5.5 bpm to effectively reach the target depth.

The WAB’s metal-to-rock expansion within carbonate alongside the inflatable packers successfully isolated the toe from the loss zone. The client was then able to drill the 6-1/8” hole section, putting the depleted reservoir on a path to support the oil producer and ensuring the client could continue to derive value from it.