A client in the North Sea experienced critical losses when drilling the main bore for a series of horizontal wells prior to drilling the multilaterals. Prior wells used cement on the 9-5/8” casing or swell packers to stop the losses. Owing to the frequent failure of the cementing, there was a required 25-day waiting period to allow for the swells to achieve sealing. As a consequence, the laterals were not drilled, and production targets were not met.

Welltec® proposed setting the 812WAB to seal against the highly permeable rock face and divert the mud through the rock. The objective of this proposal was to use the mud with the lost circulation material to reduce the rock permeability while simultaneously building a mud cake.

The client agreed to the plan, and the WABs were mobilized to the site on short notice.

An 812WAB was deployed and hydraulically expanded below the 9-5/8” shoe within the main bore. Sealing was successful, effectively stopping the losses. Once this was achieved, the rig progressed with drilling the first of two multilaterals.

The first WAB successfully solved the issue in the main bore and allowed for the drilling of the laterals. A second WAB was used as a solution for the laterals themselves. A window was milled, and the first lateral was drilled into the depleted reservoir with no losses. An 812WAB was deployed to the first lateral to prevent losses while drilling the second lateral. The second window was then milled, and the second lateral was drilled with no losses.

Annular loss rate was successfully cured, indicating that the WAB packer was successfully sealing and providing annular isolation as planned.

This solution enabled the client to continue drilling the multilaterals without waiting on swell time. Drilling these two laterals led to the operator achieving oil production targets. Ultimately, Welltec’s solution solved a problem of critical loss in the main bore, accelerated the timetable to drill laterals, prevented losses during the drilling, and enabled the client to achieve production targets quickly and safely.
This operation was the first time a WAB has been used on laterals to isolate losses.