Technology Update: New Tool and Sealant Technology Expedites Annular Isolation Tasks
Authors: Gunnarsson Bengt , Tønnesen Sven Harald , Olsen Eugen , Leong Yuting 
Published: January 2017

Technology Update

Annular isolation issues are frequently discussed in well asset forums worldwide with a focus on improved oil recovery/ enhanced oil recovery applications or annular well integrity challenges. Conventional methods to repair annular isolation typically involve coiled tubing (CT) operations or heavy workovers, where it is necessary to pull the well tubing. These are high-cost procedures that are sometimes deferred.

We discuss herein the CannSeal technology, a well intervention tool that conveys and accurately places a proprietary epoxy sealant into an annulus at a predefined location in the well. The technology enables a level of precision in the placement of annular sealant that has not previously been possible. Considerable savings in rig time can be achieved, compared with alternative methods.

Operators can use the technology to isolate and improve the response to reservoir issues such as high water cuts and thief zones and efficiently repair and re-establish well barriers. As a result, well recompletions can be postponed or avoided.

The results of a field trial are included in this discussion.

The Technology

The technology was patented in 2005, following a joint industry project between Shell, Statoil, Eni, Total, and the Research Council of Norway. A field trial was performed in 2012 with Shell Appalachian in Pennsylvania (United States) with partial success, but revealed the need for further design improvements. ConocoPhillips, Maersk Oil, and BP contributed financially to support considerable reengineering and rigorous testing. Eventually, Maersk and BP spent resources on the final tool qualification processes to ensure that the equipment was ready for downhole operations. In late 2015, the tool was successfully run at Maersk’s Halfdan field in Denmark.

The technology concept consists of an electrical-wireline- or electrical-CT- (e-CT-) operated tool that incorporates the epoxy sealant. The sealant is premixed in the workshop and transferred to a steel container/canister within the tool assembly.

The tool incorporates an advanced telemetry communication system that provides the tool operator at the surface full control of

Position, using the integrated casing collar locator (CCL)

All tool functions

Perforation

Pumped sealant volume

Sealant injection rate and pressure

Tool and well pressures and temperatures

Emergency release features

When located at the precise target depth in the well, a three-hole perforation process is activated, which allows access to the entire circumference of the annulus. The sealant is injected and displaced exclusively into the annulus in a single operation without sealant spilling into the tubing (Fig. 1). The sealant will also seal the perforated holes without the subsequent need for patching. If the sealant is injected into a cement matrix for microannulus repair, a pumping differential pressure of 200 bar is achievable.

The proprietary sealant is designed with rheology properties that allow it to be injected into an open/cased-hole annulus with possible crossflow of water or into a gravel pack or cement matrix. The epoxy plug solidifies under well temperature conditions.