An Unconventional Cement Packer Repair

December 23, 2019

CannSeal delivery tool (Image: CannSeal)
CannSeal delivery tool (Image: CannSeal)

CannSeal unlocks development of an additional reservoir by restoring integrity to an unconventional cement packer design

Annular isolation technology specialist CannSeal aided the successful repair of an unconventional cement packer design, 4 ½” in 9 5/8” with limited cement. CannSeal’s technology achieved the objective of reducing the gas leak to within acceptable limits, thereby facilitating development of an additional reservoir.

In order to unlock additional accumulation, the wellbore was sealed off and the A-annulus was filled with cement above the top of the additional reservoir. Two long formation, or reservoir sections, were then perforated below the estimated Top of Cement (TOC) in the A-annulus. When production started, the A- and B-annuli developed gas influx issues. Conventional methods of sealing could not be used due to the risk of filling the reservoir with sealant through the perforated sections.

The cement below the estimated A-annulus TOC was of unknown quality and the 4 ½” tubing was placed inside the 9 5/8” casing. Perforating through a thick cement sheet, while not damaging the outer casing on the low side, was vital to the project. CannSeal’s criteria was to remove or reduce the gas leak to within acceptable limits.

The CannSeal IntegritySeal was run on wireline to perforate and inject epoxy in the cement above the top perforation interval. CannSeal’s high viscous sealant forms a doughnut around the tubing in an open void, or fills large channels in a poor cement matrix. This process creates a plug independent of annular condition.

Cannseal’s delivery tool is fitted with a g-sensor, which has the ability to show the tools relative orientation. As a result, eccentric centralizers were used to point the perforation gun in the desired direction. This allows selective penetration with max reach topside to occur, while not damaging the second casing in the eccentric annulus. The CannSeal heater tool was used in order to increase the epoxy materials cross linking, establishing a strong plug.

CannSeal tool ahead of installation (Photo: CannSeal)

A total of three epoxy injections was completed (31,6L ea.) throughout the job. The injections were placed in close proximity, and the CannSeal heater tool was deployed to increase the strength of the plug material. This enabled it to withstand high delta pressure in an anticipated large open void in the event there was no cement.  Orientation of the tool was successful despite a low clearance, making the concept viable for larger casings in the future.

The aim of lowering the gas leak rate was successfully achieved. A month after the treatment was completed the situation was reported to be similar, with the pressure build reduced to a minimum.

CannSeal’s Chief Executive Officer, Bengt Gunnarsson, said CannSeal is a problem solver for operators who experience unexpected well integrity issues. “Without a successful barrier repair, on this occasion it would not have been possible to develop this additional reservoir through conventional methods.

“Committed to innovation and global growth, we are proud to share success stories like this. Following the recent launch of our mobile mixer, we are now able to reach more markets faster than ever before.”

The launch of CannSeal’s new mobile mixer was a strategic investment for the company. Facilitating the company’s proprietary epoxy resin to be mixed on-site, the mobile mixer opens up new markets independent of location as it removes constrictions associated with storage and curing.

CannSeal’s high viscous epoxy resin (Photo: CannSeal)

This article has been published in the November/December 2019 edition of Offshore Engineer magazine

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