Cementing for life
  from: Offshore Engineer
  by: Russell McCulley
  Thursday, October 02, 2008

Halliburton has bundled three proprietary zonal isolation technologies into a suite that the company says can help preserve cement integrity throughout the life of a well and prevent damage caused by sustained casing pressure (SCP). Marketed as WellLife III, the cementing service incorporates an analytical tool for design and delivery; automatically sealing cement technology; and the company’s Cement Assurance tool, a reactive gasket attached to the outside of casing sections that can swell to fill in incongruities, channels or micro-annuli.

According to Halliburton, the WellLife III service is ‘an interventionless react-and-respond solution designed to help address the industry-wide challenge of the loss of zonal isolation due to changes in the wellbore that can stress the cement sheath and lead to destabilization at any point during the life of the well’.

First element of the three-tier system is an analytical tool, WellLife Service, that the company has used around the world to determine cement properties for creation of a resilient sheath that can withstand future stresses, anticipated or otherwise. Should a sheath fail due to formation subsidence or tectonic movement, the WellLife III system adds a layer of protection with LifeCem or LifeSeal cement, which can react to such events and repair itself without surface intervention. The cements incorporate additives that activate swelling when flowing hydrocarbons are present. Halliburton says the additives have been used successfully in more than 70 wells throughout the world, both on- and offshore.

The final piece, the Cement Assurance tool, is designed to address the weakening over time of the bond between cement and the casing. Available in various degrees of thickness, the tool is used to coat one or more sections of casing before it is run into the well; once in place, wellbore conditions such as heat, wellbore fluids or flowing reservoir materials can be used to activate swelling of the element surrounding the casing.

The tool’s rubber compound can expand to twice its original size, but will remain dormant as long as the cement sheath retains its integrity and bond. Halliburton has used the tools in zonal isolation activities since 2005. OE

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