Centek is launching its Inter Casing Centraliser Sub (ICCS), designed to be run as part of a tight tolerance casing string in deepwater, ultra-narrow annulus applications.
Centek and Halliburton collaborated in developing the ICCS. The body of the centraliser sub is machined to Centek and Halliburton’s exacting standards. Centek’s patented UROS (Under Reamed Offset Bow) centraliser technology is installed on the sub body by Halliburton in a process that complies with the toughest quality control standards. The sub body, manufactured to API 5CT requirements, meets or exceeds all burst, collapse and tensile ratings. The UROS centraliser gives optimum restoring performance with minimal starting and running forces when passing through the tightest restrictions.
The centraliser is designed and manufactured with minimal clearance to the casing, and with a precisely formed cross bow curvature so that there are no “knife edges” (common among standard bow spring centralisers) which reduces the risk of subsea well head damage. Crucially, during operation the centraliser can recess completely into the sub body and so pass through the tightest of restrictions while protecting the bows from damage.
The centraliser’s single piece construction eliminates the risk of failure associated with welded bow to end band type designs, and this coupled with precise manufacturing enables the centralizer sub to rotate within the centraliser at minimal torque values. The unique interlocked band design means that the strength of the centraliser end-bands does not depend on quality or installer skill, but is as strong as the single piece of steel used in Centek’s centralisers. In addition, the weld pocket recesses are designed to ensure there is no need for a pronounced weld bead with the risk of friction grinding the bead down and weakening the weld.
“Centek appreciates the need for a close tolerance centraliser for use in very tight annulus applications, where the margins between pore pressure and the fracture gradient are narrow,” said Cliff Berry, vice-president, Global Business Development at Centek Group. “Not only can the UROS centraliser fully compress within the sub body, but the Centek sub has the ability to rotate when fully compressed in the tightest of restrictions with no loss of eccentricity at the end-bands.” The size range is expected to be 7.3/4 -inch through to 180-inch or as required, and the sub body can be threaded to meet the customer’s requirements for the casing string.
