Helix Centraliser Enables Reliable Cement Evaluation Through Tight Restrictions

Exxon (Esso) Australia planned the permanent P&A of two offshore exploration wells, requiring verification of well barrier integrity behind the 9-5/8” casing in accordance with regulatory standards. To do this cost-effectively, an intervention semi- submersible was contracted, and SLB was engaged to deploy its advanced Epilogue technology—enabling simultaneous dual casing/annulus evaluation in a single run. However, the vessel’s 6-1/8” riser ID was too narrow for conventional fixed OD centralizers typically required for cement bond tools in the 8.535” ID of the 9-5/8” casing. To address the restriction, Petromac’s Helix CX9 slip-over centralizers were deployed on SLB’s IBC and CBL tools. The helical arms collapse to 5.625”, allowing smooth passage through the 6-1/8” riser, while still delivering over 200 lbs of centering force in 9-5/8” casing—even at 90° deviation—ensuring reliable centralization. A total of Six Epilogue runs were completed successfully across both wells, with smooth riser passage, optimal centralization, and high-quality data acquisition. Innovative centralizer overcomes ID constraints during offshore P&A operations Fig 1: Conventional centralisers are designed to centralize in only one casing size at a time. Helix passes through any restrictions seamlessly and centralizes in multiple casing sizes.