Rank wild cat deepwater exploration wells present an escalated set of challenges beyond even those encountered in the most complex offshore well construction. The presence of salt diapirs and well documented stressed pre- and post-salt formation layers produce greater distortion and unpredictability to geopressure and temperature gradients. It is customary to approach these challenges with casing design configurations that afford deployment of contingency casing strings without compromise to mechanical strength, well integrity and reaching the bottom-hole depth objective with the right casing bore size for production testing.
The use of expandable liners have become a panacea for extending hole sections — that may otherwise have truncated and narrowed the final depth — and terminating the hole size of deep reservoir targets respectively. Significant compromise in casing mechanical strength accompanies the application of expandable liners and their application must be carefully considered, alongside an array of qualified alternatives, especially above and across high pressured reservoir intervals.
The Expandable Hanger and Packer Liner (EHPL) System offers the preservation of the maximum bore size for subsequent hole and casing size, while allowing deployment in the tightest annuli that otherwise will have prevented the pass through and space for a conventional hanger deployment to achieve liner design and effective hang-off capacity. In the account presented in this paper, the technical evaluation process, deployment planning and challenges, and successful application industry-wide of the first liner with an expandable hanger and packer system is enumerated.