Deepwater Completion Challenges Redefine Best Practices for Completion and Packer Fluid Selection

摘要

New materials used in deepwater production tubulars, and the increasingly complex and costly deepwater projects, demand greater attention to the design and selection of completion and packer fluids. This requires an integrated approach, from mud displacement through final sand control completion, in order to optimize fluid compatibility and effectiveness. In addition to standard compatibilities with reservoir rock and fluid, compatibilities of completion or packer fluid with control line, stimulation, and production fluids must be considered. Furthermore, compatibility of completion and packer fluids with production tubular metallurgies must be assured in order to prevent environmental cracking. The impact of the production environment on the potential formation of gas hydrates or crystallization of brine due to pressure, at the nearfreezing mudline temperatures, must be understood for each of the wellbore fluids used during the completion process. For some projects, more than one completion or packer fluid choice is available, in which case each fluid should be evaluated to select the best ‘fit-for-purpose’ fluid. This paper presents a new paradigm for testing and evaluating completion and packer fluids for selection in deepwater applications. Details for each test procedure and evaluation method are presented and include completion or packer fluid compatibilities with formation or synthetic formation water, control line fluids, and produced fluids. Core flow studies used to test fluid compatibility with the formation rock, and standard stress-cracking tests, conducted according to NACE guidelines, used to avoid the potential for environmentally assisted cracking of chrome production tubulars, are presented. Specialized evaluation methods to avoid the formation of gas hydrates and the pressure crystallization ofcompletion and packer fluids are also presented. The best fitfor- purpose fluid was selected by following this new paradigm for a GOM deepwater project. Lessons learned are summarized in the paper.