Abstract
Numerous operating companies are pursuing new and much deeper geologic horizons on the Gulf of Mexico continental shelf. This is a logical expansion of a geographic area with a very mature and well established surface infrastructure. However, as the well depths increase, the wellbore construction and well production operations become much more challenging because ultra-high pressures and high temperatures - HPHT (e.g. 25,000+psi and 450+°F) will then need to be handled and/or managed. The industry is probably able to safely drill these more extreme wells but there are some significant well completion technology gaps that require design and development. The most cost efficient approach to bridge these gaps may be for several companies to collaboratively share in the costs to develop the appropriate equipment for these applications.
This paper demonstrates the need to enhance the industry's capability to actually begin production from these deep ultra HPHT wellbores. The numerous areas that require increased completion capability will be presented in this paper. The production tubulars (casing and tubing) will be a major cost driver as designs will need to address temperature deration of strength, geometric complexity to achieve adequate bore and clearances, corrosion and environmental cracking. Risk analyses and testing will dictate metallurgy, pressure containment, connection capability under compression and bending, and benefits and reliability of cementing. Production packers, subsurface safety valves, and flow control nipples/plugs appear to be the nearest to implementation, but some design and qualification issues still need to be resolved. Current perforating technologies are reaching their limits at temperatures exceeding 450°F, thus require significant attention in their specific application and a quality assurance/quality control (QA/QC) program. The major hurtle for fully rated completion blowout preventors (BOP's) and trees will be the need to redesign the valve stem sealing mechanisms. Finally, both intervention and contingency possibilities, like slickline, pumping services, stimulation, snubbing, etc., are important situations that require additional enhancements to currently available technologies.
