The introduction of expandable metal technology to the oil and gas industry in recent years has allowed a change in the traditional well construction design. The advent of this technology is allowing operators to drill wellbores that do not subscribe to the traditional telescoping reduction in casing sizes as well depth increases. In September 2006 the industry achieved a milestone in its quest to achieve an expandable monobore well. The milestone was the world's first true monobore expandable liner extension system. The successful installation of the expandable liner system was the end result of a collaborative development project between Baker Oil Tools and a major oil company that has been ongoing since spring 2004.
This paper will cover the background, development, and overview of the first commercial monobore expandable liner system.
At the turn of the millennium the exploration and production industry sought to prove the feasibility of monobore expandable liner extension systems as an advantageous alternative to conventional casing designs in order to address the technical needs of the increasingly challenging drilling environments.
The ability to drill wellbores that do not subscribe to the traditional telescoping reduction in casing sizes as the well depth increases will allow extended reach wells to be drilled without sacrificing casing size results in advantages over the traditional telescoping construction methods.
The goal of an expandable monobore liner extension is to enable the operator to drill deeper exploration and production wells with larger hole sizes at the reservoir. In addition expandable monobore wells provide the operator the ability to isolate zones that contain reactive shale's, sub-salt environments, low fracture gradient formation or other drilling situations without having to reduce the casing and subsequent enter into the production reservoir with reduced size production hole sections which may adversely affect well production.
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The use of expandable metal technology to construct a monobore well requires the selecting of the correct material and method of expansion to achieve desired expansion percentages and final performance properties. The performance properties are not only measured in empirical numbers such as burst/collapse/tensile rating but also in ability to provide a suitable solution to an application. Both of these factors must be developed and analyzed in unison in order for a system to perform as expected.
Material for use in expandable applications is evaluated and tested in regards to how it performs pre expansion, during the expansion process, and post expansion. The criteria used most commonly to classify and capture these material properties and performances in the three states are: toughness, work hardening, and the Bauschinger Effect.
