The sign of empowering technology may well lie in its adaptability, versatility, and reliability as it evolves from theoretical concept to practical application. Initially developed as a means to minimize the loss of hole size when setting successive casing strings, solid expandable tubulars are now considered revolutionary technology able to address a multitude of drilling conditions and challenges and adapt to a variety of applications.
In five years, expanding solid tubulars downhole has evolved from a promising idea to an operative means for well construction. Lessons learned have led not only to system improvements and a more efficient installation process but have also directly impacted the economics of drilling and production by affirming the versatility and reliability of the technology. Solid expandable tubulars boast an impressive range of application options; having been used as a contingency to mitigate drilling challenges as well as being used to provide an integral part of the wellbore design.
The first commercial installation of solid expandable tubulars was performed on a well in the shallow waters of the Gulf of Mexico in November 19991 (Figure 1). The objective of the installation was to reduce the well cost by using smaller casing sizes and drilling smaller hole sizes than would have been required when using a conventional casing program. Following this successful installation, and with increasing industry acceptance, the number of solid expandable tubular installations is now in excess of 300. More companies are entering the business of providing expandable tubulars to the industry and more operators are using expandables in their well programs.
Previous publications have discussed case histories and lessons learned during the early stages of solid expandable tubular technology development1, 2, 4. This paper will chronicle how lessons learned during the past five years have provided innovative ways of implementing solid expandable tubulars, enhanced the technology, streamlined the installation process, and attained a broader application window.
Expandable installations include openhole drilling liners for mitigation of drilling challenges such as control of lost circulation zones, casing shoe extensions, isolation of unstable formations. Cased-hole applications have been installed to isolate old perforated intervals or protect weak casing in areas where conventional squeeze cementing techniques were not expected to be effective in sealing off the open intervals. Open hole isolation of water bearing fractures has been successfully controlled by installing the solid expandable tubulars only across the problem area, rather than the entire open hole.
Initial installations of expandable tubulars were limited to relatively short liner lengths. During the first two years of expandable applications, the longest liner expanded was ?2,500 ft, with the average length of all liners installed at ?1,200 ft. In these early installations there was concern about the erosional effects of the metal-to-metal expansion and just how long the hardened steel expansion cone would retain its full expansion diameter. As expanded liner lengths increased, learnings revealed that the expansion cone could survive the process with little or no degradation.