Abstract
As the oil and gas industry has matured, three broad-reaching and long-standing issues that affect virtually every well have assumed heightened importance: conservation of hole size, hydraulic isolation of selected zones, and maximization of well life. All of these issues involve one of the industry’s most fundamental technologies, wellbore tubulars. Until recently, resolving these issues with conventional tubular technology was becoming ever more difficult, especially in deep-drilling and extended-reach applications, in wells utilizing liner hangers, and in aging wells containing deteriorating casing. A revolutionary new technology—expandable tubulars—has recently been introduced and has successfully addressed these issues in commercial applications.
The basic concept underlying expandable-tubular technology is simple: a mechanical expansion device, known as an expansion cone or mandrel, is propagated through downhole tubulars utilizing hydraulic pressure. The progress of the cone expands the tubulars to the desired internal and external diameters in a plastic deformation process known as cold drawing.
In drilling applications, a specially-designed liner hanger utilizing the new expandable-tubular technology conserves hole size by eliminating the need for a conventional liner hanger/liner hanger packer, and provides a superior pressure seal compared to the old technology. In cased wells, expandable casing is cladded to existing casing, either to repair or strengthen the existing casing, with minimal decrease in wellbore inside diameter (ID) and flow potential. Expandable tubular solutions have been successfully installed in the Gulf of Mexico, in U.S. inland wells, as well as in large-scale field trials.
This paper briefly describes the technical concepts upon which expandable tubulars are based and gives an overview of expandable-tubular applications. The paper then focuses on the most recent field installations, including systems installed during the first quarter of 2000. Discussions of field examples will contain customer objectives, job design, installation procedures, ultimate results and best practices learned.
