Continued Evolution of the One-Trip-Expansion, Single-Diameter Wellbore
Authors: Bybee Karen 
Published: February 2015

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 17437, "Continued Evolution of the One-Trip-Expansion, Single-Diameter Wellbore," by A. Filippov, SPE, and D. Zijsling, SPE, M. Akhideno, SPE, Shell, and K. Waddell, S. Costa, B. Watson, and B. Bell, Enventure Global Technology LLC, prepared for the 2005 SPE Offshore Technology Conference, Houston, 2–5 May. Copyright 2005 Offshore Technology Conference. Reproduced by permission.
With more than 300 commercial installations in place, solid-expandable-tubular technology has proved to be a viable and economically feasible alternative to conventional drilling technology. The need for lower lifting costs and to maximize recovery has provided the impetus for the latest step change toward the one-trip section, single-diameter wellbore. In addition to the unique equipment needed to expedite this game-changing technology, new implementations essential to realize the tool components and contingencies had to be developed and tested. The full-length paper explains the overall design and testing approach necessary for the construction of a single-diameter well.

Introduction
Installation of successive single-diameter expandable liners will revolutionize the way many wells are designed and executed. The potential cost savings of an ultraslim wellbore and maximized reservoir potential have been well documented. Single-diameter technology offers the following benefits.Significant increases in potential lateral reach.Significant increases in potential lateral and trouble time.Improvements in capital efficiency on drilled wells and overall field development.
This technology allows enhanced field-development flexibility and cost reductions in many worldwide field developments.
For example, increasing lateral reach and thus reservoir contact and drainage creates the potential for reduced well count and greater production per well. More production from fewer wells can lower the number of wells required and result in reduced drilling costs. Reduced trouble time and risk lowers drilling costs. This drilling optimization can result in lower facility and project capital requirements.

Field Applications
Use of single-diameter expandable-casing technology has the field-proven potential to reduce drilling and completion costs significantly. These savings are realized by reducing drilling risk and resultant trouble time by successively isolating problem lithology and/or underpressured zones while preserving a single-diameter wellbore. Gulf of Mexico (GOM) operators, who often encounter severe lost-circulation zones at shallow depths, are watching this technology development in hopes of expanding long drilling liners to isolate these underpressured zones and later case off the expanded liner and problem zones.
Successive installation of expandable, single-diameter wellbores can reduce the friction/drag forces that can limit lateral reach while preserving a single-diameter wellbore as deep as required. This application can provide higher weight on bit than conventional drilling technology at comparable depths.