Expandable Tubulars Facilitate Improved Well Stimulation and Production
Authors: Bybee Karen 
Published: February 2015

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 121147, ’Expandable Tubulars Facilitate Improved Well Stimulation and Well Production,’ by Doug G. Durst, SPE, and Neven Ruzic, SPE, Enventure Global Technology, originally prepared for the 2009 SPE Western Regional Meeting, San Jose, California, 24-26 March.
Expandable technology applied as a completion/production string facilitates increased fracturing rates, resulting in improved conductivity and enhanced hydrocarbon production. Expandable tubulars can be used in re-entry wells to isolate old perforations, allowing new zones or new sections within zones to be perforated and stimulated. Either a combination tubular-cladding system or a solid expandable system can provide an integral component in new wells or re-entry wells where low-permeability reservoirs, such as those characteristic of unconventional gas formations, require isolation and separation for selective or pinpoint hydraulic fracturing or refracturing.
Introduction
One of the more notable technologies, solid expandable tubulars, has evolved to include systems that can be used in the following capacity:
In conventional applications for remediation, rejuvenation, and refurbishment of mature-field assets.
In unconventional gas completions in combination with hydra-jet (abrasive jetting) perforating and fracturing techniques.
As a large production conduit for deep and ultradeep wells in conventional wellbore-casing programs.
As a large production conduit to slim the wellbore and still attain adequate hole size at total depth.
Solid-expandable technology in production applications has been used extensively to address isolation challenges in cased-hole and openhole scenarios. Generally, an elastomeric compound is bonded to the outside diameter (OD) of the pipe to provide effective isolation. When the pipe is expanded to contact the wellbore inside diameter (ID), the elastomer is compressed between the formation and/or base casing and the expandable pipe, providing a hydraulic seal. Solid-expandable systems in production applications typically repair or reinforce existing casing and isolate sections such as perforated intervals and/or leaking connections. Anchor hangers (pup joints of expandable casing bonded with elastomers) are placed at the top and the bottom of the liner to isolate these intervals. Additional anchor hangers can be placed anywhere along the liner to address other requirements. By incorporating multiple anchor hangers, several zones can be isolated with one liner. The compound used for the elastomer bands on the anchor-hanger joints depends on downhole temperature and fluid compatibility. Elastomer bands of different thicknesses can be used on the same liner to seal in a variety of IDs or range of casing weights.
Solid-expandable technology plays a significant role in providing solutions in all types of production and completion applications. The general evolution of completion techniques has provided the means to carry out discrete multistage fracturing programs over long horizontal wellbores to create more connectivity. The newer solutions now provide better project economics by separating the drilling, casing, and completion aspects of the project from the fracturing operations, thereby gaining project efficiencies by not tying up the rig for all operations.