The Development and Applications of Solid Expandable Tubular Technology
Authors: Noel G. 
Published: March 2010

Operators face significant loss of inside diameter (ID) in the course of the normal drilling process, during re-entry and deepening of existing wells, or when installing additional casing strings to remediate well problems. The industry has confronted this dilemma with innovative problem solving that stretches the boundaries of physics in the guise of solid expandable tubular technology.

Successful applications have proven the technology's reliability in a variety of conditions and environments. Solid expandable tubulars continue to build a legacy as a solution to problems involving gas shut-off, subsidence repair, water shut-off, lost circulation, and remediation of wells slated for abandonment. The technology continues to evolve, leading to the single-diameter wellbore where casing diameter remains constant for the entire length of the well.

Introduction

hard and fast rule of casing design-that being each string of pipe must be able to pass through the previous string?has caused problems ranging from a simple inconvenience to premature abandonment and loss of reserves, or to the inability to complete an exploratory well.

Developers learned to reliably and repeatedly pass smaller diameter API standard size and grade pipe, and expand it such that its outside diameter (OD) is nearly equal to the ID of the previous casing string. This development was the impetus for solutions to many of the previously mentioned problems.

Solid expandable tubular technology provides feasible options for drilling, completion, and workover operations allowing operatorsto reach previously unattainable target zones. Solid expandable tubular installations have increased production, extended production life through remediation of existing pay zones, and provided the ability to reach target depths.

In a drilling application, solid expandable tubular technology reduces the telescopic effect created by using multiple casing strings in deepwater or extended reach wells, thereby preserving valuable hole size. Since its development, the technology has rapidly moved from deepwater to a technology that has been embraced by operators in many basins(1).

The Expansion Process

A launcher at the bottom of the solid expandable tubular system houses an expansion cone and a float shoe. The launcher is constructed of high-strength steel that consists of a thinner wall thickness than the expandable casing. The OD of the launcher can be up to the drift diameter of the previous casing or liner so it can still be tripped through the base casing. The thinner wall allows for the cone OD to be maximized.

The expandable system uses an elastomer joint to both seal and anchor the system. The elastomer joint incorporates multiple elastomer sections that are bonded to the pipe using a compression molding process. The rubberized elastomer materials are selected to meet the temperature requirements of the given installation. As the elastomer joint is expanded, the elastomer sections are energized and clad into the base casing. A designed compression ratio of the elastomer sections between the expanded pipe and the base casing gives the elastomer joints their sealing and loadbearing capabilities.